[project @ 2000-04-04 15:02:02 by simonmar]
[ghc-hetmet.git] / ghc / rts / Schedule.c
index 1a96f87..1f1faa1 100644 (file)
@@ -1,11 +1,18 @@
-/* -----------------------------------------------------------------------------
- * $Id: Schedule.c,v 1.40 2000/01/13 10:37:31 simonmar Exp $
+/* ---------------------------------------------------------------------------
+ * $Id: Schedule.c,v 1.63 2000/04/04 15:02:02 simonmar Exp $
  *
- * (c) The GHC Team, 1998-1999
+ * (c) The GHC Team, 1998-2000
  *
  * Scheduler
  *
- * ---------------------------------------------------------------------------*/
+ * The main scheduling code in GranSim is quite different from that in std
+ * (concurrent) Haskell: while concurrent Haskell just iterates over the
+ * threads in the runnable queue, GranSim is event driven, i.e. it iterates
+ * over the events in the global event queue.  -- HWL
+ * --------------------------------------------------------------------------*/
+
+//@node Main scheduling code, , ,
+//@section Main scheduling code
 
 /* Version with scheduler monitor support for SMPs.
 
    SDM & KH, 10/99
 */
 
+//@menu
+//* Includes::                 
+//* Variables and Data structures::  
+//* Main scheduling loop::     
+//* Suspend and Resume::       
+//* Run queue code::           
+//* Garbage Collextion Routines::  
+//* Blocking Queue Routines::  
+//* Exception Handling Routines::  
+//* Debugging Routines::       
+//* Index::                    
+//@end menu
+
+//@node Includes, Variables and Data structures, Main scheduling code, Main scheduling code
+//@subsection Includes
+
 #include "Rts.h"
 #include "SchedAPI.h"
 #include "RtsUtils.h"
 #include "Printer.h"
 #include "Main.h"
 #include "Signals.h"
-#include "Profiling.h"
 #include "Sanity.h"
 #include "Stats.h"
+#include "Itimer.h"
+#include "Prelude.h"
+#if defined(GRAN) || defined(PAR)
+# include "GranSimRts.h"
+# include "GranSim.h"
+# include "ParallelRts.h"
+# include "Parallel.h"
+# include "ParallelDebug.h"
+# include "FetchMe.h"
+# include "HLC.h"
+#endif
 #include "Sparks.h"
 
 #include <stdarg.h>
 
+//@node Variables and Data structures, Prototypes, Includes, Main scheduling code
+//@subsection Variables and Data structures
+
 /* Main threads:
  *
  * These are the threads which clients have requested that we run.  
  *
  * Main threads information is kept in a linked list:
  */
+//@cindex StgMainThread
 typedef struct StgMainThread_ {
   StgTSO *         tso;
   SchedulerStatus  stat;
@@ -83,11 +120,39 @@ static StgMainThread *main_threads;
 /* Thread queues.
  * Locks required: sched_mutex.
  */
+#if defined(GRAN)
+
+StgTSO* ActiveTSO = NULL; /* for assigning system costs; GranSim-Light only */
+/* rtsTime TimeOfNextEvent, EndOfTimeSlice;            now in GranSim.c */
+
+/* 
+   In GranSim we have a runable and a blocked queue for each processor.
+   In order to minimise code changes new arrays run_queue_hds/tls
+   are created. run_queue_hd is then a short cut (macro) for
+   run_queue_hds[CurrentProc] (see GranSim.h).
+   -- HWL
+*/
+StgTSO *run_queue_hds[MAX_PROC], *run_queue_tls[MAX_PROC];
+StgTSO *blocked_queue_hds[MAX_PROC], *blocked_queue_tls[MAX_PROC];
+StgTSO *ccalling_threadss[MAX_PROC];
+/* We use the same global list of threads (all_threads) in GranSim as in
+   the std RTS (i.e. we are cheating). However, we don't use this list in
+   the GranSim specific code at the moment (so we are only potentially
+   cheating).  */
+
+#else /* !GRAN */
+
 StgTSO *run_queue_hd, *run_queue_tl;
 StgTSO *blocked_queue_hd, *blocked_queue_tl;
 
+#endif
+
+/* Linked list of all threads.
+ * Used for detecting garbage collected threads.
+ */
+StgTSO *all_threads;
+
 /* Threads suspended in _ccall_GC.
- * Locks required: sched_mutex.
  */
 static StgTSO *suspended_ccalling_threads;
 
@@ -100,14 +165,17 @@ static StgTSO *threadStackOverflow(StgTSO *tso);
 */
 
 /* flag set by signal handler to precipitate a context switch */
+//@cindex context_switch
 nat context_switch;
 
 /* if this flag is set as well, give up execution */
+//@cindex interrupted
 rtsBool interrupted;
 
 /* Next thread ID to allocate.
  * Locks required: sched_mutex
  */
+//@cindex next_thread_id
 StgThreadID next_thread_id = 1;
 
 /*
@@ -132,10 +200,17 @@ StgThreadID next_thread_id = 1;
  * Locks required: sched_mutex.
  */
 #ifdef SMP
-Capability *free_capabilities; /* Available capabilities for running threads */
-nat n_free_capabilities;        /* total number of available capabilities */
+//@cindex free_capabilities
+//@cindex n_free_capabilities
+Capability *free_capabilities; /* Available capabilities for running threads */
+nat n_free_capabilities;       /* total number of available capabilities */
 #else
-Capability MainRegTable;       /* for non-SMP, we have one global capability */
+//@cindex MainRegTable
+Capability MainRegTable;       /* for non-SMP, we have one global capability */
+#endif
+
+#if defined(GRAN)
+StgTSO *CurrentTSO;
 #endif
 
 rtsBool ready_to_gc;
@@ -143,6 +218,7 @@ rtsBool ready_to_gc;
 /* All our current task ids, saved in case we need to kill them later.
  */
 #ifdef SMP
+//@cindex task_ids
 task_info *task_ids;
 #endif
 
@@ -150,13 +226,21 @@ void            addToBlockedQueue ( StgTSO *tso );
 
 static void     schedule          ( void );
        void     interruptStgRts   ( void );
+#if defined(GRAN)
+static StgTSO * createThread_     ( nat size, rtsBool have_lock, StgInt pri );
+#else
 static StgTSO * createThread_     ( nat size, rtsBool have_lock );
+#endif
 
 #ifdef DEBUG
 static void sched_belch(char *s, ...);
 #endif
 
 #ifdef SMP
+//@cindex sched_mutex
+//@cindex term_mutex
+//@cindex thread_ready_cond
+//@cindex gc_pending_cond
 pthread_mutex_t sched_mutex       = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutex_t term_mutex        = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t  thread_ready_cond = PTHREAD_COND_INITIALIZER;
@@ -165,7 +249,39 @@ pthread_cond_t  gc_pending_cond   = PTHREAD_COND_INITIALIZER;
 nat await_death;
 #endif
 
-/* -----------------------------------------------------------------------------
+#if defined(PAR)
+StgTSO *LastTSO;
+rtsTime TimeOfLastYield;
+#endif
+
+#if DEBUG
+char *whatNext_strs[] = {
+  "ThreadEnterGHC",
+  "ThreadRunGHC",
+  "ThreadEnterHugs",
+  "ThreadKilled",
+  "ThreadComplete"
+};
+
+char *threadReturnCode_strs[] = {
+  "HeapOverflow",                      /* might also be StackOverflow */
+  "StackOverflow",
+  "ThreadYielding",
+  "ThreadBlocked",
+  "ThreadFinished"
+};
+#endif
+
+/*
+ * The thread state for the main thread.
+// ToDo: check whether not needed any more
+StgTSO   *MainTSO;
+ */
+
+//@node Main scheduling loop, Suspend and Resume, Prototypes, Main scheduling code
+//@subsection Main scheduling loop
+
+/* ---------------------------------------------------------------------------
    Main scheduling loop.
 
    We use round-robin scheduling, each thread returning to the
@@ -184,19 +300,77 @@ nat await_death;
       * waiting for work, or
       * waiting for a GC to complete.
 
-   -------------------------------------------------------------------------- */
-
+   GRAN version:
+     In a GranSim setup this loop iterates over the global event queue.
+     This revolves around the global event queue, which determines what 
+     to do next. Therefore, it's more complicated than either the 
+     concurrent or the parallel (GUM) setup.
+
+   GUM version:
+     GUM iterates over incoming messages.
+     It starts with nothing to do (thus CurrentTSO == END_TSO_QUEUE),
+     and sends out a fish whenever it has nothing to do; in-between
+     doing the actual reductions (shared code below) it processes the
+     incoming messages and deals with delayed operations 
+     (see PendingFetches).
+     This is not the ugliest code you could imagine, but it's bloody close.
+
+   ------------------------------------------------------------------------ */
+//@cindex schedule
 static void
 schedule( void )
 {
   StgTSO *t;
   Capability *cap;
   StgThreadReturnCode ret;
+#if defined(GRAN)
+  rtsEvent *event;
+#elif defined(PAR)
+  StgSparkPool *pool;
+  rtsSpark spark;
+  StgTSO *tso;
+  GlobalTaskId pe;
+#endif
+  rtsBool was_interrupted = rtsFalse;
   
   ACQUIRE_LOCK(&sched_mutex);
 
+#if defined(GRAN)
+
+  /* set up first event to get things going */
+  /* ToDo: assign costs for system setup and init MainTSO ! */
+  new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc],
+           ContinueThread, 
+           CurrentTSO, (StgClosure*)NULL, (rtsSpark*)NULL);
+
+  IF_DEBUG(gran,
+          fprintf(stderr, "GRAN: Init CurrentTSO (in schedule) = %p\n", CurrentTSO);
+          G_TSO(CurrentTSO, 5));
+
+  if (RtsFlags.GranFlags.Light) {
+    /* Save current time; GranSim Light only */
+    CurrentTSO->gran.clock = CurrentTime[CurrentProc];
+  }      
+
+  event = get_next_event();
+
+  while (event!=(rtsEvent*)NULL) {
+    /* Choose the processor with the next event */
+    CurrentProc = event->proc;
+    CurrentTSO = event->tso;
+
+#elif defined(PAR)
+
+  while (!GlobalStopPending) {          /* GlobalStopPending set in par_exit */
+
+#else
+
   while (1) {
 
+#endif
+
+    IF_DEBUG(scheduler, printAllThreads());
+
     /* If we're interrupted (the user pressed ^C, or some other
      * termination condition occurred), kill all the currently running
      * threads.
@@ -211,6 +385,8 @@ schedule( void )
       }
       run_queue_hd = run_queue_tl = END_TSO_QUEUE;
       blocked_queue_hd = blocked_queue_tl = END_TSO_QUEUE;
+      interrupted = rtsFalse;
+      was_interrupted = rtsTrue;
     }
 
     /* Go through the list of main threads and wake up any
@@ -223,7 +399,7 @@ schedule( void )
       StgMainThread *m, **prev;
       prev = &main_threads;
       for (m = main_threads; m != NULL; m = m->link) {
-       switch (m->tso->whatNext) {
+       switch (m->tso->what_next) {
        case ThreadComplete:
          if (m->ret) {
            *(m->ret) = (StgClosure *)m->tso->sp[0];
@@ -234,7 +410,11 @@ schedule( void )
          break;
        case ThreadKilled:
          *prev = m->link;
-         m->stat = Killed;
+         if (was_interrupted) {
+           m->stat = Interrupted;
+         } else {
+           m->stat = Killed;
+         }
          pthread_cond_broadcast(&m->wakeup);
          break;
        default:
@@ -242,21 +422,30 @@ schedule( void )
        }
       }
     }
+
 #else
+# if defined(PAR)
+    /* in GUM do this only on the Main PE */
+    if (IAmMainThread)
+# endif
     /* If our main thread has finished or been killed, return.
      */
     {
       StgMainThread *m = main_threads;
-      if (m->tso->whatNext == ThreadComplete
-         || m->tso->whatNext == ThreadKilled) {
+      if (m->tso->what_next == ThreadComplete
+         || m->tso->what_next == ThreadKilled) {
        main_threads = main_threads->link;
-       if (m->tso->whatNext == ThreadComplete) {
+       if (m->tso->what_next == ThreadComplete) {
          /* we finished successfully, fill in the return value */
          if (m->ret) { *(m->ret) = (StgClosure *)m->tso->sp[0]; };
          m->stat = Success;
          return;
        } else {
-         m->stat = Killed;
+         if (was_interrupted) {
+           m->stat = Interrupted;
+         } else {
+           m->stat = Killed;
+         }
          return;
        }
       }
@@ -267,7 +456,7 @@ schedule( void )
      * number of threads in the run queue equal to the number of
      * free capabilities.
      */
-#if defined(SMP) || defined(PAR)
+#if defined(SMP)
     {
       nat n = n_free_capabilities;
       StgTSO *tso = run_queue_hd;
@@ -284,11 +473,14 @@ schedule( void )
        if (spark == NULL) {
          break; /* no more sparks in the pool */
        } else {
+         /* I'd prefer this to be done in activateSpark -- HWL */
+         /* tricky - it needs to hold the scheduler lock and
+          * not try to re-acquire it -- SDM */
          StgTSO *tso;
          tso = createThread_(RtsFlags.GcFlags.initialStkSize, rtsTrue);
          pushClosure(tso,spark);
          PUSH_ON_RUN_QUEUE(tso);
-#ifdef ToDo
+#ifdef PAR
          advisory_thread_count++;
 #endif
          
@@ -304,7 +496,7 @@ schedule( void )
          pthread_cond_signal(&thread_ready_cond);
       }
     }
-#endif /* SMP || PAR */
+#endif /* SMP */
 
     /* Check whether any waiting threads need to be woken up.  If the
      * run queue is empty, and there are no other tasks running, we
@@ -347,6 +539,10 @@ schedule( void )
       main_threads = NULL;
     }
 #else /* ! SMP */
+    /* 
+       In GUM all non-main PEs come in here with no work;
+       we ignore multiple main threads for now 
+
     if (blocked_queue_hd == END_TSO_QUEUE
        && run_queue_hd == END_TSO_QUEUE) {
       StgMainThread *m = main_threads;
@@ -355,6 +551,7 @@ schedule( void )
       main_threads = m->link;
       return;
     }
+    */
 #endif
 
 #ifdef SMP
@@ -375,10 +572,258 @@ schedule( void )
       IF_DEBUG(scheduler, sched_belch("work now available"));
     }
 #endif
+
+#if defined(GRAN)
+
+    if (RtsFlags.GranFlags.Light)
+      GranSimLight_enter_system(event, &ActiveTSO); // adjust ActiveTSO etc
+
+    /* adjust time based on time-stamp */
+    if (event->time > CurrentTime[CurrentProc] &&
+        event->evttype != ContinueThread)
+      CurrentTime[CurrentProc] = event->time;
+    
+    /* Deal with the idle PEs (may issue FindWork or MoveSpark events) */
+    if (!RtsFlags.GranFlags.Light)
+      handleIdlePEs();
+
+    IF_DEBUG(gran, fprintf(stderr, "GRAN: switch by event-type\n"))
+
+    /* main event dispatcher in GranSim */
+    switch (event->evttype) {
+      /* Should just be continuing execution */
+    case ContinueThread:
+      IF_DEBUG(gran, fprintf(stderr, "GRAN: doing ContinueThread\n"));
+      /* ToDo: check assertion
+      ASSERT(run_queue_hd != (StgTSO*)NULL &&
+            run_queue_hd != END_TSO_QUEUE);
+      */
+      /* Ignore ContinueThreads for fetching threads (if synchr comm) */
+      if (!RtsFlags.GranFlags.DoAsyncFetch &&
+         procStatus[CurrentProc]==Fetching) {
+       belch("ghuH: Spurious ContinueThread while Fetching ignored; TSO %d (%p) [PE %d]",
+             CurrentTSO->id, CurrentTSO, CurrentProc);
+       goto next_thread;
+      }        
+      /* Ignore ContinueThreads for completed threads */
+      if (CurrentTSO->what_next == ThreadComplete) {
+       belch("ghuH: found a ContinueThread event for completed thread %d (%p) [PE %d] (ignoring ContinueThread)", 
+             CurrentTSO->id, CurrentTSO, CurrentProc);
+       goto next_thread;
+      }        
+      /* Ignore ContinueThreads for threads that are being migrated */
+      if (PROCS(CurrentTSO)==Nowhere) { 
+       belch("ghuH: trying to run the migrating TSO %d (%p) [PE %d] (ignoring ContinueThread)",
+             CurrentTSO->id, CurrentTSO, CurrentProc);
+       goto next_thread;
+      }
+      /* The thread should be at the beginning of the run queue */
+      if (CurrentTSO!=run_queue_hds[CurrentProc]) { 
+       belch("ghuH: TSO %d (%p) [PE %d] is not at the start of the run_queue when doing a ContinueThread",
+             CurrentTSO->id, CurrentTSO, CurrentProc);
+       break; // run the thread anyway
+      }
+      /*
+      new_event(proc, proc, CurrentTime[proc],
+               FindWork,
+               (StgTSO*)NULL, (StgClosure*)NULL, (rtsSpark*)NULL);
+      goto next_thread; 
+      */ /* Catches superfluous CONTINUEs -- should be unnecessary */
+      break; // now actually run the thread; DaH Qu'vam yImuHbej 
+
+    case FetchNode:
+      do_the_fetchnode(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case GlobalBlock:
+      do_the_globalblock(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case FetchReply:
+      do_the_fetchreply(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case UnblockThread:   /* Move from the blocked queue to the tail of */
+      do_the_unblock(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case ResumeThread:  /* Move from the blocked queue to the tail of */
+      /* the runnable queue ( i.e. Qu' SImqa'lu') */ 
+      event->tso->gran.blocktime += 
+       CurrentTime[CurrentProc] - event->tso->gran.blockedat;
+      do_the_startthread(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case StartThread:
+      do_the_startthread(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case MoveThread:
+      do_the_movethread(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case MoveSpark:
+      do_the_movespark(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    case FindWork:
+      do_the_findwork(event);
+      goto next_thread;             /* handle next event in event queue  */
+      
+    default:
+      barf("Illegal event type %u\n", event->evttype);
+    }  /* switch */
+    
+    /* This point was scheduler_loop in the old RTS */
+
+    IF_DEBUG(gran, belch("GRAN: after main switch"));
+
+    TimeOfLastEvent = CurrentTime[CurrentProc];
+    TimeOfNextEvent = get_time_of_next_event();
+    IgnoreEvents=(TimeOfNextEvent==0); // HWL HACK
+    // CurrentTSO = ThreadQueueHd;
+
+    IF_DEBUG(gran, belch("GRAN: time of next event is: %ld", 
+                        TimeOfNextEvent));
+
+    if (RtsFlags.GranFlags.Light) 
+      GranSimLight_leave_system(event, &ActiveTSO); 
+
+    EndOfTimeSlice = CurrentTime[CurrentProc]+RtsFlags.GranFlags.time_slice;
+
+    IF_DEBUG(gran, 
+            belch("GRAN: end of time-slice is %#lx", EndOfTimeSlice));
+
+    /* in a GranSim setup the TSO stays on the run queue */
+    t = CurrentTSO;
+    /* Take a thread from the run queue. */
+    t = POP_RUN_QUEUE(); // take_off_run_queue(t);
+
+    IF_DEBUG(gran, 
+            fprintf(stderr, "GRAN: About to run current thread, which is\n");
+            G_TSO(t,5))
+
+    context_switch = 0; // turned on via GranYield, checking events and time slice
+
+    IF_DEBUG(gran, 
+            DumpGranEvent(GR_SCHEDULE, t));
+
+    procStatus[CurrentProc] = Busy;
+
+#elif defined(PAR)
+
+    if (PendingFetches != END_BF_QUEUE) {
+        processFetches();
+    }
+
+    /* ToDo: phps merge with spark activation above */
+    /* check whether we have local work and send requests if we have none */
+    if (run_queue_hd == END_TSO_QUEUE) {  /* no runnable threads */
+      /* :-[  no local threads => look out for local sparks */
+      /* the spark pool for the current PE */
+      pool = &(MainRegTable.rSparks); // generalise to cap = &MainRegTable
+      if (advisory_thread_count < RtsFlags.ParFlags.maxThreads &&
+         pool->hd < pool->tl) {
+       /* 
+        * ToDo: add GC code check that we really have enough heap afterwards!!
+        * Old comment:
+        * If we're here (no runnable threads) and we have pending
+        * sparks, we must have a space problem.  Get enough space
+        * to turn one of those pending sparks into a
+        * thread... 
+        */
+       
+       spark = findSpark();                /* get a spark */
+       if (spark != (rtsSpark) NULL) {
+         tso = activateSpark(spark);       /* turn the spark into a thread */
+         IF_PAR_DEBUG(schedule,
+                      belch("==== schedule: Created TSO %d (%p); %d threads active",
+                            tso->id, tso, advisory_thread_count));
+
+         if (tso==END_TSO_QUEUE) { /* failed to activate spark->back to loop */
+           belch("==^^ failed to activate spark");
+           goto next_thread;
+         }               /* otherwise fall through & pick-up new tso */
+       } else {
+         IF_PAR_DEBUG(verbose,
+                      belch("==^^ no local sparks (spark pool contains only NFs: %d)", 
+                            spark_queue_len(pool)));
+         goto next_thread;
+       }
+      } else  
+      /* =8-[  no local sparks => look for work on other PEs */
+      {
+       /*
+        * We really have absolutely no work.  Send out a fish
+        * (there may be some out there already), and wait for
+        * something to arrive.  We clearly can't run any threads
+        * until a SCHEDULE or RESUME arrives, and so that's what
+        * we're hoping to see.  (Of course, we still have to
+        * respond to other types of messages.)
+        */
+       if (//!fishing &&  
+           outstandingFishes < RtsFlags.ParFlags.maxFishes ) { // &&
+         // (last_fish_arrived_at+FISH_DELAY < CURRENT_TIME)) {
+         /* fishing set in sendFish, processFish;
+            avoid flooding system with fishes via delay */
+         pe = choosePE();
+         sendFish(pe, mytid, NEW_FISH_AGE, NEW_FISH_HISTORY, 
+                  NEW_FISH_HUNGER);
+       }
+       
+       processMessages();
+       goto next_thread;
+       // ReSchedule(0);
+      }
+    } else if (PacketsWaiting()) {  /* Look for incoming messages */
+      processMessages();
+    }
+
+    /* Now we are sure that we have some work available */
+    ASSERT(run_queue_hd != END_TSO_QUEUE);
+    /* Take a thread from the run queue, if we have work */
+    t = POP_RUN_QUEUE();  // take_off_run_queue(END_TSO_QUEUE);
+
+    /* ToDo: write something to the log-file
+    if (RTSflags.ParFlags.granSimStats && !sameThread)
+        DumpGranEvent(GR_SCHEDULE, RunnableThreadsHd);
+
+    CurrentTSO = t;
+    */
+    /* the spark pool for the current PE */
+    pool = &(MainRegTable.rSparks); // generalise to cap = &MainRegTable
+
+    IF_DEBUG(scheduler, belch("--^^ %d sparks on [%#x] (hd=%x; tl=%x; base=%x, lim=%x)", 
+                             spark_queue_len(pool), 
+                             CURRENT_PROC,
+                             pool->hd, pool->tl, pool->base, pool->lim));
+
+    IF_DEBUG(scheduler, belch("--== %d threads on [%#x] (hd=%x; tl=%x)", 
+                             run_queue_len(), CURRENT_PROC,
+                             run_queue_hd, run_queue_tl));
+
+#if 0
+    if (t != LastTSO) {
+      /* 
+        we are running a different TSO, so write a schedule event to log file
+        NB: If we use fair scheduling we also have to write  a deschedule 
+            event for LastTSO; with unfair scheduling we know that the
+            previous tso has blocked whenever we switch to another tso, so
+            we don't need it in GUM for now
+      */
+      DumpRawGranEvent(CURRENT_PROC, CURRENT_PROC,
+                      GR_SCHEDULE, t, (StgClosure *)NULL, 0, 0);
+      
+    }
+#endif
+#else /* !GRAN && !PAR */
   
     /* grab a thread from the run queue
      */
     t = POP_RUN_QUEUE();
+    IF_DEBUG(sanity,checkTSO(t));
+
+#endif
     
     /* grab a capability
      */
@@ -400,12 +845,18 @@ schedule( void )
       context_switch = 1;
 
     RELEASE_LOCK(&sched_mutex);
-    
+
+#if defined(GRAN) || defined(PAR)    
+    IF_DEBUG(scheduler, belch("-->> Running TSO %ld (%p) %s ...", 
+                             t->id, t, whatNext_strs[t->what_next]));
+#else
     IF_DEBUG(scheduler,sched_belch("running thread %d", t->id));
+#endif
 
+    /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
     /* Run the current thread 
      */
-    switch (cap->rCurrentTSO->whatNext) {
+    switch (cap->rCurrentTSO->what_next) {
     case ThreadKilled:
     case ThreadComplete:
       /* Thread already finished, return to scheduler. */
@@ -431,8 +882,9 @@ schedule( void )
       barf("Panic: entered a BCO but no bytecode interpreter in this build");
 #endif
     default:
-      barf("schedule: invalid whatNext field");
+      barf("schedule: invalid what_next field");
     }
+    /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
     
     /* Costs for the scheduler are assigned to CCS_SYSTEM */
 #ifdef PROFILING
@@ -443,30 +895,44 @@ schedule( void )
 
 #ifdef SMP
     IF_DEBUG(scheduler,fprintf(stderr,"scheduler (task %ld): ", pthread_self()););
-#else
+#elif !defined(GRAN) && !defined(PAR)
     IF_DEBUG(scheduler,fprintf(stderr,"scheduler: "););
 #endif
     t = cap->rCurrentTSO;
     
+#if defined(PAR)
+    /* HACK 675: if the last thread didn't yield, make sure to print a 
+       SCHEDULE event to the log file when StgRunning the next thread, even
+       if it is the same one as before */
+    LastTSO = t; //(ret == ThreadBlocked) ? END_TSO_QUEUE : t; 
+    TimeOfLastYield = CURRENT_TIME;
+#endif
+
     switch (ret) {
     case HeapOverflow:
       /* make all the running tasks block on a condition variable,
        * maybe set context_switch and wait till they all pile in,
        * then have them wait on a GC condition variable.
        */
-      IF_DEBUG(scheduler,belch("thread %ld stopped: HeapOverflow", t->id));
+      IF_DEBUG(scheduler,belch("--<< thread %ld (%p; %s) stopped: HeapOverflow", 
+                              t->id, t, whatNext_strs[t->what_next]));
       threadPaused(t);
+#if defined(GRAN)
+      ASSERT(!is_on_queue(t,CurrentProc));
+#endif
       
       ready_to_gc = rtsTrue;
       context_switch = 1;              /* stop other threads ASAP */
       PUSH_ON_RUN_QUEUE(t);
+      /* actual GC is done at the end of the while loop */
       break;
       
     case StackOverflow:
+      IF_DEBUG(scheduler,belch("--<< thread %ld (%p; %s) stopped, StackOverflow", 
+                              t->id, t, whatNext_strs[t->what_next]));
       /* just adjust the stack for this thread, then pop it back
        * on the run queue.
        */
-      IF_DEBUG(scheduler,belch("thread %ld stopped, StackOverflow", t->id));
       threadPaused(t);
       { 
        StgMainThread *m;
@@ -475,47 +941,118 @@ schedule( void )
        
        /* This TSO has moved, so update any pointers to it from the
         * main thread stack.  It better not be on any other queues...
-        * (it shouldn't be)
+        * (it shouldn't be).
         */
        for (m = main_threads; m != NULL; m = m->link) {
          if (m->tso == t) {
            m->tso = new_t;
          }
        }
+       threadPaused(new_t);
        PUSH_ON_RUN_QUEUE(new_t);
       }
       break;
 
     case ThreadYielding:
+#if defined(GRAN)
+      IF_DEBUG(gran, 
+              DumpGranEvent(GR_DESCHEDULE, t));
+      globalGranStats.tot_yields++;
+#elif defined(PAR)
+      IF_DEBUG(par, 
+              DumpGranEvent(GR_DESCHEDULE, t));
+#endif
       /* put the thread back on the run queue.  Then, if we're ready to
        * GC, check whether this is the last task to stop.  If so, wake
        * up the GC thread.  getThread will block during a GC until the
        * GC is finished.
        */
       IF_DEBUG(scheduler,
-              if (t->whatNext == ThreadEnterHugs) {
-                /* ToDo: or maybe a timer expired when we were in Hugs?
-                 * or maybe someone hit ctrl-C
-                 */
-                belch("thread %ld stopped to switch to Hugs", t->id);
-              } else {
-                belch("thread %ld stopped, yielding", t->id);
-              }
-              );
+               if (t->what_next == ThreadEnterHugs) {
+                  /* ToDo: or maybe a timer expired when we were in Hugs?
+                   * or maybe someone hit ctrl-C
+                    */
+                   belch("--<< thread %ld (%p; %s) stopped to switch to Hugs", 
+                        t->id, t, whatNext_strs[t->what_next]);
+               } else {
+                   belch("--<< thread %ld (%p; %s) stopped, yielding", 
+                        t->id, t, whatNext_strs[t->what_next]);
+               }
+               );
       threadPaused(t);
+      IF_DEBUG(sanity,
+              //belch("&& Doing sanity check on yielding TSO %ld.", t->id);
+              checkTSO(t));
+      ASSERT(t->link == END_TSO_QUEUE);
+#if defined(GRAN)
+      ASSERT(!is_on_queue(t,CurrentProc));
+
+      IF_DEBUG(sanity,
+              //belch("&& Doing sanity check on all ThreadQueues (and their TSOs).");
+              checkThreadQsSanity(rtsTrue));
+#endif
       APPEND_TO_RUN_QUEUE(t);
+#if defined(GRAN)
+      /* add a ContinueThread event to actually process the thread */
+      new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc],
+               ContinueThread,
+               t, (StgClosure*)NULL, (rtsSpark*)NULL);
+      IF_GRAN_DEBUG(bq, 
+              belch("GRAN: eventq and runnableq after adding yielded thread to queue again:");
+              G_EVENTQ(0);
+              G_CURR_THREADQ(0))
+#endif /* GRAN */
       break;
       
     case ThreadBlocked:
+#if defined(GRAN)
+      IF_DEBUG(scheduler,
+              belch("--<< thread %ld (%p; %s) stopped, blocking on node %p [PE %d] with BQ: ", 
+                              t->id, t, whatNext_strs[t->what_next], t->block_info.closure, (t->block_info.closure==(StgClosure*)NULL ? 99 : where_is(t->block_info.closure)));
+              if (t->block_info.closure!=(StgClosure*)NULL) print_bq(t->block_info.closure));
+
+      // ??? needed; should emit block before
+      IF_DEBUG(gran, 
+              DumpGranEvent(GR_DESCHEDULE, t)); 
+      prune_eventq(t, (StgClosure *)NULL); // prune ContinueThreads for t
+      /*
+       ngoq Dogh!
+      ASSERT(procStatus[CurrentProc]==Busy || 
+             ((procStatus[CurrentProc]==Fetching) && 
+             (t->block_info.closure!=(StgClosure*)NULL)));
+      if (run_queue_hds[CurrentProc] == END_TSO_QUEUE &&
+         !(!RtsFlags.GranFlags.DoAsyncFetch &&
+           procStatus[CurrentProc]==Fetching)) 
+       procStatus[CurrentProc] = Idle;
+      */
+#elif defined(PAR)
+      IF_DEBUG(par, 
+              DumpGranEvent(GR_DESCHEDULE, t)); 
+
+      /* Send a fetch (if BlockedOnGA) and dump event to log file */
+      blockThread(t);
+
+      IF_DEBUG(scheduler,
+              belch("--<< thread %ld (%p; %s) stopped, blocking on node %p with BQ: ", 
+                              t->id, t, whatNext_strs[t->what_next], t->block_info.closure);
+              if (t->block_info.closure!=(StgClosure*)NULL) print_bq(t->block_info.closure));
+
+#else /* !GRAN */
       /* don't need to do anything.  Either the thread is blocked on
        * I/O, in which case we'll have called addToBlockedQueue
        * previously, or it's blocked on an MVar or Blackhole, in which
        * case it'll be on the relevant queue already.
        */
       IF_DEBUG(scheduler,
-              fprintf(stderr, "thread %d stopped, ", t->id);
+              fprintf(stderr, "--<< thread %d (%p) stopped ", t->id, t);
               printThreadBlockage(t);
               fprintf(stderr, "\n"));
+
+      /* Only for dumping event to log file 
+        ToDo: do I need this in GranSim, too?
+      blockThread(t);
+      */
+#endif
       threadPaused(t);
       break;
       
@@ -525,8 +1062,15 @@ schedule( void )
        * more main threads, we probably need to stop all the tasks until
        * we get a new one.
        */
-      IF_DEBUG(scheduler,belch("thread %ld finished", t->id));
-      t->whatNext = ThreadComplete;
+      IF_DEBUG(scheduler,belch("--++ thread %d (%p) finished", t->id, t));
+      t->what_next = ThreadComplete;
+#if defined(GRAN)
+      endThread(t, CurrentProc); // clean-up the thread
+#elif defined(PAR)
+      advisory_thread_count--;
+      if (RtsFlags.ParFlags.ParStats.Full) 
+       DumpEndEvent(CURRENT_PROC, t, rtsFalse /* not mandatory */);
+#endif
       break;
       
     default:
@@ -540,10 +1084,11 @@ schedule( void )
 #endif
 
 #ifdef SMP
-    if (ready_to_gc && n_free_capabilities == RtsFlags.ParFlags.nNodes) {
+    if (ready_to_gc && n_free_capabilities == RtsFlags.ParFlags.nNodes) 
 #else
-    if (ready_to_gc) {
+    if (ready_to_gc) 
 #endif
+      {
       /* everybody back, start the GC.
        * Could do it in this thread, or signal a condition var
        * to do it in another thread.  Either way, we need to
@@ -557,11 +1102,37 @@ schedule( void )
 #ifdef SMP
       pthread_cond_broadcast(&gc_pending_cond);
 #endif
+#if defined(GRAN)
+      /* add a ContinueThread event to continue execution of current thread */
+      new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc],
+               ContinueThread,
+               t, (StgClosure*)NULL, (rtsSpark*)NULL);
+      IF_GRAN_DEBUG(bq, 
+              fprintf(stderr, "GRAN: eventq and runnableq after Garbage collection:\n");
+              G_EVENTQ(0);
+              G_CURR_THREADQ(0))
+#endif /* GRAN */
     }
+#if defined(GRAN)
+  next_thread:
+    IF_GRAN_DEBUG(unused,
+                 print_eventq(EventHd));
+
+    event = get_next_event();
+
+#elif defined(PAR)
+  next_thread:
+    /* ToDo: wait for next message to arrive rather than busy wait */
+
+#else /* GRAN */
+  /* not any more
+  next_thread:
+    t = take_off_run_queue(END_TSO_QUEUE);
+  */
+#endif /* GRAN */
   } /* end of while(1) */
 }
 
-
 /* A hack for Hugs concurrency support.  Needs sanitisation (?) */
 void deleteAllThreads ( void )
 {
@@ -577,8 +1148,12 @@ void deleteAllThreads ( void )
   blocked_queue_hd = blocked_queue_tl = END_TSO_QUEUE;
 }
 
+/* startThread and  insertThread are now in GranSim.c -- HWL */
 
-/* -----------------------------------------------------------------------------
+//@node Suspend and Resume, Run queue code, Main scheduling loop, Main scheduling code
+//@subsection Suspend and Resume
+
+/* ---------------------------------------------------------------------------
  * Suspending & resuming Haskell threads.
  * 
  * When making a "safe" call to C (aka _ccall_GC), the task gives back
@@ -591,7 +1166,7 @@ void deleteAllThreads ( void )
  * duration of the call, on the susepended_ccalling_threads queue.  We
  * give out a token to the task, which it can use to resume the thread
  * on return from the C function.
- * -------------------------------------------------------------------------- */
+ * ------------------------------------------------------------------------- */
    
 StgInt
 suspendThread( Capability *cap )
@@ -660,17 +1235,18 @@ resumeThread( StgInt tok )
   return cap;
 }
 
-/* -----------------------------------------------------------------------------
+
+/* ---------------------------------------------------------------------------
  * Static functions
- * -------------------------------------------------------------------------- */
+ * ------------------------------------------------------------------------ */
 static void unblockThread(StgTSO *tso);
 
-/* -----------------------------------------------------------------------------
+/* ---------------------------------------------------------------------------
  * Comparing Thread ids.
  *
  * This is used from STG land in the implementation of the
  * instances of Eq/Ord for ThreadIds.
- * -------------------------------------------------------------------------- */
+ * ------------------------------------------------------------------------ */
 
 int cmp_thread(const StgTSO *tso1, const StgTSO *tso2) 
 { 
@@ -682,7 +1258,7 @@ int cmp_thread(const StgTSO *tso1, const StgTSO *tso2)
   return 0;
 }
 
-/* -----------------------------------------------------------------------------
+/* ---------------------------------------------------------------------------
    Create a new thread.
 
    The new thread starts with the given stack size.  Before the
@@ -692,38 +1268,74 @@ int cmp_thread(const StgTSO *tso1, const StgTSO *tso2)
 
    createGenThread() and createIOThread() (in SchedAPI.h) are
    convenient packaged versions of this function.
-   -------------------------------------------------------------------------- */
 
+   currently pri (priority) is only used in a GRAN setup -- HWL
+   ------------------------------------------------------------------------ */
+//@cindex createThread
+#if defined(GRAN)
+/*   currently pri (priority) is only used in a GRAN setup -- HWL */
+StgTSO *
+createThread(nat stack_size, StgInt pri)
+{
+  return createThread_(stack_size, rtsFalse, pri);
+}
+
+static StgTSO *
+createThread_(nat size, rtsBool have_lock, StgInt pri)
+{
+#else
 StgTSO *
-createThread(nat size)
+createThread(nat stack_size)
 {
-  return createThread_(size, rtsFalse);
+  return createThread_(stack_size, rtsFalse);
 }
 
 static StgTSO *
 createThread_(nat size, rtsBool have_lock)
 {
-  StgTSO *tso;
-  nat stack_size;
+#endif
+
+    StgTSO *tso;
+    nat stack_size;
+
+    /* First check whether we should create a thread at all */
+#if defined(PAR)
+  /* check that no more than RtsFlags.ParFlags.maxThreads threads are created */
+  if (advisory_thread_count >= RtsFlags.ParFlags.maxThreads) {
+    threadsIgnored++;
+    belch("{createThread}Daq ghuH: refusing to create another thread; no more than %d threads allowed (currently %d)",
+         RtsFlags.ParFlags.maxThreads, advisory_thread_count);
+    return END_TSO_QUEUE;
+  }
+  threadsCreated++;
+#endif
+
+#if defined(GRAN)
+  ASSERT(!RtsFlags.GranFlags.Light || CurrentProc==0);
+#endif
+
+  // ToDo: check whether size = stack_size - TSO_STRUCT_SIZEW
 
   /* catch ridiculously small stack sizes */
   if (size < MIN_STACK_WORDS + TSO_STRUCT_SIZEW) {
     size = MIN_STACK_WORDS + TSO_STRUCT_SIZEW;
   }
 
-  tso = (StgTSO *)allocate(size);
-  TICK_ALLOC_TSO(size-sizeofW(StgTSO),0);
-  
   stack_size = size - TSO_STRUCT_SIZEW;
 
+  tso = (StgTSO *)allocate(size);
+  TICK_ALLOC_TSO(size-TSO_STRUCT_SIZEW, 0);
+
   SET_HDR(tso, &TSO_info, CCS_MAIN);
-  tso->whatNext = ThreadEnterGHC;
-  
+#if defined(GRAN)
+  SET_GRAN_HDR(tso, ThisPE);
+#endif
+  tso->what_next     = ThreadEnterGHC;
+
   /* tso->id needs to be unique.  For now we use a heavyweight mutex to
-        protect the increment operation on next_thread_id.
-        In future, we could use an atomic increment instead.
-  */
-  
+   * protect the increment operation on next_thread_id.
+   * In future, we could use an atomic increment instead.
+   */
   if (!have_lock) { ACQUIRE_LOCK(&sched_mutex); }
   tso->id = next_thread_id++; 
   if (!have_lock) { RELEASE_LOCK(&sched_mutex); }
@@ -746,13 +1358,131 @@ createThread_(nat size, rtsBool have_lock)
   SET_HDR((StgClosure*)tso->sp,(StgInfoTable *)&stg_stop_thread_info,CCS_MAIN);
   tso->su = (StgUpdateFrame*)tso->sp;
 
+  IF_DEBUG(scheduler,belch("---- Initialised TSO %ld (%p), stack size = %lx words", 
+                          tso->id, tso, tso->stack_size));
+
+  // ToDo: check this
+#if defined(GRAN)
+  tso->link = END_TSO_QUEUE;
+  /* uses more flexible routine in GranSim */
+  insertThread(tso, CurrentProc);
+#else
+  /* In a non-GranSim setup the pushing of a TSO onto the runq is separated
+   * from its creation
+   */
+#endif
+
+#if defined(GRAN) || defined(PAR)
+  DumpGranEvent(GR_START,tso);
+#endif
+
+  /* Link the new thread on the global thread list.
+   */
+  tso->global_link = all_threads;
+  all_threads = tso;
+
+#if defined(GRAN)
+  tso->gran.pri = pri;
+# if defined(DEBUG)
+  tso->gran.magic = TSO_MAGIC; // debugging only
+# endif
+  tso->gran.sparkname   = 0;
+  tso->gran.startedat   = CURRENT_TIME; 
+  tso->gran.exported    = 0;
+  tso->gran.basicblocks = 0;
+  tso->gran.allocs      = 0;
+  tso->gran.exectime    = 0;
+  tso->gran.fetchtime   = 0;
+  tso->gran.fetchcount  = 0;
+  tso->gran.blocktime   = 0;
+  tso->gran.blockcount  = 0;
+  tso->gran.blockedat   = 0;
+  tso->gran.globalsparks = 0;
+  tso->gran.localsparks  = 0;
+  if (RtsFlags.GranFlags.Light)
+    tso->gran.clock  = Now; /* local clock */
+  else
+    tso->gran.clock  = 0;
+
+  IF_DEBUG(gran,printTSO(tso));
+#elif defined(PAR)
+# if defined(DEBUG)
+  tso->par.magic = TSO_MAGIC; // debugging only
+# endif
+  tso->par.sparkname   = 0;
+  tso->par.startedat   = CURRENT_TIME; 
+  tso->par.exported    = 0;
+  tso->par.basicblocks = 0;
+  tso->par.allocs      = 0;
+  tso->par.exectime    = 0;
+  tso->par.fetchtime   = 0;
+  tso->par.fetchcount  = 0;
+  tso->par.blocktime   = 0;
+  tso->par.blockcount  = 0;
+  tso->par.blockedat   = 0;
+  tso->par.globalsparks = 0;
+  tso->par.localsparks  = 0;
+#endif
+
+#if defined(GRAN)
+  globalGranStats.tot_threads_created++;
+  globalGranStats.threads_created_on_PE[CurrentProc]++;
+  globalGranStats.tot_sq_len += spark_queue_len(CurrentProc);
+  globalGranStats.tot_sq_probes++;
+#endif 
+
+#if defined(GRAN)
+  IF_GRAN_DEBUG(pri,
+               belch("==__ schedule: Created TSO %d (%p);",
+                     CurrentProc, tso, tso->id));
+#elif defined(PAR)
+    IF_PAR_DEBUG(verbose,
+                belch("==__ schedule: Created TSO %d (%p); %d threads active",
+                      tso->id, tso, advisory_thread_count));
+#else
   IF_DEBUG(scheduler,sched_belch("created thread %ld, stack size = %lx words", 
                                 tso->id, tso->stack_size));
+#endif    
   return tso;
 }
 
+/*
+  Turn a spark into a thread.
+  ToDo: fix for SMP (needs to acquire SCHED_MUTEX!)
+*/
+#if defined(PAR)
+//@cindex activateSpark
+StgTSO *
+activateSpark (rtsSpark spark) 
+{
+  StgTSO *tso;
+  
+  ASSERT(spark != (rtsSpark)NULL);
+  tso = createThread_(RtsFlags.GcFlags.initialStkSize, rtsTrue);
+  if (tso!=END_TSO_QUEUE) {
+    pushClosure(tso,spark);
+    PUSH_ON_RUN_QUEUE(tso);
+    advisory_thread_count++;
+
+    if (RtsFlags.ParFlags.ParStats.Full) {
+      //ASSERT(run_queue_hd == END_TSO_QUEUE); // I think ...
+      IF_PAR_DEBUG(verbose,
+                  belch("==^^ activateSpark: turning spark of closure %p (%s) into a thread",
+                        (StgClosure *)spark, info_type((StgClosure *)spark)));
+    }
+  } else {
+    barf("activateSpark: Cannot create TSO");
+  }
+  // ToDo: fwd info on local/global spark to thread -- HWL
+  // tso->gran.exported =  spark->exported;
+  // tso->gran.locked =   !spark->global;
+  // tso->gran.sparkname = spark->name;
+
+  return tso;
+}
+#endif
 
-/* -----------------------------------------------------------------------------
+/* ---------------------------------------------------------------------------
  * scheduleThread()
  *
  * scheduleThread puts a thread on the head of the runnable queue.
@@ -760,11 +1490,16 @@ createThread_(nat size, rtsBool have_lock)
  * The caller of scheduleThread must create the thread using e.g.
  * createThread and push an appropriate closure
  * on this thread's stack before the scheduler is invoked.
- * -------------------------------------------------------------------------- */
+ * ------------------------------------------------------------------------ */
 
 void
 scheduleThread(StgTSO *tso)
 {
+  if (tso==END_TSO_QUEUE){    
+    schedule();
+    return;
+  }
+
   ACQUIRE_LOCK(&sched_mutex);
 
   /* Put the new thread on the head of the runnable queue.  The caller
@@ -779,25 +1514,23 @@ scheduleThread(StgTSO *tso)
   RELEASE_LOCK(&sched_mutex);
 }
 
-
-/* -----------------------------------------------------------------------------
+/* ---------------------------------------------------------------------------
  * startTasks()
  *
  * Start up Posix threads to run each of the scheduler tasks.
  * I believe the task ids are not needed in the system as defined.
-  * KH @ 25/10/99
- * -------------------------------------------------------------------------- */
+ *  KH @ 25/10/99
+ * ------------------------------------------------------------------------ */
 
-#ifdef SMP
-static void *
+#if defined(PAR) || defined(SMP)
+void *
 taskStart( void *arg STG_UNUSED )
 {
-  schedule();
-  return NULL;
+  rts_evalNothing(NULL);
 }
 #endif
 
-/* -----------------------------------------------------------------------------
+/* ---------------------------------------------------------------------------
  * initScheduler()
  *
  * Initialise the scheduler.  This resets all the queues - if the
@@ -805,7 +1538,7 @@ taskStart( void *arg STG_UNUSED )
  * next pass.
  *
  * This now calls startTasks(), so should only be called once!  KH @ 25/10/99
- * -------------------------------------------------------------------------- */
+ * ------------------------------------------------------------------------ */
 
 #ifdef SMP
 static void
@@ -819,16 +1552,31 @@ term_handler(int sig STG_UNUSED)
 }
 #endif
 
-void initScheduler(void)
+//@cindex initScheduler
+void 
+initScheduler(void)
 {
+#if defined(GRAN)
+  nat i;
+
+  for (i=0; i<=MAX_PROC; i++) {
+    run_queue_hds[i]      = END_TSO_QUEUE;
+    run_queue_tls[i]      = END_TSO_QUEUE;
+    blocked_queue_hds[i]  = END_TSO_QUEUE;
+    blocked_queue_tls[i]  = END_TSO_QUEUE;
+    ccalling_threadss[i]  = END_TSO_QUEUE;
+  }
+#else
   run_queue_hd      = END_TSO_QUEUE;
   run_queue_tl      = END_TSO_QUEUE;
   blocked_queue_hd  = END_TSO_QUEUE;
   blocked_queue_tl  = END_TSO_QUEUE;
+#endif 
 
   suspended_ccalling_threads  = END_TSO_QUEUE;
 
   main_threads = NULL;
+  all_threads  = END_TSO_QUEUE;
 
   context_switch = 0;
   interrupted    = 0;
@@ -948,7 +1696,7 @@ exitScheduler( void )
    -------------------------------------------------------------------------- */
 
 /* -----------------------------------------------------------------------------
- * waitThread is the external interface for running a new computataion
+ * waitThread is the external interface for running a new computation
  * and waiting for the result.
  *
  * In the non-SMP case, we create a new main thread, push it on the 
@@ -990,6 +1738,13 @@ waitThread(StgTSO *tso, /*out*/StgClosure **ret)
   do {
     pthread_cond_wait(&m->wakeup, &sched_mutex);
   } while (m->stat == NoStatus);
+#elif defined(GRAN)
+  /* GranSim specific init */
+  CurrentTSO = m->tso;                // the TSO to run
+  procStatus[MainProc] = Busy;        // status of main PE
+  CurrentProc = MainProc;             // PE to run it on
+
+  schedule();
 #else
   schedule();
   ASSERT(m->stat != NoStatus);
@@ -1009,52 +1764,122 @@ waitThread(StgTSO *tso, /*out*/StgClosure **ret)
 
   return stat;
 }
-  
-/* -----------------------------------------------------------------------------
-   Debugging: why is a thread blocked
-   -------------------------------------------------------------------------- */
 
-#ifdef DEBUG
-void printThreadBlockage(StgTSO *tso)
+//@node Run queue code, Garbage Collextion Routines, Suspend and Resume, Main scheduling code
+//@subsection Run queue code 
+
+#if 0
+/* 
+   NB: In GranSim we have many run queues; run_queue_hd is actually a macro
+       unfolding to run_queue_hds[CurrentProc], thus CurrentProc is an
+       implicit global variable that has to be correct when calling these
+       fcts -- HWL 
+*/
+
+/* Put the new thread on the head of the runnable queue.
+ * The caller of createThread better push an appropriate closure
+ * on this thread's stack before the scheduler is invoked.
+ */
+static /* inline */ void
+add_to_run_queue(tso)
+StgTSO* tso; 
 {
-  switch (tso->why_blocked) {
-  case BlockedOnRead:
-    fprintf(stderr,"blocked on read from fd %d", tso->block_info.fd);
-    break;
-  case BlockedOnWrite:
-    fprintf(stderr,"blocked on write to fd %d", tso->block_info.fd);
-    break;
-  case BlockedOnDelay:
-    fprintf(stderr,"blocked on delay of %d ms", tso->block_info.delay);
-    break;
-  case BlockedOnMVar:
-    fprintf(stderr,"blocked on an MVar");
-    break;
-  case BlockedOnException:
-    fprintf(stderr,"blocked on delivering an exception to thread %d",
-           tso->block_info.tso->id);
-    break;
-  case BlockedOnBlackHole:
-    fprintf(stderr,"blocked on a black hole");
-    break;
-  case NotBlocked:
-    fprintf(stderr,"not blocked");
-    break;
+  ASSERT(tso!=run_queue_hd && tso!=run_queue_tl);
+  tso->link = run_queue_hd;
+  run_queue_hd = tso;
+  if (run_queue_tl == END_TSO_QUEUE) {
+    run_queue_tl = tso;
   }
 }
-#endif
 
-/* -----------------------------------------------------------------------------
-   Where are the roots that we know about?
+/* Put the new thread at the end of the runnable queue. */
+static /* inline */ void
+push_on_run_queue(tso)
+StgTSO* tso; 
+{
+  ASSERT(get_itbl((StgClosure *)tso)->type == TSO);
+  ASSERT(run_queue_hd!=NULL && run_queue_tl!=NULL);
+  ASSERT(tso!=run_queue_hd && tso!=run_queue_tl);
+  if (run_queue_hd == END_TSO_QUEUE) {
+    run_queue_hd = tso;
+  } else {
+    run_queue_tl->link = tso;
+  }
+  run_queue_tl = tso;
+}
 
-        - all the threads on the runnable queue
-        - all the threads on the blocked queue
-       - all the thread currently executing a _ccall_GC
-        - all the "main threads"
-     
-   -------------------------------------------------------------------------- */
+/* 
+   Should be inlined because it's used very often in schedule.  The tso
+   argument is actually only needed in GranSim, where we want to have the
+   possibility to schedule *any* TSO on the run queue, irrespective of the
+   actual ordering. Therefore, if tso is not the nil TSO then we traverse
+   the run queue and dequeue the tso, adjusting the links in the queue. 
+*/
+//@cindex take_off_run_queue
+static /* inline */ StgTSO*
+take_off_run_queue(StgTSO *tso) {
+  StgTSO *t, *prev;
 
-/* This has to be protected either by the scheduler monitor, or by the
+  /* 
+     qetlaHbogh Qu' ngaSbogh ghomDaQ {tso} yIteq!
+
+     if tso is specified, unlink that tso from the run_queue (doesn't have
+     to be at the beginning of the queue); GranSim only 
+  */
+  if (tso!=END_TSO_QUEUE) {
+    /* find tso in queue */
+    for (t=run_queue_hd, prev=END_TSO_QUEUE; 
+        t!=END_TSO_QUEUE && t!=tso;
+        prev=t, t=t->link) 
+      /* nothing */ ;
+    ASSERT(t==tso);
+    /* now actually dequeue the tso */
+    if (prev!=END_TSO_QUEUE) {
+      ASSERT(run_queue_hd!=t);
+      prev->link = t->link;
+    } else {
+      /* t is at beginning of thread queue */
+      ASSERT(run_queue_hd==t);
+      run_queue_hd = t->link;
+    }
+    /* t is at end of thread queue */
+    if (t->link==END_TSO_QUEUE) {
+      ASSERT(t==run_queue_tl);
+      run_queue_tl = prev;
+    } else {
+      ASSERT(run_queue_tl!=t);
+    }
+    t->link = END_TSO_QUEUE;
+  } else {
+    /* take tso from the beginning of the queue; std concurrent code */
+    t = run_queue_hd;
+    if (t != END_TSO_QUEUE) {
+      run_queue_hd = t->link;
+      t->link = END_TSO_QUEUE;
+      if (run_queue_hd == END_TSO_QUEUE) {
+       run_queue_tl = END_TSO_QUEUE;
+      }
+    }
+  }
+  return t;
+}
+
+#endif /* 0 */
+
+//@node Garbage Collextion Routines, Blocking Queue Routines, Run queue code, Main scheduling code
+//@subsection Garbage Collextion Routines
+
+/* ---------------------------------------------------------------------------
+   Where are the roots that we know about?
+
+        - all the threads on the runnable queue
+        - all the threads on the blocked queue
+       - all the thread currently executing a _ccall_GC
+        - all the "main threads"
+     
+   ------------------------------------------------------------------------ */
+
+/* This has to be protected either by the scheduler monitor, or by the
        garbage collection monitor (probably the latter).
        KH @ 25/10/99
 */
@@ -1063,17 +1888,46 @@ static void GetRoots(void)
 {
   StgMainThread *m;
 
-  run_queue_hd      = (StgTSO *)MarkRoot((StgClosure *)run_queue_hd);
-  run_queue_tl      = (StgTSO *)MarkRoot((StgClosure *)run_queue_tl);
+#if defined(GRAN)
+  {
+    nat i;
+    for (i=0; i<=RtsFlags.GranFlags.proc; i++) {
+      if ((run_queue_hds[i] != END_TSO_QUEUE) && ((run_queue_hds[i] != NULL)))
+       run_queue_hds[i]    = (StgTSO *)MarkRoot((StgClosure *)run_queue_hds[i]);
+      if ((run_queue_tls[i] != END_TSO_QUEUE) && ((run_queue_tls[i] != NULL)))
+       run_queue_tls[i]    = (StgTSO *)MarkRoot((StgClosure *)run_queue_tls[i]);
+      
+      if ((blocked_queue_hds[i] != END_TSO_QUEUE) && ((blocked_queue_hds[i] != NULL)))
+       blocked_queue_hds[i] = (StgTSO *)MarkRoot((StgClosure *)blocked_queue_hds[i]);
+      if ((blocked_queue_tls[i] != END_TSO_QUEUE) && ((blocked_queue_tls[i] != NULL)))
+       blocked_queue_tls[i] = (StgTSO *)MarkRoot((StgClosure *)blocked_queue_tls[i]);
+      if ((ccalling_threadss[i] != END_TSO_QUEUE) && ((ccalling_threadss[i] != NULL)))
+       ccalling_threadss[i] = (StgTSO *)MarkRoot((StgClosure *)ccalling_threadss[i]);
+    }
+  }
+
+  markEventQueue();
 
-  blocked_queue_hd  = (StgTSO *)MarkRoot((StgClosure *)blocked_queue_hd);
-  blocked_queue_tl  = (StgTSO *)MarkRoot((StgClosure *)blocked_queue_tl);
+#else /* !GRAN */
+  if (run_queue_hd != END_TSO_QUEUE) {
+    ASSERT(run_queue_tl != END_TSO_QUEUE);
+    run_queue_hd      = (StgTSO *)MarkRoot((StgClosure *)run_queue_hd);
+    run_queue_tl      = (StgTSO *)MarkRoot((StgClosure *)run_queue_tl);
+  }
+
+  if (blocked_queue_hd != END_TSO_QUEUE) {
+    ASSERT(blocked_queue_tl != END_TSO_QUEUE);
+    blocked_queue_hd  = (StgTSO *)MarkRoot((StgClosure *)blocked_queue_hd);
+    blocked_queue_tl  = (StgTSO *)MarkRoot((StgClosure *)blocked_queue_tl);
+  }
+#endif 
 
   for (m = main_threads; m != NULL; m = m->link) {
     m->tso = (StgTSO *)MarkRoot((StgClosure *)m->tso);
   }
-  suspended_ccalling_threads = 
-    (StgTSO *)MarkRoot((StgClosure *)suspended_ccalling_threads);
+  if (suspended_ccalling_threads != END_TSO_QUEUE)
+    suspended_ccalling_threads = 
+      (StgTSO *)MarkRoot((StgClosure *)suspended_ccalling_threads);
 
 #if defined(SMP) || defined(PAR) || defined(GRAN)
   markSparkQueue();
@@ -1119,9 +1973,10 @@ performGCWithRoots(void (*get_roots)(void))
 /* -----------------------------------------------------------------------------
    Stack overflow
 
-   If the thread has reached its maximum stack size,
-   then bomb out.  Otherwise relocate the TSO into a larger chunk of
-   memory and adjust its stack size appropriately.
+   If the thread has reached its maximum stack size, then raise the
+   StackOverflow exception in the offending thread.  Otherwise
+   relocate the TSO into a larger chunk of memory and adjust its stack
+   size appropriately.
    -------------------------------------------------------------------------- */
 
 static StgTSO *
@@ -1131,18 +1986,22 @@ threadStackOverflow(StgTSO *tso)
   StgPtr new_sp;
   StgTSO *dest;
 
+  IF_DEBUG(sanity,checkTSO(tso));
   if (tso->stack_size >= tso->max_stack_size) {
-#if 0
-    /* If we're debugging, just print out the top of the stack */
-    printStackChunk(tso->sp, stg_min(tso->stack+tso->stack_size, 
-                                    tso->sp+64));
-#endif
+
+    IF_DEBUG(gc,
+            belch("@@ threadStackOverflow of TSO %d (%p): stack too large (now %ld; max is %ld",
+                  tso->id, tso, tso->stack_size, tso->max_stack_size);
+            /* If we're debugging, just print out the top of the stack */
+            printStackChunk(tso->sp, stg_min(tso->stack+tso->stack_size, 
+                                             tso->sp+64)));
+
 #ifdef INTERPRETER
     fprintf(stderr, "fatal: stack overflow in Hugs; aborting\n" );
     exit(1);
 #else
     /* Send this thread the StackOverflow exception */
-    raiseAsync(tso, (StgClosure *)&stackOverflow_closure);
+    raiseAsync(tso, (StgClosure *)stackOverflow_closure);
 #endif
     return tso;
   }
@@ -1178,37 +2037,163 @@ threadStackOverflow(StgTSO *tso)
   /* and relocate the update frame list */
   relocate_TSO(tso, dest);
 
-  /* Mark the old one as dead so we don't try to scavenge it during
-   * garbage collection (the TSO will likely be on a mutables list in
-   * some generation, but it'll get collected soon enough).  It's
-   * important to set the sp and su values to just beyond the end of
-   * the stack, so we don't attempt to scavenge any part of the dead
-   * TSO's stack.
+  /* Mark the old TSO as relocated.  We have to check for relocated
+   * TSOs in the garbage collector and any primops that deal with TSOs.
+   *
+   * It's important to set the sp and su values to just beyond the end
+   * of the stack, so we don't attempt to scavenge any part of the
+   * dead TSO's stack.
    */
-  tso->whatNext = ThreadKilled;
+  tso->what_next = ThreadRelocated;
+  tso->link = dest;
   tso->sp = (P_)&(tso->stack[tso->stack_size]);
   tso->su = (StgUpdateFrame *)tso->sp;
   tso->why_blocked = NotBlocked;
   dest->mut_link = NULL;
 
+  IF_PAR_DEBUG(verbose,
+              belch("@@ threadStackOverflow of TSO %d (now at %p): stack size increased to %ld",
+                    tso->id, tso, tso->stack_size);
+              /* If we're debugging, just print out the top of the stack */
+              printStackChunk(tso->sp, stg_min(tso->stack+tso->stack_size, 
+                                               tso->sp+64)));
+  
   IF_DEBUG(sanity,checkTSO(tso));
 #if 0
   IF_DEBUG(scheduler,printTSO(dest));
 #endif
 
-#if 0
-  /* This will no longer work: KH */
-  if (tso == MainTSO) { /* hack */
-      MainTSO = dest;
-  }
-#endif
   return dest;
 }
 
-/* -----------------------------------------------------------------------------
+//@node Blocking Queue Routines, Exception Handling Routines, Garbage Collextion Routines, Main scheduling code
+//@subsection Blocking Queue Routines
+
+/* ---------------------------------------------------------------------------
    Wake up a queue that was blocked on some resource.
-   -------------------------------------------------------------------------- */
+   ------------------------------------------------------------------------ */
+
+/* ToDo: check push_on_run_queue vs. PUSH_ON_RUN_QUEUE */
+
+#if defined(GRAN)
+static inline void
+unblockCount ( StgBlockingQueueElement *bqe, StgClosure *node )
+{
+}
+#elif defined(PAR)
+static inline void
+unblockCount ( StgBlockingQueueElement *bqe, StgClosure *node )
+{
+  /* write RESUME events to log file and
+     update blocked and fetch time (depending on type of the orig closure) */
+  if (RtsFlags.ParFlags.ParStats.Full) {
+    DumpRawGranEvent(CURRENT_PROC, CURRENT_PROC, 
+                    GR_RESUME, ((StgTSO *)bqe), ((StgTSO *)bqe)->block_info.closure,
+                    0, 0 /* spark_queue_len(ADVISORY_POOL) */);
+
+    switch (get_itbl(node)->type) {
+       case FETCH_ME_BQ:
+         ((StgTSO *)bqe)->par.fetchtime += CURRENT_TIME-((StgTSO *)bqe)->par.blockedat;
+         break;
+       case RBH:
+       case FETCH_ME:
+       case BLACKHOLE_BQ:
+         ((StgTSO *)bqe)->par.blocktime += CURRENT_TIME-((StgTSO *)bqe)->par.blockedat;
+         break;
+       default:
+         barf("{unblockOneLocked}Daq Qagh: unexpected closure in blocking queue");
+       }
+      }
+}
+#endif
+
+#if defined(GRAN)
+static StgBlockingQueueElement *
+unblockOneLocked(StgBlockingQueueElement *bqe, StgClosure *node)
+{
+    StgTSO *tso;
+    PEs node_loc, tso_loc;
+
+    node_loc = where_is(node); // should be lifted out of loop
+    tso = (StgTSO *)bqe;  // wastes an assignment to get the type right
+    tso_loc = where_is((StgClosure *)tso);
+    if (IS_LOCAL_TO(PROCS(node),tso_loc)) { // TSO is local
+      /* !fake_fetch => TSO is on CurrentProc is same as IS_LOCAL_TO */
+      ASSERT(CurrentProc!=node_loc || tso_loc==CurrentProc);
+      CurrentTime[CurrentProc] += RtsFlags.GranFlags.Costs.lunblocktime;
+      // insertThread(tso, node_loc);
+      new_event(tso_loc, tso_loc, CurrentTime[CurrentProc],
+               ResumeThread,
+               tso, node, (rtsSpark*)NULL);
+      tso->link = END_TSO_QUEUE; // overwrite link just to be sure 
+      // len_local++;
+      // len++;
+    } else { // TSO is remote (actually should be FMBQ)
+      CurrentTime[CurrentProc] += RtsFlags.GranFlags.Costs.mpacktime +
+                                  RtsFlags.GranFlags.Costs.gunblocktime +
+                                 RtsFlags.GranFlags.Costs.latency;
+      new_event(tso_loc, CurrentProc, CurrentTime[CurrentProc],
+               UnblockThread,
+               tso, node, (rtsSpark*)NULL);
+      tso->link = END_TSO_QUEUE; // overwrite link just to be sure 
+      // len++;
+    }
+    /* the thread-queue-overhead is accounted for in either Resume or UnblockThread */
+    IF_GRAN_DEBUG(bq,
+                 fprintf(stderr," %s TSO %d (%p) [PE %d] (block_info.closure=%p) (next=%p) ,",
+                         (node_loc==tso_loc ? "Local" : "Global"), 
+                         tso->id, tso, CurrentProc, tso->block_info.closure, tso->link));
+    tso->block_info.closure = NULL;
+    IF_DEBUG(scheduler,belch("-- Waking up thread %ld (%p)", 
+                            tso->id, tso));
+}
+#elif defined(PAR)
+static StgBlockingQueueElement *
+unblockOneLocked(StgBlockingQueueElement *bqe, StgClosure *node)
+{
+    StgBlockingQueueElement *next;
+
+    switch (get_itbl(bqe)->type) {
+    case TSO:
+      ASSERT(((StgTSO *)bqe)->why_blocked != NotBlocked);
+      /* if it's a TSO just push it onto the run_queue */
+      next = bqe->link;
+      // ((StgTSO *)bqe)->link = END_TSO_QUEUE; // debugging?
+      PUSH_ON_RUN_QUEUE((StgTSO *)bqe); 
+      THREAD_RUNNABLE();
+      unblockCount(bqe, node);
+      /* reset blocking status after dumping event */
+      ((StgTSO *)bqe)->why_blocked = NotBlocked;
+      break;
+
+    case BLOCKED_FETCH:
+      /* if it's a BLOCKED_FETCH put it on the PendingFetches list */
+      next = bqe->link;
+      bqe->link = PendingFetches;
+      PendingFetches = bqe;
+      break;
+
+# if defined(DEBUG)
+      /* can ignore this case in a non-debugging setup; 
+        see comments on RBHSave closures above */
+    case CONSTR:
+      /* check that the closure is an RBHSave closure */
+      ASSERT(get_itbl((StgClosure *)bqe) == &RBH_Save_0_info ||
+            get_itbl((StgClosure *)bqe) == &RBH_Save_1_info ||
+            get_itbl((StgClosure *)bqe) == &RBH_Save_2_info);
+      break;
 
+    default:
+      barf("{unblockOneLocked}Daq Qagh: Unexpected IP (%#lx; %s) in blocking queue at %#lx\n",
+          get_itbl((StgClosure *)bqe), info_type((StgClosure *)bqe), 
+          (StgClosure *)bqe);
+# endif
+    }
+  // IF_DEBUG(scheduler,sched_belch("waking up thread %ld", tso->id));
+  return next;
+}
+
+#else /* !GRAN && !PAR */
 static StgTSO *
 unblockOneLocked(StgTSO *tso)
 {
@@ -1223,7 +2208,18 @@ unblockOneLocked(StgTSO *tso)
   IF_DEBUG(scheduler,sched_belch("waking up thread %ld", tso->id));
   return next;
 }
+#endif
 
+#if defined(GRAN) || defined(PAR)
+inline StgBlockingQueueElement *
+unblockOne(StgBlockingQueueElement *bqe, StgClosure *node)
+{
+  ACQUIRE_LOCK(&sched_mutex);
+  bqe = unblockOneLocked(bqe, node);
+  RELEASE_LOCK(&sched_mutex);
+  return bqe;
+}
+#else
 inline StgTSO *
 unblockOne(StgTSO *tso)
 {
@@ -1232,7 +2228,114 @@ unblockOne(StgTSO *tso)
   RELEASE_LOCK(&sched_mutex);
   return tso;
 }
+#endif
+
+#if defined(GRAN)
+void 
+awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node)
+{
+  StgBlockingQueueElement *bqe;
+  PEs node_loc;
+  nat len = 0; 
+
+  IF_GRAN_DEBUG(bq, 
+               belch("## AwBQ for node %p on PE %d @ %ld by TSO %d (%p): ", \
+                     node, CurrentProc, CurrentTime[CurrentProc], 
+                     CurrentTSO->id, CurrentTSO));
+
+  node_loc = where_is(node);
+
+  ASSERT(get_itbl(q)->type == TSO ||   // q is either a TSO or an RBHSave
+        get_itbl(q)->type == CONSTR); // closure (type constructor)
+  ASSERT(is_unique(node));
+
+  /* FAKE FETCH: magically copy the node to the tso's proc;
+     no Fetch necessary because in reality the node should not have been 
+     moved to the other PE in the first place
+  */
+  if (CurrentProc!=node_loc) {
+    IF_GRAN_DEBUG(bq, 
+                 belch("## node %p is on PE %d but CurrentProc is %d (TSO %d); assuming fake fetch and adjusting bitmask (old: %#x)",
+                       node, node_loc, CurrentProc, CurrentTSO->id, 
+                       // CurrentTSO, where_is(CurrentTSO),
+                       node->header.gran.procs));
+    node->header.gran.procs = (node->header.gran.procs) | PE_NUMBER(CurrentProc);
+    IF_GRAN_DEBUG(bq, 
+                 belch("## new bitmask of node %p is %#x",
+                       node, node->header.gran.procs));
+    if (RtsFlags.GranFlags.GranSimStats.Global) {
+      globalGranStats.tot_fake_fetches++;
+    }
+  }
+
+  bqe = q;
+  // ToDo: check: ASSERT(CurrentProc==node_loc);
+  while (get_itbl(bqe)->type==TSO) { // q != END_TSO_QUEUE) {
+    //next = bqe->link;
+    /* 
+       bqe points to the current element in the queue
+       next points to the next element in the queue
+    */
+    //tso = (StgTSO *)bqe;  // wastes an assignment to get the type right
+    //tso_loc = where_is(tso);
+    len++;
+    bqe = unblockOneLocked(bqe, node);
+  }
+
+  /* if this is the BQ of an RBH, we have to put back the info ripped out of
+     the closure to make room for the anchor of the BQ */
+  if (bqe!=END_BQ_QUEUE) {
+    ASSERT(get_itbl(node)->type == RBH && get_itbl(bqe)->type == CONSTR);
+    /*
+    ASSERT((info_ptr==&RBH_Save_0_info) ||
+          (info_ptr==&RBH_Save_1_info) ||
+          (info_ptr==&RBH_Save_2_info));
+    */
+    /* cf. convertToRBH in RBH.c for writing the RBHSave closure */
+    ((StgRBH *)node)->blocking_queue = (StgBlockingQueueElement *)((StgRBHSave *)bqe)->payload[0];
+    ((StgRBH *)node)->mut_link       = (StgMutClosure *)((StgRBHSave *)bqe)->payload[1];
+
+    IF_GRAN_DEBUG(bq,
+                 belch("## Filled in RBH_Save for %p (%s) at end of AwBQ",
+                       node, info_type(node)));
+  }
+
+  /* statistics gathering */
+  if (RtsFlags.GranFlags.GranSimStats.Global) {
+    // globalGranStats.tot_bq_processing_time += bq_processing_time;
+    globalGranStats.tot_bq_len += len;      // total length of all bqs awakened
+    // globalGranStats.tot_bq_len_local += len_local;  // same for local TSOs only
+    globalGranStats.tot_awbq++;             // total no. of bqs awakened
+  }
+  IF_GRAN_DEBUG(bq,
+               fprintf(stderr,"## BQ Stats of %p: [%d entries] %s\n",
+                       node, len, (bqe!=END_BQ_QUEUE) ? "RBH" : ""));
+}
+#elif defined(PAR)
+void 
+awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node)
+{
+  StgBlockingQueueElement *bqe, *next;
+
+  ACQUIRE_LOCK(&sched_mutex);
+
+  IF_PAR_DEBUG(verbose, 
+              belch("## AwBQ for node %p on [%x]: ",
+                    node, mytid));
+
+  ASSERT(get_itbl(q)->type == TSO ||           
+        get_itbl(q)->type == BLOCKED_FETCH || 
+        get_itbl(q)->type == CONSTR); 
+
+  bqe = q;
+  while (get_itbl(bqe)->type==TSO || 
+        get_itbl(bqe)->type==BLOCKED_FETCH) {
+    bqe = unblockOneLocked(bqe, node);
+  }
+  RELEASE_LOCK(&sched_mutex);
+}
 
+#else   /* !GRAN && !PAR */
 void
 awakenBlockedQueue(StgTSO *tso)
 {
@@ -1242,11 +2345,15 @@ awakenBlockedQueue(StgTSO *tso)
   }
   RELEASE_LOCK(&sched_mutex);
 }
+#endif
 
-/* -----------------------------------------------------------------------------
+//@node Exception Handling Routines, Debugging Routines, Blocking Queue Routines, Main scheduling code
+//@subsection Exception Handling Routines
+
+/* ---------------------------------------------------------------------------
    Interrupt execution
    - usually called inside a signal handler so it mustn't do anything fancy.   
-   -------------------------------------------------------------------------- */
+   ------------------------------------------------------------------------ */
 
 void
 interruptStgRts(void)
@@ -1260,8 +2367,121 @@ interruptStgRts(void)
 
    This is for use when we raise an exception in another thread, which
    may be blocked.
+   This has nothing to do with the UnblockThread event in GranSim. -- HWL
    -------------------------------------------------------------------------- */
 
+#if defined(GRAN) || defined(PAR)
+/*
+  NB: only the type of the blocking queue is different in GranSim and GUM
+      the operations on the queue-elements are the same
+      long live polymorphism!
+*/
+static void
+unblockThread(StgTSO *tso)
+{
+  StgBlockingQueueElement *t, **last;
+
+  ACQUIRE_LOCK(&sched_mutex);
+  switch (tso->why_blocked) {
+
+  case NotBlocked:
+    return;  /* not blocked */
+
+  case BlockedOnMVar:
+    ASSERT(get_itbl(tso->block_info.closure)->type == MVAR);
+    {
+      StgBlockingQueueElement *last_tso = END_BQ_QUEUE;
+      StgMVar *mvar = (StgMVar *)(tso->block_info.closure);
+
+      last = (StgBlockingQueueElement **)&mvar->head;
+      for (t = (StgBlockingQueueElement *)mvar->head; 
+          t != END_BQ_QUEUE; 
+          last = &t->link, last_tso = t, t = t->link) {
+       if (t == (StgBlockingQueueElement *)tso) {
+         *last = (StgBlockingQueueElement *)tso->link;
+         if (mvar->tail == tso) {
+           mvar->tail = (StgTSO *)last_tso;
+         }
+         goto done;
+       }
+      }
+      barf("unblockThread (MVAR): TSO not found");
+    }
+
+  case BlockedOnBlackHole:
+    ASSERT(get_itbl(tso->block_info.closure)->type == BLACKHOLE_BQ);
+    {
+      StgBlockingQueue *bq = (StgBlockingQueue *)(tso->block_info.closure);
+
+      last = &bq->blocking_queue;
+      for (t = bq->blocking_queue; 
+          t != END_BQ_QUEUE; 
+          last = &t->link, t = t->link) {
+       if (t == (StgBlockingQueueElement *)tso) {
+         *last = (StgBlockingQueueElement *)tso->link;
+         goto done;
+       }
+      }
+      barf("unblockThread (BLACKHOLE): TSO not found");
+    }
+
+  case BlockedOnException:
+    {
+      StgTSO *target  = tso->block_info.tso;
+
+      ASSERT(get_itbl(target)->type == TSO);
+      ASSERT(target->blocked_exceptions != NULL);
+
+      last = (StgBlockingQueueElement **)&target->blocked_exceptions;
+      for (t = (StgBlockingQueueElement *)target->blocked_exceptions; 
+          t != END_BQ_QUEUE; 
+          last = &t->link, t = t->link) {
+       ASSERT(get_itbl(t)->type == TSO);
+       if (t == (StgBlockingQueueElement *)tso) {
+         *last = (StgBlockingQueueElement *)tso->link;
+         goto done;
+       }
+      }
+      barf("unblockThread (Exception): TSO not found");
+    }
+
+  case BlockedOnDelay:
+  case BlockedOnRead:
+  case BlockedOnWrite:
+    {
+      StgBlockingQueueElement *prev = NULL;
+      for (t = (StgBlockingQueueElement *)blocked_queue_hd; t != END_BQ_QUEUE; 
+          prev = t, t = t->link) {
+       if (t == (StgBlockingQueueElement *)tso) {
+         if (prev == NULL) {
+           blocked_queue_hd = (StgTSO *)t->link;
+           if ((StgBlockingQueueElement *)blocked_queue_tl == t) {
+             blocked_queue_tl = END_TSO_QUEUE;
+           }
+         } else {
+           prev->link = t->link;
+           if ((StgBlockingQueueElement *)blocked_queue_tl == t) {
+             blocked_queue_tl = (StgTSO *)prev;
+           }
+         }
+         goto done;
+       }
+      }
+      barf("unblockThread (I/O): TSO not found");
+    }
+
+  default:
+    barf("unblockThread");
+  }
+
+ done:
+  tso->link = END_TSO_QUEUE;
+  tso->why_blocked = NotBlocked;
+  tso->block_info.closure = NULL;
+  PUSH_ON_RUN_QUEUE(tso);
+  RELEASE_LOCK(&sched_mutex);
+}
+#else
 static void
 unblockThread(StgTSO *tso)
 {
@@ -1364,6 +2584,7 @@ unblockThread(StgTSO *tso)
   PUSH_ON_RUN_QUEUE(tso);
   RELEASE_LOCK(&sched_mutex);
 }
+#endif
 
 /* -----------------------------------------------------------------------------
  * raiseAsync()
@@ -1410,7 +2631,7 @@ raiseAsync(StgTSO *tso, StgClosure *exception)
   StgPtr          sp = tso->sp;
   
   /* Thread already dead? */
-  if (tso->whatNext == ThreadComplete || tso->whatNext == ThreadKilled) {
+  if (tso->what_next == ThreadComplete || tso->what_next == ThreadKilled) {
     return;
   }
 
@@ -1434,25 +2655,27 @@ raiseAsync(StgTSO *tso, StgClosure *exception)
     StgAP_UPD * ap;
 
     /* If we find a CATCH_FRAME, and we've got an exception to raise,
-     * then build PAP(handler,exception), and leave it on top of
-     * the stack ready to enter.
+     * then build PAP(handler,exception,realworld#), and leave it on
+     * top of the stack ready to enter.
      */
     if (get_itbl(su)->type == CATCH_FRAME && exception != NULL) {
       StgCatchFrame *cf = (StgCatchFrame *)su;
       /* we've got an exception to raise, so let's pass it to the
        * handler in this frame.
        */
-      ap = (StgAP_UPD *)allocate(sizeofW(StgPAP) + 1);
-      TICK_ALLOC_UPD_PAP(2,0);
+      ap = (StgAP_UPD *)allocate(sizeofW(StgPAP) + 2);
+      TICK_ALLOC_UPD_PAP(3,0);
       SET_HDR(ap,&PAP_info,cf->header.prof.ccs);
              
-      ap->n_args = 1;
-      ap->fun = cf->handler;
+      ap->n_args = 2;
+      ap->fun = cf->handler;   /* :: Exception -> IO a */
       ap->payload[0] = (P_)exception;
+      ap->payload[1] = ARG_TAG(0); /* realworld token */
 
-      /* sp currently points to the word above the CATCH_FRAME on the stack.
+      /* throw away the stack from Sp up to and including the
+       * CATCH_FRAME.
        */
-      sp += sizeofW(StgCatchFrame);
+      sp = (P_)su + sizeofW(StgCatchFrame) - 1; 
       tso->su = cf->link;
 
       /* Restore the blocked/unblocked state for asynchronous exceptions
@@ -1477,7 +2700,7 @@ raiseAsync(StgTSO *tso, StgClosure *exception)
        */
       sp[0] = (W_)ap;
       tso->sp = sp;
-      tso->whatNext = ThreadEnterGHC;
+      tso->what_next = ThreadEnterGHC;
       return;
     }
 
@@ -1563,7 +2786,7 @@ raiseAsync(StgTSO *tso, StgClosure *exception)
        o = (StgClosure *)allocate(sizeofW(StgClosure)+1);
        TICK_ALLOC_SE_THK(1,0);
        SET_HDR(o,&seq_info,su->header.prof.ccs /* ToDo */);
-       payloadCPtr(o,0) = (StgClosure *)ap;
+       o->payload[0] = (StgClosure *)ap;
        
        IF_DEBUG(scheduler,
                 fprintf(stderr,  "scheduler: Built ");
@@ -1581,7 +2804,7 @@ raiseAsync(StgTSO *tso, StgClosure *exception)
       /* We've stripped the entire stack, the thread is now dead. */
       sp += sizeofW(StgStopFrame) - 1;
       sp[0] = (W_)exception;   /* save the exception */
-      tso->whatNext = ThreadKilled;
+      tso->what_next = ThreadKilled;
       tso->su = (StgUpdateFrame *)(sp+1);
       tso->sp = sp;
       return;
@@ -1594,10 +2817,282 @@ raiseAsync(StgTSO *tso, StgClosure *exception)
 }
 
 /* -----------------------------------------------------------------------------
-   Debuggery...
+   resurrectThreads is called after garbage collection on the list of
+   threads found to be garbage.  Each of these threads will be woken
+   up and sent a signal: BlockedOnDeadMVar if the thread was blocked
+   on an MVar, or NonTermination if the thread was blocked on a Black
+   Hole.
+   -------------------------------------------------------------------------- */
+
+void
+resurrectThreads( StgTSO *threads )
+{
+  StgTSO *tso, *next;
+
+  for (tso = threads; tso != END_TSO_QUEUE; tso = next) {
+    next = tso->global_link;
+    tso->global_link = all_threads;
+    all_threads = tso;
+    IF_DEBUG(scheduler, sched_belch("resurrecting thread %d", tso->id));
+
+    switch (tso->why_blocked) {
+    case BlockedOnMVar:
+    case BlockedOnException:
+      raiseAsync(tso,(StgClosure *)BlockedOnDeadMVar_closure);
+      break;
+    case BlockedOnBlackHole:
+      raiseAsync(tso,(StgClosure *)NonTermination_closure);
+      break;
+    case NotBlocked:
+      /* This might happen if the thread was blocked on a black hole
+       * belonging to a thread that we've just woken up (raiseAsync
+       * can wake up threads, remember...).
+       */
+      continue;
+    default:
+      barf("resurrectThreads: thread blocked in a strange way");
+    }
+  }
+}
+
+//@node Debugging Routines, Index, Exception Handling Routines, Main scheduling code
+//@subsection Debugging Routines
+
+/* -----------------------------------------------------------------------------
+   Debugging: why is a thread blocked
    -------------------------------------------------------------------------- */
 
 #ifdef DEBUG
+
+void
+printThreadBlockage(StgTSO *tso)
+{
+  switch (tso->why_blocked) {
+  case BlockedOnRead:
+    fprintf(stderr,"blocked on read from fd %d", tso->block_info.fd);
+    break;
+  case BlockedOnWrite:
+    fprintf(stderr,"blocked on write to fd %d", tso->block_info.fd);
+    break;
+  case BlockedOnDelay:
+#if defined(HAVE_SETITIMER) || defined(mingw32_TARGET_OS)
+    fprintf(stderr,"blocked on delay of %d ms", tso->block_info.delay);
+#else
+    fprintf(stderr,"blocked on delay of %d ms", 
+           tso->block_info.target - getourtimeofday());
+#endif
+    break;
+  case BlockedOnMVar:
+    fprintf(stderr,"blocked on an MVar");
+    break;
+  case BlockedOnException:
+    fprintf(stderr,"blocked on delivering an exception to thread %d",
+           tso->block_info.tso->id);
+    break;
+  case BlockedOnBlackHole:
+    fprintf(stderr,"blocked on a black hole");
+    break;
+  case NotBlocked:
+    fprintf(stderr,"not blocked");
+    break;
+#if defined(PAR)
+  case BlockedOnGA:
+    fprintf(stderr,"blocked on global address; local FM_BQ is %p (%s)",
+           tso->block_info.closure, info_type(tso->block_info.closure));
+    break;
+  case BlockedOnGA_NoSend:
+    fprintf(stderr,"blocked on global address (no send); local FM_BQ is %p (%s)",
+           tso->block_info.closure, info_type(tso->block_info.closure));
+    break;
+#endif
+  default:
+    barf("printThreadBlockage: strange tso->why_blocked: %d for TSO %d (%d)",
+        tso->why_blocked, tso->id, tso);
+  }
+}
+
+void
+printThreadStatus(StgTSO *tso)
+{
+  switch (tso->what_next) {
+  case ThreadKilled:
+    fprintf(stderr,"has been killed");
+    break;
+  case ThreadComplete:
+    fprintf(stderr,"has completed");
+    break;
+  default:
+    printThreadBlockage(tso);
+  }
+}
+
+void
+printAllThreads(void)
+{
+  StgTSO *t;
+
+  sched_belch("all threads:");
+  for (t = all_threads; t != END_TSO_QUEUE; t = t->global_link) {
+    fprintf(stderr, "\tthread %d is ", t->id);
+    printThreadStatus(t);
+    fprintf(stderr,"\n");
+  }
+}
+    
+/* 
+   Print a whole blocking queue attached to node (debugging only).
+*/
+//@cindex print_bq
+# if defined(PAR)
+void 
+print_bq (StgClosure *node)
+{
+  StgBlockingQueueElement *bqe;
+  StgTSO *tso;
+  rtsBool end;
+
+  fprintf(stderr,"## BQ of closure %p (%s): ",
+         node, info_type(node));
+
+  /* should cover all closures that may have a blocking queue */
+  ASSERT(get_itbl(node)->type == BLACKHOLE_BQ ||
+        get_itbl(node)->type == FETCH_ME_BQ ||
+        get_itbl(node)->type == RBH);
+    
+  ASSERT(node!=(StgClosure*)NULL);         // sanity check
+  /* 
+     NB: In a parallel setup a BQ of an RBH must end with an RBH_Save closure;
+  */
+  for (bqe = ((StgBlockingQueue*)node)->blocking_queue, end = (bqe==END_BQ_QUEUE);
+       !end; // iterate until bqe points to a CONSTR
+       end = (get_itbl(bqe)->type == CONSTR) || (bqe->link==END_BQ_QUEUE), bqe = end ? END_BQ_QUEUE : bqe->link) {
+    ASSERT(bqe != END_BQ_QUEUE);             // sanity check
+    ASSERT(bqe != (StgTSO*)NULL);            // sanity check
+    /* types of closures that may appear in a blocking queue */
+    ASSERT(get_itbl(bqe)->type == TSO ||           
+          get_itbl(bqe)->type == BLOCKED_FETCH || 
+          get_itbl(bqe)->type == CONSTR); 
+    /* only BQs of an RBH end with an RBH_Save closure */
+    ASSERT(get_itbl(bqe)->type != CONSTR || get_itbl(node)->type == RBH);
+
+    switch (get_itbl(bqe)->type) {
+    case TSO:
+      fprintf(stderr," TSO %d (%x),",
+             ((StgTSO *)bqe)->id, ((StgTSO *)bqe));
+      break;
+    case BLOCKED_FETCH:
+      fprintf(stderr," BF (node=%p, ga=((%x, %d, %x)),",
+             ((StgBlockedFetch *)bqe)->node, 
+             ((StgBlockedFetch *)bqe)->ga.payload.gc.gtid,
+             ((StgBlockedFetch *)bqe)->ga.payload.gc.slot,
+             ((StgBlockedFetch *)bqe)->ga.weight);
+      break;
+    case CONSTR:
+      fprintf(stderr," %s (IP %p),",
+             (get_itbl(bqe) == &RBH_Save_0_info ? "RBH_Save_0" :
+              get_itbl(bqe) == &RBH_Save_1_info ? "RBH_Save_1" :
+              get_itbl(bqe) == &RBH_Save_2_info ? "RBH_Save_2" :
+              "RBH_Save_?"), get_itbl(bqe));
+      break;
+    default:
+      barf("Unexpected closure type %s in blocking queue of %p (%s)",
+          info_type(bqe), node, info_type(node));
+      break;
+    }
+  } /* for */
+  fputc('\n', stderr);
+}
+# elif defined(GRAN)
+void 
+print_bq (StgClosure *node)
+{
+  StgBlockingQueueElement *bqe;
+  PEs node_loc, tso_loc;
+  rtsBool end;
+
+  /* should cover all closures that may have a blocking queue */
+  ASSERT(get_itbl(node)->type == BLACKHOLE_BQ ||
+        get_itbl(node)->type == FETCH_ME_BQ ||
+        get_itbl(node)->type == RBH);
+    
+  ASSERT(node!=(StgClosure*)NULL);         // sanity check
+  node_loc = where_is(node);
+
+  fprintf(stderr,"## BQ of closure %p (%s) on [PE %d]: ",
+         node, info_type(node), node_loc);
+
+  /* 
+     NB: In a parallel setup a BQ of an RBH must end with an RBH_Save closure;
+  */
+  for (bqe = ((StgBlockingQueue*)node)->blocking_queue, end = (bqe==END_BQ_QUEUE);
+       !end; // iterate until bqe points to a CONSTR
+       end = (get_itbl(bqe)->type == CONSTR) || (bqe->link==END_BQ_QUEUE), bqe = end ? END_BQ_QUEUE : bqe->link) {
+    ASSERT(bqe != END_BQ_QUEUE);             // sanity check
+    ASSERT(bqe != (StgBlockingQueueElement *)NULL);  // sanity check
+    /* types of closures that may appear in a blocking queue */
+    ASSERT(get_itbl(bqe)->type == TSO ||           
+          get_itbl(bqe)->type == CONSTR); 
+    /* only BQs of an RBH end with an RBH_Save closure */
+    ASSERT(get_itbl(bqe)->type != CONSTR || get_itbl(node)->type == RBH);
+
+    tso_loc = where_is((StgClosure *)bqe);
+    switch (get_itbl(bqe)->type) {
+    case TSO:
+      fprintf(stderr," TSO %d (%p) on [PE %d],",
+             ((StgTSO *)bqe)->id, (StgTSO *)bqe, tso_loc);
+      break;
+    case CONSTR:
+      fprintf(stderr," %s (IP %p),",
+             (get_itbl(bqe) == &RBH_Save_0_info ? "RBH_Save_0" :
+              get_itbl(bqe) == &RBH_Save_1_info ? "RBH_Save_1" :
+              get_itbl(bqe) == &RBH_Save_2_info ? "RBH_Save_2" :
+              "RBH_Save_?"), get_itbl(bqe));
+      break;
+    default:
+      barf("Unexpected closure type %s in blocking queue of %p (%s)",
+          info_type((StgClosure *)bqe), node, info_type(node));
+      break;
+    }
+  } /* for */
+  fputc('\n', stderr);
+}
+#else
+/* 
+   Nice and easy: only TSOs on the blocking queue
+*/
+void 
+print_bq (StgClosure *node)
+{
+  StgTSO *tso;
+
+  ASSERT(node!=(StgClosure*)NULL);         // sanity check
+  for (tso = ((StgBlockingQueue*)node)->blocking_queue;
+       tso != END_TSO_QUEUE; 
+       tso=tso->link) {
+    ASSERT(tso!=NULL && tso!=END_TSO_QUEUE);   // sanity check
+    ASSERT(get_itbl(tso)->type == TSO);  // guess what, sanity check
+    fprintf(stderr," TSO %d (%p),", tso->id, tso);
+  }
+  fputc('\n', stderr);
+}
+# endif
+
+#if defined(PAR)
+static nat
+run_queue_len(void)
+{
+  nat i;
+  StgTSO *tso;
+
+  for (i=0, tso=run_queue_hd; 
+       tso != END_TSO_QUEUE;
+       i++, tso=tso->link)
+    /* nothing */
+
+  return i;
+}
+#endif
+
 static void
 sched_belch(char *s, ...)
 {
@@ -1611,4 +3106,34 @@ sched_belch(char *s, ...)
   vfprintf(stderr, s, ap);
   fprintf(stderr, "\n");
 }
-#endif
+
+#endif /* DEBUG */
+
+
+//@node Index,  , Debugging Routines, Main scheduling code
+//@subsection Index
+
+//@index
+//* MainRegTable::  @cindex\s-+MainRegTable
+//* StgMainThread::  @cindex\s-+StgMainThread
+//* awaken_blocked_queue::  @cindex\s-+awaken_blocked_queue
+//* blocked_queue_hd::  @cindex\s-+blocked_queue_hd
+//* blocked_queue_tl::  @cindex\s-+blocked_queue_tl
+//* context_switch::  @cindex\s-+context_switch
+//* createThread::  @cindex\s-+createThread
+//* free_capabilities::  @cindex\s-+free_capabilities
+//* gc_pending_cond::  @cindex\s-+gc_pending_cond
+//* initScheduler::  @cindex\s-+initScheduler
+//* interrupted::  @cindex\s-+interrupted
+//* n_free_capabilities::  @cindex\s-+n_free_capabilities
+//* next_thread_id::  @cindex\s-+next_thread_id
+//* print_bq::  @cindex\s-+print_bq
+//* run_queue_hd::  @cindex\s-+run_queue_hd
+//* run_queue_tl::  @cindex\s-+run_queue_tl
+//* sched_mutex::  @cindex\s-+sched_mutex
+//* schedule::  @cindex\s-+schedule
+//* take_off_run_queue::  @cindex\s-+take_off_run_queue
+//* task_ids::  @cindex\s-+task_ids
+//* term_mutex::  @cindex\s-+term_mutex
+//* thread_ready_cond::  @cindex\s-+thread_ready_cond
+//@end index