X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FSparks.c;h=9e4492ac1925c66b4fe942d8a6480671200d4aac;hb=2b398b2215fd5238e222bcb3013aa41d7b631cfa;hp=360ea41a052f54e8cea28bbdcc6711dd20161ca5;hpb=99df892cc9620fcc92747b79bba75dad8a1d295c;p=ghc-hetmet.git

diff --git a/rts/Sparks.c b/rts/Sparks.c
index 360ea41..9e4492a 100644
--- a/rts/Sparks.c
+++ b/rts/Sparks.c
@@ -44,6 +44,7 @@
 #include "RtsUtils.h"
 #include "ParTicky.h"
 #include "Trace.h"
+#include "Prelude.h"
 
 #include "SMP.h" // for cas
 
@@ -201,11 +202,15 @@ steal(SparkPool *deque)
   StgClosurePtr stolen;
   StgWord b,t; 
 
-  ASSERT_SPARK_POOL_INVARIANTS(deque); 
+// Can't do this on someone else's spark pool:
+// ASSERT_SPARK_POOL_INVARIANTS(deque); 
 
   b = deque->bottom;
   t = deque->top;
-  if (b - t <= 0 ) { 
+
+  // NB. b and t are unsigned; we need a signed value for the test
+  // below.
+  if ((long)b - (long)t <= 0 ) { 
     return NULL; /* already looks empty, abort */
   }
 
@@ -221,14 +226,17 @@ steal(SparkPool *deque)
       return NULL;
   }  /* else: OK, top has been incremented by the cas call */
 
-  ASSERT_SPARK_POOL_INVARIANTS(deque); 
+// Can't do this on someone else's spark pool:
+// ASSERT_SPARK_POOL_INVARIANTS(deque); 
+
   /* return stolen element */
   return stolen;
 }
 
 StgClosure *
-tryStealSpark (SparkPool *pool)
+tryStealSpark (Capability *cap)
 {
+  SparkPool *pool = cap->sparks;
   StgClosure *stolen;
 
   do { 
@@ -253,7 +261,7 @@ looksEmpty(SparkPool* deque)
   StgWord t = deque->top;
   StgWord b = deque->bottom;
   /* try to prefer false negatives by reading top first */
-  return (b - t <= 0);
+  return ((long)b - (long)t <= 0);
   /* => array is *never* completely filled, always 1 place free! */
 }
 
@@ -264,13 +272,13 @@ looksEmpty(SparkPool* deque)
  * -------------------------------------------------------------------------- */
 
 void
-createSparkThread (Capability *cap, StgClosure *p)
+createSparkThread (Capability *cap)
 {
     StgTSO *tso;
 
-    tso = createGenThread (cap, RtsFlags.GcFlags.initialStkSize, p);
+    tso = createIOThread (cap, RtsFlags.GcFlags.initialStkSize, 
+                          &base_GHCziConc_runSparks_closure);
     appendToRunQueue(cap,tso);
-    cap->sparks_converted++;
 }
 
 /* -----------------------------------------------------------------------------
@@ -298,7 +306,10 @@ pushBottom (SparkPool* deque, StgClosurePtr elem)
      This is why we do not just call empty(deque) here.
   */
   t = deque->topBound;
-  if ( b - t >= sz ) { /* nota bene: sz == deque->size - 1, thus ">=" */
+  if ( (StgInt)b - (StgInt)t >= (StgInt)sz ) { 
+    /* NB. 1. sz == deque->size - 1, thus ">="
+           2. signed comparison, it is possible that t > b
+    */
     /* could be full, check the real top value in this case */
     t = deque->top;
     deque->topBound = t;
@@ -371,13 +382,14 @@ newSpark (StgRegTable *reg, StgClosure *p)
  * the spark pool only contains sparkable closures.
  * -------------------------------------------------------------------------- */
 
-static void
-pruneSparkQueue (Capability *cap)
+void
+pruneSparkQueue (evac_fn evac, void *user, Capability *cap)
 { 
     SparkPool *pool;
-    StgClosurePtr spark, *elements;
+    StgClosurePtr spark, tmp, *elements;
     nat n, pruned_sparks; // stats only
     StgWord botInd,oldBotInd,currInd; // indices in array (always < size)
+    const StgInfoTable *info;
     
     PAR_TICKY_MARK_SPARK_QUEUE_START();
     
@@ -386,6 +398,19 @@ pruneSparkQueue (Capability *cap)
     
     pool = cap->sparks;
     
+    // it is possible that top > bottom, indicating an empty pool.  We
+    // fix that here; this is only necessary because the loop below
+    // assumes it.
+    if (pool->top > pool->bottom)
+        pool->top = pool->bottom;
+
+    // Take this opportunity to reset top/bottom modulo the size of
+    // the array, to avoid overflow.  This is only possible because no
+    // stealing is happening during GC.
+    pool->bottom  -= pool->top & ~pool->moduloSize;
+    pool->top     &= pool->moduloSize;
+    pool->topBound = pool->top;
+
     debugTrace(DEBUG_sched,
                "markSparkQueue: current spark queue len=%d; (hd=%ld; tl=%ld)",
                sparkPoolSize(pool), pool->bottom, pool->top);
@@ -440,14 +465,31 @@ pruneSparkQueue (Capability *cap)
 	 botInd, otherwise move on */
       spark = elements[currInd];
 
-      /* if valuable work: shift inside the pool */
-      if ( closure_SHOULD_SPARK(spark) ) {
-	elements[botInd] = spark; // keep entry (new address)
-	botInd++;
-	n++;
-      } else { 
-	pruned_sparks++; // discard spark
-        cap->sparks_pruned++;
+      // We have to be careful here: in the parallel GC, another
+      // thread might evacuate this closure while we're looking at it,
+      // so grab the info pointer just once.
+      info = spark->header.info;
+      if (IS_FORWARDING_PTR(info)) {
+          tmp = (StgClosure*)UN_FORWARDING_PTR(info);
+          /* if valuable work: shift inside the pool */
+          if (closure_SHOULD_SPARK(tmp)) {
+              elements[botInd] = tmp; // keep entry (new address)
+              botInd++;
+              n++;
+          } else {
+              pruned_sparks++; // discard spark
+              cap->sparks_pruned++;
+          }
+      } else {
+          if (!(closure_flags[INFO_PTR_TO_STRUCT(info)->type] & _NS)) {
+              elements[botInd] = spark; // keep entry (new address)
+              evac (user, &elements[botInd]);
+              botInd++;
+              n++;
+          } else {
+              pruned_sparks++; // discard spark
+              cap->sparks_pruned++;
+          }
       }
       currInd++;
 
@@ -477,15 +519,6 @@ pruneSparkQueue (Capability *cap)
     ASSERT_SPARK_POOL_INVARIANTS(pool);
 }
 
-void
-pruneSparkQueues (void)
-{
-    nat i;
-    for (i = 0; i < n_capabilities; i++) {
-        pruneSparkQueue(&capabilities[i]);
-    }
-}
-
 /* GC for the spark pool, called inside Capability.c for all
    capabilities in turn. Blindly "evac"s complete spark pool. */
 void