rts/Sparks.c

   1 /* ---------------------------------------------------------------------------
   2  *
   3  * (c) The GHC Team, 2000-2006
   4  *
   5  * Sparking support for PARALLEL_HASKELL and THREADED_RTS versions of the RTS.
   6  *
   7  * -------------------------------------------------------------------------*/
   8
   9 #include "PosixSource.h"
  10 #include "Rts.h"
  11 #include "Storage.h"
  12 #include "Schedule.h"
  13 #include "SchedAPI.h"
  14 #include "RtsFlags.h"
  15 #include "RtsUtils.h"
  16 #include "ParTicky.h"
  17 # if defined(PARALLEL_HASKELL)
  18 # include "ParallelRts.h"
  19 # include "GranSimRts.h"   // for GR_...
  20 # elif defined(GRAN)
  21 # include "GranSimRts.h"
  22 # endif
  23 #include "Sparks.h"
  24 #include "Trace.h"
  25
  26 #if defined(THREADED_RTS) || defined(PARALLEL_HASKELL)
  27
  28 static INLINE_ME void bump_hd (StgSparkPool *p)
  29 { p->hd++; if (p->hd == p->lim) p->hd = p->base; }
  30
  31 static INLINE_ME void bump_tl (StgSparkPool *p)
  32 { p->tl++; if (p->tl == p->lim) p->tl = p->base; }
  33
  34 /* -----------------------------------------------------------------------------
  35  *
  36  * Initialising spark pools.
  37  *
  38  * -------------------------------------------------------------------------- */
  39
  40 static void
  41 initSparkPool(StgSparkPool *pool)
  42 {
  43     pool->base = stgMallocBytes(RtsFlags.ParFlags.maxLocalSparks
  44                                 * sizeof(StgClosure *),
  45                                 "initSparkPools");
  46     pool->lim = pool->base + RtsFlags.ParFlags.maxLocalSparks;
  47     pool->hd  = pool->base;
  48     pool->tl  = pool->base;
  49 }
  50
  51 void
  52 initSparkPools( void )
  53 {
  54 #ifdef THREADED_RTS
  55     /* walk over the capabilities, allocating a spark pool for each one */
  56     nat i;
  57     for (i = 0; i < n_capabilities; i++) {
  58         initSparkPool(&capabilities[i].r.rSparks);
  59     }
  60 #else
  61     /* allocate a single spark pool */
  62     initSparkPool(&MainCapability.r.rSparks);
  63 #endif
  64 }
  65
  66 void
  67 freeSparkPool(StgSparkPool *pool) {
  68     stgFree(pool->base);
  69 }
  70
  71 /* -----------------------------------------------------------------------------
  72  *
  73  * findSpark: find a spark on the current Capability that we can fork
  74  * into a thread.
  75  *
  76  * -------------------------------------------------------------------------- */
  77
  78 StgClosure *
  79 findSpark (Capability *cap)
  80 {
  81     StgSparkPool *pool;
  82     StgClosure *spark;
  83
  84     pool = &(cap->r.rSparks);
  85     ASSERT_SPARK_POOL_INVARIANTS(pool);
  86
  87     while (pool->hd != pool->tl) {
  88         spark = *pool->hd;
  89         bump_hd(pool);
  90         if (closure_SHOULD_SPARK(spark)) {
  91 #ifdef GRAN
  92             if (RtsFlags.ParFlags.ParStats.Sparks)
  93                 DumpRawGranEvent(CURRENT_PROC, CURRENT_PROC,
  94                                  GR_STEALING, ((StgTSO *)NULL), spark,
  95                                  0, 0 /* spark_queue_len(ADVISORY_POOL) */);
  96 #endif
  97             return spark;
  98         }
  99     }
 100     // spark pool is now empty
 101     return NULL;
 102 }
 103
 104 /* -----------------------------------------------------------------------------
 105  *
 106  * Turn a spark into a real thread
 107  *
 108  * -------------------------------------------------------------------------- */
 109
 110 void
 111 createSparkThread (Capability *cap, StgClosure *p)
 112 {
 113     StgTSO *tso;
 114
 115     tso = createGenThread (cap, RtsFlags.GcFlags.initialStkSize, p);
 116     appendToRunQueue(cap,tso);
 117 }
 118
 119 /* -----------------------------------------------------------------------------
 120  *
 121  * Create a new spark
 122  *
 123  * -------------------------------------------------------------------------- */
 124
 125 #define DISCARD_NEW
 126
 127 StgInt
 128 newSpark (StgRegTable *reg, StgClosure *p)
 129 {
 130     StgSparkPool *pool = &(reg->rSparks);
 131
 132     /* I am not sure whether this is the right thing to do.
 133      * Maybe it is better to exploit the tag information
 134      * instead of throwing it away?
 135      */
 136     p = UNTAG_CLOSURE(p);
 137
 138     ASSERT_SPARK_POOL_INVARIANTS(pool);
 139
 140     if (closure_SHOULD_SPARK(p)) {
 141 #ifdef DISCARD_NEW
 142         StgClosure **new_tl;
 143         new_tl = pool->tl + 1;
 144         if (new_tl == pool->lim) { new_tl = pool->base; }
 145         if (new_tl != pool->hd) {
 146             *pool->tl = p;
 147             pool->tl = new_tl;
 148         } else if (!closure_SHOULD_SPARK(*pool->hd)) {
 149             // if the old closure is not sparkable, discard it and
 150             // keep the new one.  Otherwise, keep the old one.
 151             *pool->tl = p;
 152             bump_hd(pool);
 153         }
 154 #else  /* DISCARD OLD */
 155         *pool->tl = p;
 156         bump_tl(pool);
 157         if (pool->tl == pool->hd) { bump_hd(pool); }
 158 #endif
 159     }
 160
 161     ASSERT_SPARK_POOL_INVARIANTS(pool);
 162     return 1;
 163 }
 164
 165 /* -----------------------------------------------------------------------------
 166  * Mark all nodes pointed to by sparks in the spark queues (for GC) Does an
 167  * implicit slide i.e. after marking all sparks are at the beginning of the
 168  * spark pool and the spark pool only contains sparkable closures
 169  * -------------------------------------------------------------------------- */
 170
 171 void
 172 updateSparkQueue (Capability *cap)
 173 {
 174     StgClosure *spark, **sparkp, **to_sparkp;
 175     nat n, pruned_sparks; // stats only
 176     StgSparkPool *pool;
 177
 178     PAR_TICKY_MARK_SPARK_QUEUE_START();
 179
 180     n = 0;
 181     pruned_sparks = 0;
 182
 183     pool = &(cap->r.rSparks);
 184
 185     ASSERT_SPARK_POOL_INVARIANTS(pool);
 186
 187     sparkp = pool->hd;
 188     to_sparkp = pool->hd;
 189     while (sparkp != pool->tl) {
 190         ASSERT(*sparkp!=NULL);
 191         ASSERT(LOOKS_LIKE_CLOSURE_PTR(((StgClosure *)*sparkp)));
 192         // ToDo?: statistics gathering here (also for GUM!)
 193         spark = isAlive(*sparkp);
 194         if (spark != NULL && closure_SHOULD_SPARK(spark)) {
 195             *to_sparkp++ = spark;
 196             if (to_sparkp == pool->lim) {
 197                 to_sparkp = pool->base;
 198             }
 199             n++;
 200         } else {
 201             pruned_sparks++;
 202         }
 203         sparkp++;
 204         if (sparkp == pool->lim) {
 205             sparkp = pool->base;
 206         }
 207     }
 208     pool->tl = to_sparkp;
 209
 210     PAR_TICKY_MARK_SPARK_QUEUE_END(n);
 211
 212     debugTrace(DEBUG_sched,
 213                "updated %d sparks and pruned %d sparks",
 214                n, pruned_sparks);
 215
 216     debugTrace(DEBUG_sched,
 217                "new spark queue len=%d; (hd=%p; tl=%p)",
 218                sparkPoolSize(pool), pool->hd, pool->tl);
 219 }
 220
 221 void
 222 traverseSparkQueue (evac_fn evac, void *user, Capability *cap)
 223 {
 224     StgClosure **sparkp;
 225     StgSparkPool *pool;
 226
 227     pool = &(cap->r.rSparks);
 228     sparkp = pool->hd;
 229     while (sparkp != pool->tl) {
 230         evac(sparkp, user);
 231         sparkp++;
 232         if (sparkp == pool->lim) {
 233             sparkp = pool->base;
 234         }
 235     }
 236 }
 237
 238 #else
 239
 240 StgInt
 241 newSpark (StgRegTable *reg STG_UNUSED, StgClosure *p STG_UNUSED)
 242 {
 243     /* nothing */
 244     return 1;
 245 }
 246
 247
 248 #endif /* PARALLEL_HASKELL || THREADED_RTS */
 249
 250
 251 /* -----------------------------------------------------------------------------
 252  *
 253  * GRAN & PARALLEL_HASKELL stuff beyond here.
 254  *
 255  * -------------------------------------------------------------------------- */
 256
 257 #if defined(PARALLEL_HASKELL) || defined(GRAN)
 258
 259 static void slide_spark_pool( StgSparkPool *pool );
 260
 261 rtsBool
 262 add_to_spark_queue( StgClosure *closure, StgSparkPool *pool )
 263 {
 264   if (pool->tl == pool->lim)
 265     slide_spark_pool(pool);
 266
 267   if (closure_SHOULD_SPARK(closure) &&
 268       pool->tl < pool->lim) {
 269     *(pool->tl++) = closure;
 270
 271 #if defined(PARALLEL_HASKELL)
 272     // collect parallel global statistics (currently done together with GC stats)
 273     if (RtsFlags.ParFlags.ParStats.Global &&
 274         RtsFlags.GcFlags.giveStats > NO_GC_STATS) {
 275       // debugBelch("Creating spark for %x @ %11.2f\n", closure, usertime());
 276       globalParStats.tot_sparks_created++;
 277     }
 278 #endif
 279     return rtsTrue;
 280   } else {
 281 #if defined(PARALLEL_HASKELL)
 282     // collect parallel global statistics (currently done together with GC stats)
 283     if (RtsFlags.ParFlags.ParStats.Global &&
 284         RtsFlags.GcFlags.giveStats > NO_GC_STATS) {
 285       //debugBelch("Ignoring spark for %x @ %11.2f\n", closure, usertime());
 286       globalParStats.tot_sparks_ignored++;
 287     }
 288 #endif
 289     return rtsFalse;
 290   }
 291 }
 292
 293 static void
 294 slide_spark_pool( StgSparkPool *pool )
 295 {
 296   StgClosure **sparkp, **to_sparkp;
 297
 298   sparkp = pool->hd;
 299   to_sparkp = pool->base;
 300   while (sparkp < pool->tl) {
 301     ASSERT(to_sparkp<=sparkp);
 302     ASSERT(*sparkp!=NULL);
 303     ASSERT(LOOKS_LIKE_GHC_INFO((*sparkp)->header.info));
 304
 305     if (closure_SHOULD_SPARK(*sparkp)) {
 306       *to_sparkp++ = *sparkp++;
 307     } else {
 308       sparkp++;
 309     }
 310   }
 311   pool->hd = pool->base;
 312   pool->tl = to_sparkp;
 313 }
 314
 315 void
 316 disposeSpark(spark)
 317 StgClosure *spark;
 318 {
 319 #if !defined(THREADED_RTS)
 320   Capability *cap;
 321   StgSparkPool *pool;
 322
 323   cap = &MainRegTable;
 324   pool = &(cap->rSparks);
 325   ASSERT(pool->hd <= pool->tl && pool->tl <= pool->lim);
 326 #endif
 327   ASSERT(spark != (StgClosure *)NULL);
 328   /* Do nothing */
 329 }
 330
 331
 332 #elif defined(GRAN)
 333
 334 /*
 335    Search the spark queue of the proc in event for a spark that's worth
 336    turning into a thread
 337    (was gimme_spark in the old RTS)
 338 */
 339 void
 340 findLocalSpark (rtsEvent *event, rtsBool *found_res, rtsSparkQ *spark_res)
 341 {
 342    PEs proc = event->proc,       /* proc to search for work */
 343        creator = event->creator; /* proc that requested work */
 344    StgClosure* node;
 345    rtsBool found;
 346    rtsSparkQ spark_of_non_local_node = NULL,
 347              spark_of_non_local_node_prev = NULL,
 348              low_priority_spark = NULL,
 349              low_priority_spark_prev = NULL,
 350              spark = NULL, prev = NULL;
 351
 352    /* Choose a spark from the local spark queue */
 353    prev = (rtsSpark*)NULL;
 354    spark = pending_sparks_hds[proc];
 355    found = rtsFalse;
 356
 357    // ToDo: check this code & implement local sparking !! -- HWL
 358    while (!found && spark != (rtsSpark*)NULL)
 359      {
 360        ASSERT((prev!=(rtsSpark*)NULL || spark==pending_sparks_hds[proc]) &&
 361               (prev==(rtsSpark*)NULL || prev->next==spark) &&
 362               (spark->prev==prev));
 363        node = spark->node;
 364        if (!closure_SHOULD_SPARK(node))
 365          {
 366            IF_GRAN_DEBUG(checkSparkQ,
 367                          debugBelch("^^ pruning spark %p (node %p) in gimme_spark",
 368                                spark, node));
 369
 370            if (RtsFlags.GranFlags.GranSimStats.Sparks)
 371              DumpRawGranEvent(proc, (PEs)0, SP_PRUNED,(StgTSO*)NULL,
 372                               spark->node, spark->name, spark_queue_len(proc));
 373
 374            ASSERT(spark != (rtsSpark*)NULL);
 375            ASSERT(SparksAvail>0);
 376            --SparksAvail;
 377
 378            ASSERT(prev==(rtsSpark*)NULL || prev->next==spark);
 379            spark = delete_from_sparkq (spark, proc, rtsTrue);
 380            if (spark != (rtsSpark*)NULL)
 381              prev = spark->prev;
 382            continue;
 383          }
 384        /* -- node should eventually be sparked */
 385        else if (RtsFlags.GranFlags.PreferSparksOfLocalNodes &&
 386                !IS_LOCAL_TO(PROCS(node),CurrentProc))
 387          {
 388            barf("Local sparking not yet implemented");
 389
 390            /* Remember first low priority spark */
 391            if (spark_of_non_local_node==(rtsSpark*)NULL) {
 392              spark_of_non_local_node_prev = prev;
 393              spark_of_non_local_node = spark;
 394               }
 395
 396            if (spark->next == (rtsSpark*)NULL) {
 397              /* ASSERT(spark==SparkQueueTl);  just for testing */
 398              prev = spark_of_non_local_node_prev;
 399              spark = spark_of_non_local_node;
 400              found = rtsTrue;
 401              break;
 402            }
 403
 404 # if defined(GRAN) && defined(GRAN_CHECK)
 405            /* Should never happen; just for testing
 406            if (spark==pending_sparks_tl) {
 407              debugBelch("ReSchedule: Last spark != SparkQueueTl\n");
 408                 stg_exit(EXIT_FAILURE);
 409                 } */
 410 # endif
 411            prev = spark;
 412            spark = spark->next;
 413            ASSERT(SparksAvail>0);
 414            --SparksAvail;
 415            continue;
 416          }
 417        else if ( RtsFlags.GranFlags.DoPrioritySparking ||
 418                  (spark->gran_info >= RtsFlags.GranFlags.SparkPriority2) )
 419          {
 420            if (RtsFlags.GranFlags.DoPrioritySparking)
 421              barf("Priority sparking not yet implemented");
 422
 423            found = rtsTrue;
 424          }
 425 #if 0
 426        else /* only used if SparkPriority2 is defined */
 427          {
 428            /* ToDo: fix the code below and re-integrate it */
 429            /* Remember first low priority spark */
 430            if (low_priority_spark==(rtsSpark*)NULL) {
 431              low_priority_spark_prev = prev;
 432              low_priority_spark = spark;
 433            }
 434
 435            if (spark->next == (rtsSpark*)NULL) {
 436                 /* ASSERT(spark==spark_queue_tl);  just for testing */
 437              prev = low_priority_spark_prev;
 438              spark = low_priority_spark;
 439              found = rtsTrue;       /* take low pri spark => rc is 2  */
 440              break;
 441            }
 442
 443            /* Should never happen; just for testing
 444            if (spark==pending_sparks_tl) {
 445              debugBelch("ReSchedule: Last spark != SparkQueueTl\n");
 446                 stg_exit(EXIT_FAILURE);
 447              break;
 448            } */
 449            prev = spark;
 450            spark = spark->next;
 451
 452            IF_GRAN_DEBUG(pri,
 453                          debugBelch("++ Ignoring spark of priority %u (SparkPriority=%u); node=%p; name=%u\n",
 454                                spark->gran_info, RtsFlags.GranFlags.SparkPriority,
 455                                spark->node, spark->name);)
 456            }
 457 #endif
 458    }  /* while (spark!=NULL && !found) */
 459
 460    *spark_res = spark;
 461    *found_res = found;
 462 }
 463
 464 /*
 465   Turn the spark into a thread.
 466   In GranSim this basically means scheduling a StartThread event for the
 467   node pointed to by the spark at some point in the future.
 468   (was munch_spark in the old RTS)
 469 */
 470 rtsBool
 471 activateSpark (rtsEvent *event, rtsSparkQ spark)
 472 {
 473   PEs proc = event->proc,       /* proc to search for work */
 474       creator = event->creator; /* proc that requested work */
 475   StgTSO* tso;
 476   StgClosure* node;
 477   rtsTime spark_arrival_time;
 478
 479   /*
 480      We've found a node on PE proc requested by PE creator.
 481      If proc==creator we can turn the spark into a thread immediately;
 482      otherwise we schedule a MoveSpark event on the requesting PE
 483   */
 484
 485   /* DaH Qu' yIchen */
 486   if (proc!=creator) {
 487
 488     /* only possible if we simulate GUM style fishing */
 489     ASSERT(RtsFlags.GranFlags.Fishing);
 490
 491     /* Message packing costs for sending a Fish; qeq jabbI'ID */
 492     CurrentTime[proc] += RtsFlags.GranFlags.Costs.mpacktime;
 493
 494     if (RtsFlags.GranFlags.GranSimStats.Sparks)
 495       DumpRawGranEvent(proc, (PEs)0, SP_EXPORTED,
 496                        (StgTSO*)NULL, spark->node,
 497                        spark->name, spark_queue_len(proc));
 498
 499     /* time of the spark arrival on the remote PE */
 500     spark_arrival_time = CurrentTime[proc] + RtsFlags.GranFlags.Costs.latency;
 501
 502     new_event(creator, proc, spark_arrival_time,
 503               MoveSpark,
 504               (StgTSO*)NULL, spark->node, spark);
 505
 506     CurrentTime[proc] += RtsFlags.GranFlags.Costs.mtidytime;
 507
 508   } else { /* proc==creator i.e. turn the spark into a thread */
 509
 510     if ( RtsFlags.GranFlags.GranSimStats.Global &&
 511          spark->gran_info < RtsFlags.GranFlags.SparkPriority2 ) {
 512
 513       globalGranStats.tot_low_pri_sparks++;
 514       IF_GRAN_DEBUG(pri,
 515                     debugBelch("++ No high priority spark available; low priority (%u) spark chosen: node=%p; name=%u\n",
 516                           spark->gran_info,
 517                           spark->node, spark->name));
 518     }
 519
 520     CurrentTime[proc] += RtsFlags.GranFlags.Costs.threadcreatetime;
 521
 522     node = spark->node;
 523
 524 # if 0
 525     /* ToDo: fix the GC interface and move to StartThread handling-- HWL */
 526     if (GARBAGE COLLECTION IS NECESSARY) {
 527       /* Some kind of backoff needed here in case there's too little heap */
 528 #  if defined(GRAN_CHECK) && defined(GRAN)
 529       if (RtsFlags.GcFlags.giveStats)
 530         fprintf(RtsFlags.GcFlags.statsFile,"***** vIS Qu' chen veQ boSwI'; spark=%p, node=%p;  name=%u\n",
 531                 /* (found==2 ? "no hi pri spark" : "hi pri spark"), */
 532                 spark, node, spark->name);
 533 #  endif
 534       new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc]+1,
 535                   FindWork,
 536                   (StgTSO*)NULL, (StgClosure*)NULL, (rtsSpark*)NULL);
 537       barf("//// activateSpark: out of heap ; ToDo: call GarbageCollect()");
 538       GarbageCollect(GetRoots, rtsFalse);
 539       // HWL old: ReallyPerformThreadGC(TSO_HS+TSO_CTS_SIZE,rtsFalse);
 540       // HWL old: SAVE_Hp -= TSO_HS+TSO_CTS_SIZE;
 541       spark = NULL;
 542       return; /* was: continue; */ /* to the next event, eventually */
 543     }
 544 # endif
 545
 546     if (RtsFlags.GranFlags.GranSimStats.Sparks)
 547       DumpRawGranEvent(CurrentProc,(PEs)0,SP_USED,(StgTSO*)NULL,
 548                        spark->node, spark->name,
 549                        spark_queue_len(CurrentProc));
 550
 551     new_event(proc, proc, CurrentTime[proc],
 552               StartThread,
 553               END_TSO_QUEUE, node, spark); // (rtsSpark*)NULL);
 554
 555     procStatus[proc] = Starting;
 556   }
 557 }
 558
 559 /* -------------------------------------------------------------------------
 560    This is the main point where handling granularity information comes into
 561    play.
 562    ------------------------------------------------------------------------- */
 563
 564 #define MAX_RAND_PRI    100
 565
 566 /*
 567    Granularity info transformers.
 568    Applied to the GRAN_INFO field of a spark.
 569 */
 570 STATIC_INLINE nat  ID(nat x) { return(x); };
 571 STATIC_INLINE nat  INV(nat x) { return(-x); };
 572 STATIC_INLINE nat  IGNORE(nat x) { return (0); };
 573 STATIC_INLINE nat  RAND(nat x) { return ((random() % MAX_RAND_PRI) + 1); }
 574
 575 /* NB: size_info and par_info are currently unused (what a shame!) -- HWL */
 576 rtsSpark *
 577 newSpark(node,name,gran_info,size_info,par_info,local)
 578 StgClosure *node;
 579 nat name, gran_info, size_info, par_info, local;
 580 {
 581   nat pri;
 582   rtsSpark *newspark;
 583
 584   pri = RtsFlags.GranFlags.RandomPriorities ? RAND(gran_info) :
 585         RtsFlags.GranFlags.InversePriorities ? INV(gran_info) :
 586         RtsFlags.GranFlags.IgnorePriorities ? IGNORE(gran_info) :
 587                            ID(gran_info);
 588
 589   if ( RtsFlags.GranFlags.SparkPriority!=0 &&
 590        pri<RtsFlags.GranFlags.SparkPriority ) {
 591     IF_GRAN_DEBUG(pri,
 592       debugBelch(",, NewSpark: Ignoring spark of priority %u (SparkPriority=%u); node=%#x; name=%u\n",
 593               pri, RtsFlags.GranFlags.SparkPriority, node, name));
 594     return ((rtsSpark*)NULL);
 595   }
 596
 597   newspark = (rtsSpark*) stgMallocBytes(sizeof(rtsSpark), "NewSpark");
 598   newspark->prev = newspark->next = (rtsSpark*)NULL;
 599   newspark->node = node;
 600   newspark->name = (name==1) ? CurrentTSO->gran.sparkname : name;
 601   newspark->gran_info = pri;
 602   newspark->global = !local;      /* Check that with parAt, parAtAbs !!*/
 603
 604   if (RtsFlags.GranFlags.GranSimStats.Global) {
 605     globalGranStats.tot_sparks_created++;
 606     globalGranStats.sparks_created_on_PE[CurrentProc]++;
 607   }
 608
 609   return(newspark);
 610 }
 611
 612 void
 613 disposeSpark(spark)
 614 rtsSpark *spark;
 615 {
 616   ASSERT(spark!=NULL);
 617   stgFree(spark);
 618 }
 619
 620 void
 621 disposeSparkQ(spark)
 622 rtsSparkQ spark;
 623 {
 624   if (spark==NULL)
 625     return;
 626
 627   disposeSparkQ(spark->next);
 628
 629 # ifdef GRAN_CHECK
 630   if (SparksAvail < 0) {
 631     debugBelch("disposeSparkQ: SparksAvail<0 after disposing sparkq @ %p\n", &spark);
 632     print_spark(spark);
 633   }
 634 # endif
 635
 636   stgFree(spark);
 637 }
 638
 639 /*
 640    With PrioritySparking add_to_spark_queue performs an insert sort to keep
 641    the spark queue sorted. Otherwise the spark is just added to the end of
 642    the queue.
 643 */
 644
 645 void
 646 add_to_spark_queue(spark)
 647 rtsSpark *spark;
 648 {
 649   rtsSpark *prev = NULL, *next = NULL;
 650   nat count = 0;
 651   rtsBool found = rtsFalse;
 652
 653   if ( spark == (rtsSpark *)NULL ) {
 654     return;
 655   }
 656
 657   if (RtsFlags.GranFlags.DoPrioritySparking && (spark->gran_info != 0) ) {
 658     /* Priority sparking is enabled i.e. spark queues must be sorted */
 659
 660     for (prev = NULL, next = pending_sparks_hd, count=0;
 661          (next != NULL) &&
 662          !(found = (spark->gran_info >= next->gran_info));
 663          prev = next, next = next->next, count++)
 664      {}
 665
 666   } else {   /* 'utQo' */
 667     /* Priority sparking is disabled */
 668
 669     found = rtsFalse;   /* to add it at the end */
 670
 671   }
 672
 673   if (found) {
 674     /* next points to the first spark with a gran_info smaller than that
 675        of spark; therefore, add spark before next into the spark queue */
 676     spark->next = next;
 677     if ( next == NULL ) {
 678       pending_sparks_tl = spark;
 679     } else {
 680       next->prev = spark;
 681     }
 682     spark->prev = prev;
 683     if ( prev == NULL ) {
 684       pending_sparks_hd = spark;
 685     } else {
 686       prev->next = spark;
 687     }
 688   } else {  /* (RtsFlags.GranFlags.DoPrioritySparking && !found) || !DoPrioritySparking */
 689     /* add the spark at the end of the spark queue */
 690     spark->next = NULL;
 691     spark->prev = pending_sparks_tl;
 692     if (pending_sparks_hd == NULL)
 693       pending_sparks_hd = spark;
 694     else
 695       pending_sparks_tl->next = spark;
 696     pending_sparks_tl = spark;
 697   }
 698   ++SparksAvail;
 699
 700   /* add costs for search in priority sparking */
 701   if (RtsFlags.GranFlags.DoPrioritySparking) {
 702     CurrentTime[CurrentProc] += count * RtsFlags.GranFlags.Costs.pri_spark_overhead;
 703   }
 704
 705   IF_GRAN_DEBUG(checkSparkQ,
 706                 debugBelch("++ Spark stats after adding spark %p (node %p) to queue on PE %d",
 707                       spark, spark->node, CurrentProc);
 708                 print_sparkq_stats());
 709
 710 #  if defined(GRAN_CHECK)
 711   if (RtsFlags.GranFlags.Debug.checkSparkQ) {
 712     for (prev = NULL, next =  pending_sparks_hd;
 713          (next != NULL);
 714          prev = next, next = next->next)
 715       {}
 716     if ( (prev!=NULL) && (prev!=pending_sparks_tl) )
 717       debugBelch("SparkQ inconsistency after adding spark %p: (PE %u) pending_sparks_tl (%p) not end of queue (%p)\n",
 718               spark,CurrentProc,
 719               pending_sparks_tl, prev);
 720   }
 721 #  endif
 722
 723 #  if defined(GRAN_CHECK)
 724   /* Check if the sparkq is still sorted. Just for testing, really!  */
 725   if ( RtsFlags.GranFlags.Debug.checkSparkQ &&
 726        RtsFlags.GranFlags.Debug.pri ) {
 727     rtsBool sorted = rtsTrue;
 728     rtsSpark *prev, *next;
 729
 730     if (pending_sparks_hd == NULL ||
 731         pending_sparks_hd->next == NULL ) {
 732       /* just 1 elem => ok */
 733     } else {
 734       for (prev = pending_sparks_hd,
 735            next = pending_sparks_hd->next;
 736            (next != NULL) ;
 737            prev = next, next = next->next) {
 738         sorted = sorted &&
 739                  (prev->gran_info >= next->gran_info);
 740       }
 741     }
 742     if (!sorted) {
 743       debugBelch("ghuH: SPARKQ on PE %d is not sorted:\n",
 744               CurrentProc);
 745       print_sparkq(CurrentProc);
 746     }
 747   }
 748 #  endif
 749 }
 750
 751 nat
 752 spark_queue_len(proc)
 753 PEs proc;
 754 {
 755  rtsSpark *prev, *spark;                     /* prev only for testing !! */
 756  nat len;
 757
 758  for (len = 0, prev = NULL, spark = pending_sparks_hds[proc];
 759       spark != NULL;
 760       len++, prev = spark, spark = spark->next)
 761    {}
 762
 763 #  if defined(GRAN_CHECK)
 764   if ( RtsFlags.GranFlags.Debug.checkSparkQ )
 765     if ( (prev!=NULL) && (prev!=pending_sparks_tls[proc]) )
 766       debugBelch("ERROR in spark_queue_len: (PE %u) pending_sparks_tl (%p) not end of queue (%p)\n",
 767               proc, pending_sparks_tls[proc], prev);
 768 #  endif
 769
 770  return (len);
 771 }
 772
 773 /*
 774    Take spark out of the spark queue on PE p and nuke the spark. Adjusts
 775    hd and tl pointers of the spark queue. Returns a pointer to the next
 776    spark in the queue.
 777 */
 778 rtsSpark *
 779 delete_from_sparkq (spark, p, dispose_too)     /* unlink and dispose spark */
 780 rtsSpark *spark;
 781 PEs p;
 782 rtsBool dispose_too;
 783 {
 784   rtsSpark *new_spark;
 785
 786   if (spark==NULL)
 787     barf("delete_from_sparkq: trying to delete NULL spark\n");
 788
 789 #  if defined(GRAN_CHECK)
 790   if ( RtsFlags.GranFlags.Debug.checkSparkQ ) {
 791     debugBelch("## |%p:%p| (%p)<-spark=%p->(%p) <-(%p)\n",
 792             pending_sparks_hd, pending_sparks_tl,
 793             spark->prev, spark, spark->next,
 794             (spark->next==NULL ? 0 : spark->next->prev));
 795   }
 796 #  endif
 797
 798   if (spark->prev==NULL) {
 799     /* spark is first spark of queue => adjust hd pointer */
 800     ASSERT(pending_sparks_hds[p]==spark);
 801     pending_sparks_hds[p] = spark->next;
 802   } else {
 803     spark->prev->next = spark->next;
 804   }
 805   if (spark->next==NULL) {
 806     ASSERT(pending_sparks_tls[p]==spark);
 807     /* spark is first spark of queue => adjust tl pointer */
 808     pending_sparks_tls[p] = spark->prev;
 809   } else {
 810     spark->next->prev = spark->prev;
 811   }
 812   new_spark = spark->next;
 813
 814 #  if defined(GRAN_CHECK)
 815   if ( RtsFlags.GranFlags.Debug.checkSparkQ ) {
 816     debugBelch("## |%p:%p| (%p)<-spark=%p->(%p) <-(%p); spark=%p will be deleted NOW \n",
 817             pending_sparks_hd, pending_sparks_tl,
 818             spark->prev, spark, spark->next,
 819             (spark->next==NULL ? 0 : spark->next->prev), spark);
 820   }
 821 #  endif
 822
 823   if (dispose_too)
 824     disposeSpark(spark);
 825
 826   return new_spark;
 827 }
 828
 829 /* Mark all nodes pointed to by sparks in the spark queues (for GC) */
 830 void
 831 markSparkQueue(void)
 832 {
 833   StgClosure *MarkRoot(StgClosure *root); // prototype
 834   PEs p;
 835   rtsSpark *sp;
 836
 837   for (p=0; p<RtsFlags.GranFlags.proc; p++)
 838     for (sp=pending_sparks_hds[p]; sp!=NULL; sp=sp->next) {
 839       ASSERT(sp->node!=NULL);
 840       ASSERT(LOOKS_LIKE_GHC_INFO(sp->node->header.info));
 841       // ToDo?: statistics gathering here (also for GUM!)
 842       sp->node = (StgClosure *)MarkRoot(sp->node);
 843     }
 844
 845   IF_DEBUG(gc,
 846            debugBelch("markSparkQueue: spark statistics at start of GC:");
 847            print_sparkq_stats());
 848 }
 849
 850 void
 851 print_spark(spark)
 852 rtsSpark *spark;
 853 {
 854   char str[16];
 855
 856   if (spark==NULL) {
 857     debugBelch("Spark: NIL\n");
 858     return;
 859   } else {
 860     sprintf(str,
 861             ((spark->node==NULL) ? "______" : "%#6lx"),
 862             stgCast(StgPtr,spark->node));
 863
 864     debugBelch("Spark: Node %8s, Name %#6x, Global %5s, Creator %5x, Prev %6p, Next %6p\n",
 865             str, spark->name,
 866             ((spark->global)==rtsTrue?"True":"False"), spark->creator,
 867             spark->prev, spark->next);
 868   }
 869 }
 870
 871 void
 872 print_sparkq(proc)
 873 PEs proc;
 874 // rtsSpark *hd;
 875 {
 876   rtsSpark *x = pending_sparks_hds[proc];
 877
 878   debugBelch("Spark Queue of PE %d with root at %p:\n", proc, x);
 879   for (; x!=(rtsSpark*)NULL; x=x->next) {
 880     print_spark(x);
 881   }
 882 }
 883
 884 /*
 885    Print a statistics of all spark queues.
 886 */
 887 void
 888 print_sparkq_stats(void)
 889 {
 890   PEs p;
 891
 892   debugBelch("SparkQs: [");
 893   for (p=0; p<RtsFlags.GranFlags.proc; p++)
 894     debugBelch(", PE %d: %d", p, spark_queue_len(p));
 895   debugBelch("\n");
 896 }
 897
 898 #endif