/* --------------------------------------------------------------------------- * * (c) The GHC Team, 2000-2006 * * Sparking support for PARALLEL_HASKELL and THREADED_RTS versions of the RTS. * * -------------------------------------------------------------------------*/ #include "PosixSource.h" #include "Rts.h" #include "Storage.h" #include "Schedule.h" #include "SchedAPI.h" #include "RtsFlags.h" #include "RtsUtils.h" #include "ParTicky.h" # if defined(PARALLEL_HASKELL) # include "ParallelRts.h" # include "GranSimRts.h" // for GR_... # elif defined(GRAN) # include "GranSimRts.h" # endif #include "Sparks.h" #include "Trace.h" #if defined(THREADED_RTS) || defined(PARALLEL_HASKELL) static INLINE_ME void bump_hd (StgSparkPool *p) { p->hd++; if (p->hd == p->lim) p->hd = p->base; } static INLINE_ME void bump_tl (StgSparkPool *p) { p->tl++; if (p->tl == p->lim) p->tl = p->base; } /* ----------------------------------------------------------------------------- * * Initialising spark pools. * * -------------------------------------------------------------------------- */ static void initSparkPool(StgSparkPool *pool) { pool->base = stgMallocBytes(RtsFlags.ParFlags.maxLocalSparks * sizeof(StgClosure *), "initSparkPools"); pool->lim = pool->base + RtsFlags.ParFlags.maxLocalSparks; pool->hd = pool->base; pool->tl = pool->base; } void initSparkPools( void ) { #ifdef THREADED_RTS /* walk over the capabilities, allocating a spark pool for each one */ nat i; for (i = 0; i < n_capabilities; i++) { initSparkPool(&capabilities[i].r.rSparks); } #else /* allocate a single spark pool */ initSparkPool(&MainCapability.r.rSparks); #endif } /* ----------------------------------------------------------------------------- * * findSpark: find a spark on the current Capability that we can fork * into a thread. * * -------------------------------------------------------------------------- */ StgClosure * findSpark (Capability *cap) { StgSparkPool *pool; StgClosure *spark; pool = &(cap->r.rSparks); ASSERT_SPARK_POOL_INVARIANTS(pool); while (pool->hd != pool->tl) { spark = *pool->hd; bump_hd(pool); if (closure_SHOULD_SPARK(spark)) { #ifdef GRAN if (RtsFlags.ParFlags.ParStats.Sparks) DumpRawGranEvent(CURRENT_PROC, CURRENT_PROC, GR_STEALING, ((StgTSO *)NULL), spark, 0, 0 /* spark_queue_len(ADVISORY_POOL) */); #endif return spark; } } // spark pool is now empty return NULL; } /* ----------------------------------------------------------------------------- * Mark all nodes pointed to by sparks in the spark queues (for GC) Does an * implicit slide i.e. after marking all sparks are at the beginning of the * spark pool and the spark pool only contains sparkable closures * -------------------------------------------------------------------------- */ void markSparkQueue (evac_fn evac) { StgClosure **sparkp, **to_sparkp; nat i, n, pruned_sparks; // stats only StgSparkPool *pool; Capability *cap; PAR_TICKY_MARK_SPARK_QUEUE_START(); n = 0; pruned_sparks = 0; for (i = 0; i < n_capabilities; i++) { cap = &capabilities[i]; pool = &(cap->r.rSparks); ASSERT_SPARK_POOL_INVARIANTS(pool); #if defined(PARALLEL_HASKELL) // stats only n = 0; pruned_sparks = 0; #endif sparkp = pool->hd; to_sparkp = pool->hd; while (sparkp != pool->tl) { ASSERT(*sparkp!=NULL); ASSERT(LOOKS_LIKE_CLOSURE_PTR(((StgClosure *)*sparkp))); // ToDo?: statistics gathering here (also for GUM!) if (closure_SHOULD_SPARK(*sparkp)) { evac(sparkp); *to_sparkp++ = *sparkp; if (to_sparkp == pool->lim) { to_sparkp = pool->base; } n++; } else { pruned_sparks++; } sparkp++; if (sparkp == pool->lim) { sparkp = pool->base; } } pool->tl = to_sparkp; PAR_TICKY_MARK_SPARK_QUEUE_END(n); #if defined(PARALLEL_HASKELL) debugTrace(DEBUG_sched, "marked %d sparks and pruned %d sparks on [%x]", n, pruned_sparks, mytid); #else debugTrace(DEBUG_sched, "marked %d sparks and pruned %d sparks", n, pruned_sparks); #endif debugTrace(DEBUG_sched, "new spark queue len=%d; (hd=%p; tl=%p)\n", sparkPoolSize(pool), pool->hd, pool->tl); } } /* ----------------------------------------------------------------------------- * * Turn a spark into a real thread * * -------------------------------------------------------------------------- */ void createSparkThread (Capability *cap, StgClosure *p) { StgTSO *tso; tso = createGenThread (cap, RtsFlags.GcFlags.initialStkSize, p); appendToRunQueue(cap,tso); } /* ----------------------------------------------------------------------------- * * Create a new spark * * -------------------------------------------------------------------------- */ #define DISCARD_NEW StgInt newSpark (StgRegTable *reg, StgClosure *p) { StgSparkPool *pool = &(reg->rSparks); ASSERT_SPARK_POOL_INVARIANTS(pool); if (closure_SHOULD_SPARK(p)) { #ifdef DISCARD_NEW StgClosure **new_tl; new_tl = pool->tl + 1; if (new_tl == pool->lim) { new_tl = pool->base; } if (new_tl != pool->hd) { *pool->tl = p; pool->tl = new_tl; } else if (!closure_SHOULD_SPARK(*pool->hd)) { // if the old closure is not sparkable, discard it and // keep the new one. Otherwise, keep the old one. *pool->tl = p; bump_hd(pool); } #else /* DISCARD OLD */ *pool->tl = p; bump_tl(pool); if (pool->tl == pool->hd) { bump_hd(pool); } #endif } ASSERT_SPARK_POOL_INVARIANTS(pool); return 1; } #else StgInt newSpark (StgRegTable *reg STG_UNUSED, StgClosure *p STG_UNUSED) { /* nothing */ return 1; } #endif /* PARALLEL_HASKELL || THREADED_RTS */ /* ----------------------------------------------------------------------------- * * GRAN & PARALLEL_HASKELL stuff beyond here. * * -------------------------------------------------------------------------- */ #if defined(PARALLEL_HASKELL) || defined(GRAN) static void slide_spark_pool( StgSparkPool *pool ); rtsBool add_to_spark_queue( StgClosure *closure, StgSparkPool *pool ) { if (pool->tl == pool->lim) slide_spark_pool(pool); if (closure_SHOULD_SPARK(closure) && pool->tl < pool->lim) { *(pool->tl++) = closure; #if defined(PARALLEL_HASKELL) // collect parallel global statistics (currently done together with GC stats) if (RtsFlags.ParFlags.ParStats.Global && RtsFlags.GcFlags.giveStats > NO_GC_STATS) { // debugBelch("Creating spark for %x @ %11.2f\n", closure, usertime()); globalParStats.tot_sparks_created++; } #endif return rtsTrue; } else { #if defined(PARALLEL_HASKELL) // collect parallel global statistics (currently done together with GC stats) if (RtsFlags.ParFlags.ParStats.Global && RtsFlags.GcFlags.giveStats > NO_GC_STATS) { //debugBelch("Ignoring spark for %x @ %11.2f\n", closure, usertime()); globalParStats.tot_sparks_ignored++; } #endif return rtsFalse; } } static void slide_spark_pool( StgSparkPool *pool ) { StgClosure **sparkp, **to_sparkp; sparkp = pool->hd; to_sparkp = pool->base; while (sparkp < pool->tl) { ASSERT(to_sparkp<=sparkp); ASSERT(*sparkp!=NULL); ASSERT(LOOKS_LIKE_GHC_INFO((*sparkp)->header.info)); if (closure_SHOULD_SPARK(*sparkp)) { *to_sparkp++ = *sparkp++; } else { sparkp++; } } pool->hd = pool->base; pool->tl = to_sparkp; } void disposeSpark(spark) StgClosure *spark; { #if !defined(THREADED_RTS) Capability *cap; StgSparkPool *pool; cap = &MainRegTable; pool = &(cap->rSparks); ASSERT(pool->hd <= pool->tl && pool->tl <= pool->lim); #endif ASSERT(spark != (StgClosure *)NULL); /* Do nothing */ } #elif defined(GRAN) /* Search the spark queue of the proc in event for a spark that's worth turning into a thread (was gimme_spark in the old RTS) */ void findLocalSpark (rtsEvent *event, rtsBool *found_res, rtsSparkQ *spark_res) { PEs proc = event->proc, /* proc to search for work */ creator = event->creator; /* proc that requested work */ StgClosure* node; rtsBool found; rtsSparkQ spark_of_non_local_node = NULL, spark_of_non_local_node_prev = NULL, low_priority_spark = NULL, low_priority_spark_prev = NULL, spark = NULL, prev = NULL; /* Choose a spark from the local spark queue */ prev = (rtsSpark*)NULL; spark = pending_sparks_hds[proc]; found = rtsFalse; // ToDo: check this code & implement local sparking !! -- HWL while (!found && spark != (rtsSpark*)NULL) { ASSERT((prev!=(rtsSpark*)NULL || spark==pending_sparks_hds[proc]) && (prev==(rtsSpark*)NULL || prev->next==spark) && (spark->prev==prev)); node = spark->node; if (!closure_SHOULD_SPARK(node)) { IF_GRAN_DEBUG(checkSparkQ, debugBelch("^^ pruning spark %p (node %p) in gimme_spark", spark, node)); if (RtsFlags.GranFlags.GranSimStats.Sparks) DumpRawGranEvent(proc, (PEs)0, SP_PRUNED,(StgTSO*)NULL, spark->node, spark->name, spark_queue_len(proc)); ASSERT(spark != (rtsSpark*)NULL); ASSERT(SparksAvail>0); --SparksAvail; ASSERT(prev==(rtsSpark*)NULL || prev->next==spark); spark = delete_from_sparkq (spark, proc, rtsTrue); if (spark != (rtsSpark*)NULL) prev = spark->prev; continue; } /* -- node should eventually be sparked */ else if (RtsFlags.GranFlags.PreferSparksOfLocalNodes && !IS_LOCAL_TO(PROCS(node),CurrentProc)) { barf("Local sparking not yet implemented"); /* Remember first low priority spark */ if (spark_of_non_local_node==(rtsSpark*)NULL) { spark_of_non_local_node_prev = prev; spark_of_non_local_node = spark; } if (spark->next == (rtsSpark*)NULL) { /* ASSERT(spark==SparkQueueTl); just for testing */ prev = spark_of_non_local_node_prev; spark = spark_of_non_local_node; found = rtsTrue; break; } # if defined(GRAN) && defined(GRAN_CHECK) /* Should never happen; just for testing if (spark==pending_sparks_tl) { debugBelch("ReSchedule: Last spark != SparkQueueTl\n"); stg_exit(EXIT_FAILURE); } */ # endif prev = spark; spark = spark->next; ASSERT(SparksAvail>0); --SparksAvail; continue; } else if ( RtsFlags.GranFlags.DoPrioritySparking || (spark->gran_info >= RtsFlags.GranFlags.SparkPriority2) ) { if (RtsFlags.GranFlags.DoPrioritySparking) barf("Priority sparking not yet implemented"); found = rtsTrue; } #if 0 else /* only used if SparkPriority2 is defined */ { /* ToDo: fix the code below and re-integrate it */ /* Remember first low priority spark */ if (low_priority_spark==(rtsSpark*)NULL) { low_priority_spark_prev = prev; low_priority_spark = spark; } if (spark->next == (rtsSpark*)NULL) { /* ASSERT(spark==spark_queue_tl); just for testing */ prev = low_priority_spark_prev; spark = low_priority_spark; found = rtsTrue; /* take low pri spark => rc is 2 */ break; } /* Should never happen; just for testing if (spark==pending_sparks_tl) { debugBelch("ReSchedule: Last spark != SparkQueueTl\n"); stg_exit(EXIT_FAILURE); break; } */ prev = spark; spark = spark->next; IF_GRAN_DEBUG(pri, debugBelch("++ Ignoring spark of priority %u (SparkPriority=%u); node=%p; name=%u\n", spark->gran_info, RtsFlags.GranFlags.SparkPriority, spark->node, spark->name);) } #endif } /* while (spark!=NULL && !found) */ *spark_res = spark; *found_res = found; } /* Turn the spark into a thread. In GranSim this basically means scheduling a StartThread event for the node pointed to by the spark at some point in the future. (was munch_spark in the old RTS) */ rtsBool activateSpark (rtsEvent *event, rtsSparkQ spark) { PEs proc = event->proc, /* proc to search for work */ creator = event->creator; /* proc that requested work */ StgTSO* tso; StgClosure* node; rtsTime spark_arrival_time; /* We've found a node on PE proc requested by PE creator. If proc==creator we can turn the spark into a thread immediately; otherwise we schedule a MoveSpark event on the requesting PE */ /* DaH Qu' yIchen */ if (proc!=creator) { /* only possible if we simulate GUM style fishing */ ASSERT(RtsFlags.GranFlags.Fishing); /* Message packing costs for sending a Fish; qeq jabbI'ID */ CurrentTime[proc] += RtsFlags.GranFlags.Costs.mpacktime; if (RtsFlags.GranFlags.GranSimStats.Sparks) DumpRawGranEvent(proc, (PEs)0, SP_EXPORTED, (StgTSO*)NULL, spark->node, spark->name, spark_queue_len(proc)); /* time of the spark arrival on the remote PE */ spark_arrival_time = CurrentTime[proc] + RtsFlags.GranFlags.Costs.latency; new_event(creator, proc, spark_arrival_time, MoveSpark, (StgTSO*)NULL, spark->node, spark); CurrentTime[proc] += RtsFlags.GranFlags.Costs.mtidytime; } else { /* proc==creator i.e. turn the spark into a thread */ if ( RtsFlags.GranFlags.GranSimStats.Global && spark->gran_info < RtsFlags.GranFlags.SparkPriority2 ) { globalGranStats.tot_low_pri_sparks++; IF_GRAN_DEBUG(pri, debugBelch("++ No high priority spark available; low priority (%u) spark chosen: node=%p; name=%u\n", spark->gran_info, spark->node, spark->name)); } CurrentTime[proc] += RtsFlags.GranFlags.Costs.threadcreatetime; node = spark->node; # if 0 /* ToDo: fix the GC interface and move to StartThread handling-- HWL */ if (GARBAGE COLLECTION IS NECESSARY) { /* Some kind of backoff needed here in case there's too little heap */ # if defined(GRAN_CHECK) && defined(GRAN) if (RtsFlags.GcFlags.giveStats) fprintf(RtsFlags.GcFlags.statsFile,"***** vIS Qu' chen veQ boSwI'; spark=%p, node=%p; name=%u\n", /* (found==2 ? "no hi pri spark" : "hi pri spark"), */ spark, node, spark->name); # endif new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc]+1, FindWork, (StgTSO*)NULL, (StgClosure*)NULL, (rtsSpark*)NULL); barf("//// activateSpark: out of heap ; ToDo: call GarbageCollect()"); GarbageCollect(GetRoots, rtsFalse); // HWL old: ReallyPerformThreadGC(TSO_HS+TSO_CTS_SIZE,rtsFalse); // HWL old: SAVE_Hp -= TSO_HS+TSO_CTS_SIZE; spark = NULL; return; /* was: continue; */ /* to the next event, eventually */ } # endif if (RtsFlags.GranFlags.GranSimStats.Sparks) DumpRawGranEvent(CurrentProc,(PEs)0,SP_USED,(StgTSO*)NULL, spark->node, spark->name, spark_queue_len(CurrentProc)); new_event(proc, proc, CurrentTime[proc], StartThread, END_TSO_QUEUE, node, spark); // (rtsSpark*)NULL); procStatus[proc] = Starting; } } /* ------------------------------------------------------------------------- This is the main point where handling granularity information comes into play. ------------------------------------------------------------------------- */ #define MAX_RAND_PRI 100 /* Granularity info transformers. Applied to the GRAN_INFO field of a spark. */ STATIC_INLINE nat ID(nat x) { return(x); }; STATIC_INLINE nat INV(nat x) { return(-x); }; STATIC_INLINE nat IGNORE(nat x) { return (0); }; STATIC_INLINE nat RAND(nat x) { return ((random() % MAX_RAND_PRI) + 1); } /* NB: size_info and par_info are currently unused (what a shame!) -- HWL */ rtsSpark * newSpark(node,name,gran_info,size_info,par_info,local) StgClosure *node; nat name, gran_info, size_info, par_info, local; { nat pri; rtsSpark *newspark; pri = RtsFlags.GranFlags.RandomPriorities ? RAND(gran_info) : RtsFlags.GranFlags.InversePriorities ? INV(gran_info) : RtsFlags.GranFlags.IgnorePriorities ? IGNORE(gran_info) : ID(gran_info); if ( RtsFlags.GranFlags.SparkPriority!=0 && priprev = newspark->next = (rtsSpark*)NULL; newspark->node = node; newspark->name = (name==1) ? CurrentTSO->gran.sparkname : name; newspark->gran_info = pri; newspark->global = !local; /* Check that with parAt, parAtAbs !!*/ if (RtsFlags.GranFlags.GranSimStats.Global) { globalGranStats.tot_sparks_created++; globalGranStats.sparks_created_on_PE[CurrentProc]++; } return(newspark); } void disposeSpark(spark) rtsSpark *spark; { ASSERT(spark!=NULL); stgFree(spark); } void disposeSparkQ(spark) rtsSparkQ spark; { if (spark==NULL) return; disposeSparkQ(spark->next); # ifdef GRAN_CHECK if (SparksAvail < 0) { debugBelch("disposeSparkQ: SparksAvail<0 after disposing sparkq @ %p\n", &spark); print_spark(spark); } # endif stgFree(spark); } /* With PrioritySparking add_to_spark_queue performs an insert sort to keep the spark queue sorted. Otherwise the spark is just added to the end of the queue. */ void add_to_spark_queue(spark) rtsSpark *spark; { rtsSpark *prev = NULL, *next = NULL; nat count = 0; rtsBool found = rtsFalse; if ( spark == (rtsSpark *)NULL ) { return; } if (RtsFlags.GranFlags.DoPrioritySparking && (spark->gran_info != 0) ) { /* Priority sparking is enabled i.e. spark queues must be sorted */ for (prev = NULL, next = pending_sparks_hd, count=0; (next != NULL) && !(found = (spark->gran_info >= next->gran_info)); prev = next, next = next->next, count++) {} } else { /* 'utQo' */ /* Priority sparking is disabled */ found = rtsFalse; /* to add it at the end */ } if (found) { /* next points to the first spark with a gran_info smaller than that of spark; therefore, add spark before next into the spark queue */ spark->next = next; if ( next == NULL ) { pending_sparks_tl = spark; } else { next->prev = spark; } spark->prev = prev; if ( prev == NULL ) { pending_sparks_hd = spark; } else { prev->next = spark; } } else { /* (RtsFlags.GranFlags.DoPrioritySparking && !found) || !DoPrioritySparking */ /* add the spark at the end of the spark queue */ spark->next = NULL; spark->prev = pending_sparks_tl; if (pending_sparks_hd == NULL) pending_sparks_hd = spark; else pending_sparks_tl->next = spark; pending_sparks_tl = spark; } ++SparksAvail; /* add costs for search in priority sparking */ if (RtsFlags.GranFlags.DoPrioritySparking) { CurrentTime[CurrentProc] += count * RtsFlags.GranFlags.Costs.pri_spark_overhead; } IF_GRAN_DEBUG(checkSparkQ, debugBelch("++ Spark stats after adding spark %p (node %p) to queue on PE %d", spark, spark->node, CurrentProc); print_sparkq_stats()); # if defined(GRAN_CHECK) if (RtsFlags.GranFlags.Debug.checkSparkQ) { for (prev = NULL, next = pending_sparks_hd; (next != NULL); prev = next, next = next->next) {} if ( (prev!=NULL) && (prev!=pending_sparks_tl) ) debugBelch("SparkQ inconsistency after adding spark %p: (PE %u) pending_sparks_tl (%p) not end of queue (%p)\n", spark,CurrentProc, pending_sparks_tl, prev); } # endif # if defined(GRAN_CHECK) /* Check if the sparkq is still sorted. Just for testing, really! */ if ( RtsFlags.GranFlags.Debug.checkSparkQ && RtsFlags.GranFlags.Debug.pri ) { rtsBool sorted = rtsTrue; rtsSpark *prev, *next; if (pending_sparks_hd == NULL || pending_sparks_hd->next == NULL ) { /* just 1 elem => ok */ } else { for (prev = pending_sparks_hd, next = pending_sparks_hd->next; (next != NULL) ; prev = next, next = next->next) { sorted = sorted && (prev->gran_info >= next->gran_info); } } if (!sorted) { debugBelch("ghuH: SPARKQ on PE %d is not sorted:\n", CurrentProc); print_sparkq(CurrentProc); } } # endif } nat spark_queue_len(proc) PEs proc; { rtsSpark *prev, *spark; /* prev only for testing !! */ nat len; for (len = 0, prev = NULL, spark = pending_sparks_hds[proc]; spark != NULL; len++, prev = spark, spark = spark->next) {} # if defined(GRAN_CHECK) if ( RtsFlags.GranFlags.Debug.checkSparkQ ) if ( (prev!=NULL) && (prev!=pending_sparks_tls[proc]) ) debugBelch("ERROR in spark_queue_len: (PE %u) pending_sparks_tl (%p) not end of queue (%p)\n", proc, pending_sparks_tls[proc], prev); # endif return (len); } /* Take spark out of the spark queue on PE p and nuke the spark. Adjusts hd and tl pointers of the spark queue. Returns a pointer to the next spark in the queue. */ rtsSpark * delete_from_sparkq (spark, p, dispose_too) /* unlink and dispose spark */ rtsSpark *spark; PEs p; rtsBool dispose_too; { rtsSpark *new_spark; if (spark==NULL) barf("delete_from_sparkq: trying to delete NULL spark\n"); # if defined(GRAN_CHECK) if ( RtsFlags.GranFlags.Debug.checkSparkQ ) { debugBelch("## |%p:%p| (%p)<-spark=%p->(%p) <-(%p)\n", pending_sparks_hd, pending_sparks_tl, spark->prev, spark, spark->next, (spark->next==NULL ? 0 : spark->next->prev)); } # endif if (spark->prev==NULL) { /* spark is first spark of queue => adjust hd pointer */ ASSERT(pending_sparks_hds[p]==spark); pending_sparks_hds[p] = spark->next; } else { spark->prev->next = spark->next; } if (spark->next==NULL) { ASSERT(pending_sparks_tls[p]==spark); /* spark is first spark of queue => adjust tl pointer */ pending_sparks_tls[p] = spark->prev; } else { spark->next->prev = spark->prev; } new_spark = spark->next; # if defined(GRAN_CHECK) if ( RtsFlags.GranFlags.Debug.checkSparkQ ) { debugBelch("## |%p:%p| (%p)<-spark=%p->(%p) <-(%p); spark=%p will be deleted NOW \n", pending_sparks_hd, pending_sparks_tl, spark->prev, spark, spark->next, (spark->next==NULL ? 0 : spark->next->prev), spark); } # endif if (dispose_too) disposeSpark(spark); return new_spark; } /* Mark all nodes pointed to by sparks in the spark queues (for GC) */ void markSparkQueue(void) { StgClosure *MarkRoot(StgClosure *root); // prototype PEs p; rtsSpark *sp; for (p=0; pnext) { ASSERT(sp->node!=NULL); ASSERT(LOOKS_LIKE_GHC_INFO(sp->node->header.info)); // ToDo?: statistics gathering here (also for GUM!) sp->node = (StgClosure *)MarkRoot(sp->node); } IF_DEBUG(gc, debugBelch("markSparkQueue: spark statistics at start of GC:"); print_sparkq_stats()); } void print_spark(spark) rtsSpark *spark; { char str[16]; if (spark==NULL) { debugBelch("Spark: NIL\n"); return; } else { sprintf(str, ((spark->node==NULL) ? "______" : "%#6lx"), stgCast(StgPtr,spark->node)); debugBelch("Spark: Node %8s, Name %#6x, Global %5s, Creator %5x, Prev %6p, Next %6p\n", str, spark->name, ((spark->global)==rtsTrue?"True":"False"), spark->creator, spark->prev, spark->next); } } void print_sparkq(proc) PEs proc; // rtsSpark *hd; { rtsSpark *x = pending_sparks_hds[proc]; debugBelch("Spark Queue of PE %d with root at %p:\n", proc, x); for (; x!=(rtsSpark*)NULL; x=x->next) { print_spark(x); } } /* Print a statistics of all spark queues. */ void print_sparkq_stats(void) { PEs p; debugBelch("SparkQs: ["); for (p=0; p