*
* ---------------------------------------------------------------------------*/
-// #include "PosixSource.h"
+#include "PosixSource.h"
#include "Rts.h"
-#include "RtsFlags.h"
+#include "HsFFI.h"
+
+#include "Storage.h"
#include "RtsUtils.h"
#include "Apply.h"
-#include "OSThreads.h"
-#include "LdvProfile.h"
#include "Updates.h"
#include "Stats.h"
#include "Schedule.h"
#include "Sanity.h"
#include "BlockAlloc.h"
-#include "MBlock.h"
#include "ProfHeap.h"
-#include "SchedAPI.h"
#include "Weak.h"
#include "Prelude.h"
-#include "ParTicky.h" // ToDo: move into Rts.h
#include "RtsSignals.h"
#include "STM.h"
-#include "HsFFI.h"
-#include "Linker.h"
#if defined(RTS_GTK_FRONTPANEL)
#include "FrontPanel.h"
#endif
#include "Trace.h"
#include "RetainerProfile.h"
+#include "LdvProfile.h"
#include "RaiseAsync.h"
-#include "Sparks.h"
#include "Papi.h"
+#include "Stable.h"
#include "GC.h"
#include "GCThread.h"
+#include "GCTDecl.h"
#include "Compact.h"
#include "Evac.h"
#include "Scav.h"
#include "GCUtils.h"
+#include "MarkStack.h"
#include "MarkWeak.h"
#include "Sparks.h"
+#include "Sweep.h"
#include <string.h> // for memset()
#include <unistd.h>
/* Data used for allocation area sizing.
*/
-static lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC
+static lnat g0_pcnt_kept = 30; // percentage of g0 live at last minor GC
/* Mut-list stats */
#ifdef DEBUG
/* Thread-local data for each GC thread
*/
gc_thread **gc_threads = NULL;
-// gc_thread *gct = NULL; // this thread's gct TODO: make thread-local
+
+#if !defined(THREADED_RTS)
+StgWord8 the_gc_thread[sizeof(gc_thread) + 64 * sizeof(gen_workspace)];
+#endif
// Number of threads running in *this* GC. Affects how many
// step->todos[] lists we have to look in to find work.
// For stats:
long copied; // *words* copied & scavenged during this GC
-#ifdef THREADED_RTS
-SpinLock recordMutableGen_sync;
-#endif
+rtsBool work_stealing;
+
+DECLARE_GCT
/* -----------------------------------------------------------------------------
Static function declarations
static void mark_root (void *user, StgClosure **root);
static void zero_static_object_list (StgClosure* first_static);
static nat initialise_N (rtsBool force_major_gc);
-static void alloc_gc_threads (void);
-static void init_collected_gen (nat g, nat threads);
-static void init_uncollected_gen (nat g, nat threads);
+static void prepare_collected_gen (generation *gen);
+static void prepare_uncollected_gen (generation *gen);
static void init_gc_thread (gc_thread *t);
-static void update_task_list (void);
static void resize_generations (void);
static void resize_nursery (void);
static void start_gc_threads (void);
-static void gc_thread_work (void);
-static nat inc_running (void);
-static nat dec_running (void);
-static void wakeup_gc_threads (nat n_threads);
-static void shutdown_gc_threads (nat n_threads);
+static void scavenge_until_all_done (void);
+static StgWord inc_running (void);
+static StgWord dec_running (void);
+static void wakeup_gc_threads (nat me);
+static void shutdown_gc_threads (nat me);
+static void collect_gct_blocks (void);
#if 0 && defined(DEBUG)
static void gcCAFs (void);
#endif
/* -----------------------------------------------------------------------------
- The mark bitmap & stack.
+ The mark stack.
-------------------------------------------------------------------------- */
-#define MARK_STACK_BLOCKS 4
-
-bdescr *mark_stack_bdescr;
-StgPtr *mark_stack;
-StgPtr *mark_sp;
-StgPtr *mark_splim;
-
-// Flag and pointers used for falling back to a linear scan when the
-// mark stack overflows.
-rtsBool mark_stack_overflowed;
-bdescr *oldgen_scan_bd;
-StgPtr oldgen_scan;
+bdescr *mark_stack_top_bd; // topmost block in the mark stack
+bdescr *mark_stack_bd; // current block in the mark stack
+StgPtr mark_sp; // pointer to the next unallocated mark stack entry
/* -----------------------------------------------------------------------------
GarbageCollect: the main entry point to the garbage collector.
-------------------------------------------------------------------------- */
void
-GarbageCollect ( rtsBool force_major_gc )
+GarbageCollect (rtsBool force_major_gc,
+ nat gc_type USED_IF_THREADS,
+ Capability *cap)
{
bdescr *bd;
- step *stp;
- lnat live, allocated, max_copied, avg_copied, slop;
- lnat oldgen_saved_blocks = 0;
+ generation *gen;
+ lnat live_blocks, live_words, allocated, max_copied, avg_copied;
gc_thread *saved_gct;
- nat g, s, t, n;
+ nat g, n;
// necessary if we stole a callee-saves register for gct:
saved_gct = gct;
}
#endif
- ASSERT(sizeof(step_workspace) == 16 * sizeof(StgWord));
- // otherwise adjust the padding in step_workspace.
+ ASSERT(sizeof(gen_workspace) == 16 * sizeof(StgWord));
+ // otherwise adjust the padding in gen_workspace.
+
+ // this is the main thread
+ SET_GCT(gc_threads[cap->no]);
// tell the stats department that we've started a GC
- stat_startGC();
+ stat_startGC(gct);
- // tell the STM to discard any cached closures it's hoping to re-use
- stmPreGCHook();
+ // lock the StablePtr table
+ stablePtrPreGC();
#ifdef DEBUG
mutlist_MUTVARS = 0;
/* Approximate how much we allocated.
* Todo: only when generating stats?
*/
- allocated = calcAllocated();
+ allocated = calcAllocated(rtsFalse/* don't count the nursery yet */);
/* Figure out which generation to collect
*/
n = initialise_N(force_major_gc);
- /* Allocate + initialise the gc_thread structures.
- */
- alloc_gc_threads();
+#if defined(THREADED_RTS)
+ work_stealing = RtsFlags.ParFlags.parGcLoadBalancingEnabled &&
+ N >= RtsFlags.ParFlags.parGcLoadBalancingGen;
+ // It's not always a good idea to do load balancing in parallel
+ // GC. In particular, for a parallel program we don't want to
+ // lose locality by moving cached data into another CPU's cache
+ // (this effect can be quite significant).
+ //
+ // We could have a more complex way to deterimine whether to do
+ // work stealing or not, e.g. it might be a good idea to do it
+ // if the heap is big. For now, we just turn it on or off with
+ // a flag.
+#endif
/* Start threads, so they can be spinning up while we finish initialisation.
*/
start_gc_threads();
+#if defined(THREADED_RTS)
/* How many threads will be participating in this GC?
- * We don't try to parallelise minor GC.
+ * We don't try to parallelise minor GCs (unless the user asks for
+ * it with +RTS -gn0), or mark/compact/sweep GC.
*/
-#if defined(THREADED_RTS)
- if (n < (4*1024*1024 / BLOCK_SIZE)) {
- n_gc_threads = 1;
+ if (gc_type == PENDING_GC_PAR) {
+ n_gc_threads = RtsFlags.ParFlags.nNodes;
} else {
- n_gc_threads = RtsFlags.ParFlags.gcThreads;
+ n_gc_threads = 1;
}
#else
n_gc_threads = 1;
#endif
- trace(TRACE_gc|DEBUG_gc, "GC (gen %d): %dKB to collect, using %d thread(s)",
- N, n * (BLOCK_SIZE / 1024), n_gc_threads);
+
+ debugTrace(DEBUG_gc, "GC (gen %d): %d KB to collect, %ld MB in use, using %d thread(s)",
+ N, n * (BLOCK_SIZE / 1024), mblocks_allocated, n_gc_threads);
#ifdef RTS_GTK_FRONTPANEL
if (RtsFlags.GcFlags.frontpanel) {
#ifdef DEBUG
// check for memory leaks if DEBUG is on
- memInventory(traceClass(DEBUG_gc));
+ memInventory(DEBUG_gc);
#endif
- // check stack sanity *before* GC (ToDo: check all threads)
- IF_DEBUG(sanity, checkFreeListSanity());
-
- // Initialise all our gc_thread structures
- for (t = 0; t < n_gc_threads; t++) {
- init_gc_thread(gc_threads[t]);
- }
+ // check sanity *before* GC
+ IF_DEBUG(sanity, checkSanity(rtsFalse /* before GC */, major_gc));
// Initialise all the generations/steps that we're collecting.
for (g = 0; g <= N; g++) {
- init_collected_gen(g,n_gc_threads);
+ prepare_collected_gen(&generations[g]);
}
-
// Initialise all the generations/steps that we're *not* collecting.
for (g = N+1; g < RtsFlags.GcFlags.generations; g++) {
- init_uncollected_gen(g,n_gc_threads);
+ prepare_uncollected_gen(&generations[g]);
}
+ // Prepare this gc_thread
+ init_gc_thread(gct);
+
/* Allocate a mark stack if we're doing a major collection.
*/
- if (major_gc) {
- mark_stack_bdescr = allocGroup(MARK_STACK_BLOCKS);
- mark_stack = (StgPtr *)mark_stack_bdescr->start;
- mark_sp = mark_stack;
- mark_splim = mark_stack + (MARK_STACK_BLOCKS * BLOCK_SIZE_W);
+ if (major_gc && oldest_gen->mark) {
+ mark_stack_bd = allocBlock();
+ mark_stack_top_bd = mark_stack_bd;
+ mark_stack_bd->link = NULL;
+ mark_stack_bd->u.back = NULL;
+ mark_sp = mark_stack_bd->start;
} else {
- mark_stack_bdescr = NULL;
+ mark_stack_bd = NULL;
+ mark_stack_top_bd = NULL;
+ mark_sp = NULL;
}
- // this is the main thread
- gct = gc_threads[0];
-
/* -----------------------------------------------------------------------
* follow all the roots that we know about:
- * - mutable lists from each generation > N
- * we want to *scavenge* these roots, not evacuate them: they're not
- * going to move in this GC.
- * Also do them in reverse generation order, for the usual reason:
- * namely to reduce the likelihood of spurious old->new pointers.
*/
- for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
- generations[g].saved_mut_list = generations[g].mut_list;
- generations[g].mut_list = allocBlock();
- // mut_list always has at least one block.
- }
// the main thread is running: this prevents any other threads from
// exiting prematurely, so we can start them now.
// NB. do this after the mutable lists have been saved above, otherwise
// the other GC threads will be writing into the old mutable lists.
inc_running();
- wakeup_gc_threads(n_gc_threads);
+ wakeup_gc_threads(gct->thread_index);
+
+ traceEventGcWork(gct->cap);
- for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
- scavenge_mutable_list(&generations[g]);
+ // scavenge the capability-private mutable lists. This isn't part
+ // of markSomeCapabilities() because markSomeCapabilities() can only
+ // call back into the GC via mark_root() (due to the gct register
+ // variable).
+ if (n_gc_threads == 1) {
+ for (n = 0; n < n_capabilities; n++) {
+#if defined(THREADED_RTS)
+ scavenge_capability_mut_Lists1(&capabilities[n]);
+#else
+ scavenge_capability_mut_lists(&capabilities[n]);
+#endif
+ }
+ } else {
+ scavenge_capability_mut_lists(gct->cap);
}
// follow roots from the CAF list (used by GHCi)
- gct->evac_step = 0;
+ gct->evac_gen_no = 0;
markCAFs(mark_root, gct);
// follow all the roots that the application knows about.
- gct->evac_step = 0;
- markSomeCapabilities(mark_root, gct, gct->thread_index, n_gc_threads);
+ gct->evac_gen_no = 0;
+ if (n_gc_threads == 1) {
+ for (n = 0; n < n_capabilities; n++) {
+ markCapability(mark_root, gct, &capabilities[n],
+ rtsTrue/*don't mark sparks*/);
+ }
+ } else {
+ markCapability(mark_root, gct, cap, rtsTrue/*don't mark sparks*/);
+ }
+
+ markScheduler(mark_root, gct);
#if defined(RTS_USER_SIGNALS)
// mark the signal handlers (signals should be already blocked)
*/
for (;;)
{
- gc_thread_work();
+ scavenge_until_all_done();
// The other threads are now stopped. We might recurse back to
// here, but from now on this is the only thread.
- // if any blackholes are alive, make the threads that wait on
- // them alive too.
- if (traverseBlackholeQueue()) {
- inc_running();
- continue;
- }
-
// must be last... invariant is that everything is fully
// scavenged at this point.
if (traverseWeakPtrList()) { // returns rtsTrue if evaced something
break;
}
- shutdown_gc_threads(n_gc_threads);
-
- // Update pointers from the Task list
- update_task_list();
+ shutdown_gc_threads(gct->thread_index);
// Now see which stable names are still alive.
gcStablePtrTable();
+#ifdef THREADED_RTS
+ if (n_gc_threads == 1) {
+ for (n = 0; n < n_capabilities; n++) {
+ pruneSparkQueue(&capabilities[n]);
+ }
+ } else {
+ pruneSparkQueue(gct->cap);
+ }
+#endif
+
#ifdef PROFILING
// We call processHeapClosureForDead() on every closure destroyed during
// the current garbage collection, so we invoke LdvCensusForDead().
#endif
// NO MORE EVACUATION AFTER THIS POINT!
- // Finally: compaction of the oldest generation.
- if (major_gc && oldest_gen->steps[0].is_compacted) {
- // save number of blocks for stats
- oldgen_saved_blocks = oldest_gen->steps[0].n_old_blocks;
- compact(gct->scavenged_static_objects);
- }
-
- IF_DEBUG(sanity, checkGlobalTSOList(rtsFalse));
// Two-space collector: free the old to-space.
- // g0s0->old_blocks is the old nursery
- // g0s0->blocks is to-space from the previous GC
+ // g0->old_blocks is the old nursery
+ // g0->blocks is to-space from the previous GC
if (RtsFlags.GcFlags.generations == 1) {
- if (g0s0->blocks != NULL) {
- freeChain(g0s0->blocks);
- g0s0->blocks = NULL;
- }
- }
-
- // For each workspace, in each thread:
- // * clear the BF_EVACUATED flag from each copied block
- // * move the copied blocks to the step
- {
- gc_thread *thr;
- step_workspace *ws;
- bdescr *prev, *next;
-
- for (t = 0; t < n_gc_threads; t++) {
- thr = gc_threads[t];
-
- // not step 0
- for (s = 1; s < total_steps; s++) {
- ws = &thr->steps[s];
-
- // Push the final block
- if (ws->todo_bd) {
- push_scanned_block(ws->todo_bd, ws);
- }
-
- ASSERT(gct->scan_bd == NULL);
- ASSERT(countBlocks(ws->scavd_list) == ws->n_scavd_blocks);
-
- prev = NULL;
- for (bd = ws->scavd_list; bd != NULL; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED; // now from-space
- ws->step->n_words += bd->free - bd->start;
- prev = bd;
- }
- if (prev != NULL) {
- prev->link = ws->step->blocks;
- ws->step->blocks = ws->scavd_list;
- }
- ws->step->n_blocks += ws->n_scavd_blocks;
-
- prev = NULL;
- for (bd = ws->part_list; bd != NULL; bd = next) {
- next = bd->link;
- if (bd->free == bd->start) {
- if (prev == NULL) {
- ws->part_list = next;
- } else {
- prev->link = next;
- }
- freeGroup(bd);
- ws->n_part_blocks--;
- } else {
- bd->flags &= ~BF_EVACUATED; // now from-space
- ws->step->n_words += bd->free - bd->start;
- prev = bd;
- }
- }
- if (prev != NULL) {
- prev->link = ws->step->blocks;
- ws->step->blocks = ws->part_list;
- }
- ws->step->n_blocks += ws->n_part_blocks;
-
- ASSERT(countBlocks(ws->step->blocks) == ws->step->n_blocks);
- ASSERT(countOccupied(ws->step->blocks) == ws->step->n_words);
- }
+ if (g0->blocks != NULL) {
+ freeChain(g0->blocks);
+ g0->blocks = NULL;
}
}
- // Two-space collector: swap the semi-spaces around.
- // Currently: g0s0->old_blocks is the old nursery
- // g0s0->blocks is to-space from this GC
- // We want these the other way around.
- if (RtsFlags.GcFlags.generations == 1) {
- bdescr *nursery_blocks = g0s0->old_blocks;
- nat n_nursery_blocks = g0s0->n_old_blocks;
- g0s0->old_blocks = g0s0->blocks;
- g0s0->n_old_blocks = g0s0->n_blocks;
- g0s0->blocks = nursery_blocks;
- g0s0->n_blocks = n_nursery_blocks;
+ // Finally: compact or sweep the oldest generation.
+ if (major_gc && oldest_gen->mark) {
+ if (oldest_gen->compact)
+ compact(gct->scavenged_static_objects);
+ else
+ sweep(oldest_gen);
}
- /* run through all the generations/steps and tidy up
- */
copied = 0;
max_copied = 0;
avg_copied = 0;
nat i;
for (i=0; i < n_gc_threads; i++) {
if (n_gc_threads > 1) {
- trace(TRACE_gc,"thread %d:", i);
- trace(TRACE_gc," copied %ld", gc_threads[i]->copied * sizeof(W_));
- trace(TRACE_gc," scanned %ld", gc_threads[i]->scanned * sizeof(W_));
- trace(TRACE_gc," any_work %ld", gc_threads[i]->any_work);
- trace(TRACE_gc," no_work %ld", gc_threads[i]->no_work);
- trace(TRACE_gc," scav_find_work %ld", gc_threads[i]->scav_find_work);
+ debugTrace(DEBUG_gc,"thread %d:", i);
+ debugTrace(DEBUG_gc," copied %ld", gc_threads[i]->copied * sizeof(W_));
+ debugTrace(DEBUG_gc," scanned %ld", gc_threads[i]->scanned * sizeof(W_));
+ debugTrace(DEBUG_gc," any_work %ld", gc_threads[i]->any_work);
+ debugTrace(DEBUG_gc," no_work %ld", gc_threads[i]->no_work);
+ debugTrace(DEBUG_gc," scav_find_work %ld", gc_threads[i]->scav_find_work);
}
copied += gc_threads[i]->copied;
max_copied = stg_max(gc_threads[i]->copied, max_copied);
}
}
+ // Run through all the generations/steps and tidy up.
+ // We're going to:
+ // - count the amount of "live" data (live_words, live_blocks)
+ // - count the amount of "copied" data in this GC (copied)
+ // - free from-space
+ // - make to-space the new from-space (set BF_EVACUATED on all blocks)
+ //
+ live_words = 0;
+ live_blocks = 0;
+
for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
if (g == N) {
// stats. Every mutable list is copied during every GC.
if (g > 0) {
nat mut_list_size = 0;
- for (bd = generations[g].mut_list; bd != NULL; bd = bd->link) {
- mut_list_size += bd->free - bd->start;
- }
+ for (n = 0; n < n_capabilities; n++) {
+ mut_list_size += countOccupied(capabilities[n].mut_lists[g]);
+ }
copied += mut_list_size;
debugTrace(DEBUG_gc,
mutlist_MUTVARS, mutlist_MUTARRS, mutlist_MVARS, mutlist_OTHERS);
}
- for (s = 0; s < generations[g].n_steps; s++) {
- bdescr *next;
- stp = &generations[g].steps[s];
+ bdescr *next, *prev;
+ gen = &generations[g];
- // for generations we collected...
- if (g <= N) {
+ // for generations we collected...
+ if (g <= N) {
/* free old memory and shift to-space into from-space for all
* the collected steps (except the allocation area). These
* freed blocks will probaby be quickly recycled.
*/
- if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
- if (stp->is_compacted)
- {
- // for a compacted step, just shift the new to-space
- // onto the front of the now-compacted existing blocks.
- for (bd = stp->blocks; bd != NULL; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED; // now from-space
- stp->n_words += bd->free - bd->start;
- }
- // tack the new blocks on the end of the existing blocks
- if (stp->old_blocks != NULL) {
- for (bd = stp->old_blocks; bd != NULL; bd = next) {
- // NB. this step might not be compacted next
- // time, so reset the BF_COMPACTED flags.
- // They are set before GC if we're going to
- // compact. (search for BF_COMPACTED above).
- bd->flags &= ~BF_COMPACTED;
- next = bd->link;
- if (next == NULL) {
- bd->link = stp->blocks;
- }
- }
- stp->blocks = stp->old_blocks;
- }
- // add the new blocks to the block tally
- stp->n_blocks += stp->n_old_blocks;
- ASSERT(countBlocks(stp->blocks) == stp->n_blocks);
- ASSERT(countOccupied(stp->blocks) == stp->n_words);
- }
- else // not copacted
- {
- freeChain(stp->old_blocks);
- }
- stp->old_blocks = NULL;
- stp->n_old_blocks = 0;
- }
-
- /* LARGE OBJECTS. The current live large objects are chained on
- * scavenged_large, having been moved during garbage
- * collection from large_objects. Any objects left on
- * large_objects list are therefore dead, so we free them here.
- */
- for (bd = stp->large_objects; bd != NULL; bd = next) {
- next = bd->link;
- freeGroup(bd);
- bd = next;
- }
-
- // update the count of blocks used by large objects
- for (bd = stp->scavenged_large_objects; bd != NULL; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED;
- }
- stp->large_objects = stp->scavenged_large_objects;
- stp->n_large_blocks = stp->n_scavenged_large_blocks;
+ if (gen->mark)
+ {
+ // tack the new blocks on the end of the existing blocks
+ if (gen->old_blocks != NULL) {
+
+ prev = NULL;
+ for (bd = gen->old_blocks; bd != NULL; bd = next) {
+
+ next = bd->link;
+
+ if (!(bd->flags & BF_MARKED))
+ {
+ if (prev == NULL) {
+ gen->old_blocks = next;
+ } else {
+ prev->link = next;
+ }
+ freeGroup(bd);
+ gen->n_old_blocks--;
+ }
+ else
+ {
+ gen->n_words += bd->free - bd->start;
+
+ // NB. this step might not be compacted next
+ // time, so reset the BF_MARKED flags.
+ // They are set before GC if we're going to
+ // compact. (search for BF_MARKED above).
+ bd->flags &= ~BF_MARKED;
+
+ // between GCs, all blocks in the heap except
+ // for the nursery have the BF_EVACUATED flag set.
+ bd->flags |= BF_EVACUATED;
+
+ prev = bd;
+ }
+ }
+
+ if (prev != NULL) {
+ prev->link = gen->blocks;
+ gen->blocks = gen->old_blocks;
+ }
+ }
+ // add the new blocks to the block tally
+ gen->n_blocks += gen->n_old_blocks;
+ ASSERT(countBlocks(gen->blocks) == gen->n_blocks);
+ ASSERT(countOccupied(gen->blocks) == gen->n_words);
+ }
+ else // not copacted
+ {
+ freeChain(gen->old_blocks);
+ }
- }
- else // for older generations...
- {
+ gen->old_blocks = NULL;
+ gen->n_old_blocks = 0;
+
+ /* LARGE OBJECTS. The current live large objects are chained on
+ * scavenged_large, having been moved during garbage
+ * collection from large_objects. Any objects left on the
+ * large_objects list are therefore dead, so we free them here.
+ */
+ freeChain(gen->large_objects);
+ gen->large_objects = gen->scavenged_large_objects;
+ gen->n_large_blocks = gen->n_scavenged_large_blocks;
+ gen->n_new_large_words = 0;
+ }
+ else // for generations > N
+ {
/* For older generations, we need to append the
* scavenged_large_object list (i.e. large objects that have been
* promoted during this GC) to the large_object list for that step.
*/
- for (bd = stp->scavenged_large_objects; bd; bd = next) {
- next = bd->link;
- bd->flags &= ~BF_EVACUATED;
- dbl_link_onto(bd, &stp->large_objects);
+ for (bd = gen->scavenged_large_objects; bd; bd = next) {
+ next = bd->link;
+ dbl_link_onto(bd, &gen->large_objects);
}
-
+
// add the new blocks we promoted during this GC
- stp->n_large_blocks += stp->n_scavenged_large_blocks;
- }
+ gen->n_large_blocks += gen->n_scavenged_large_blocks;
}
- }
+
+ ASSERT(countBlocks(gen->large_objects) == gen->n_large_blocks);
+
+ gen->scavenged_large_objects = NULL;
+ gen->n_scavenged_large_blocks = 0;
+
+ // Count "live" data
+ live_words += genLiveWords(gen);
+ live_blocks += genLiveBlocks(gen);
+
+ // add in the partial blocks in the gen_workspaces, but ignore gen 0
+ // if this is a local GC (we can't count another capability's part_list)
+ {
+ nat i;
+ for (i = 0; i < n_capabilities; i++) {
+ live_words += gcThreadLiveWords(i, gen->no);
+ live_blocks += gcThreadLiveBlocks(i, gen->no);
+ }
+ }
+ } // for all generations
// update the max size of older generations after a major GC
resize_generations();
- // Calculate the amount of live data for stats.
- live = calcLiveWords();
-
- // Free the small objects allocated via allocate(), since this will
- // all have been copied into G0S1 now.
- if (RtsFlags.GcFlags.generations > 1) {
- if (g0s0->blocks != NULL) {
- freeChain(g0s0->blocks);
- g0s0->blocks = NULL;
- }
- g0s0->n_blocks = 0;
- g0s0->n_words = 0;
- }
- alloc_blocks = 0;
- alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize;
-
// Start a new pinned_object_block
- pinned_object_block = NULL;
+ for (n = 0; n < n_capabilities; n++) {
+ capabilities[n].pinned_object_block = NULL;
+ }
// Free the mark stack.
- if (mark_stack_bdescr != NULL) {
- freeGroup(mark_stack_bdescr);
+ if (mark_stack_top_bd != NULL) {
+ debugTrace(DEBUG_gc, "mark stack: %d blocks",
+ countBlocks(mark_stack_top_bd));
+ freeChain(mark_stack_top_bd);
}
// Free any bitmaps.
for (g = 0; g <= N; g++) {
- for (s = 0; s < generations[g].n_steps; s++) {
- stp = &generations[g].steps[s];
- if (stp->bitmap != NULL) {
- freeGroup(stp->bitmap);
- stp->bitmap = NULL;
- }
+ gen = &generations[g];
+ if (gen->bitmap != NULL) {
+ freeGroup(gen->bitmap);
+ gen->bitmap = NULL;
}
}
+ // Reset the nursery: make the blocks empty
+ allocated += clearNurseries();
+
resize_nursery();
- // mark the garbage collected CAFs as dead
+ resetNurseries();
+
+ // mark the garbage collected CAFs as dead
#if 0 && defined(DEBUG) // doesn't work at the moment
if (major_gc) { gcCAFs(); }
#endif
}
}
- // Reset the nursery
- resetNurseries();
+ // Update the stable pointer hash table.
+ updateStablePtrTable(major_gc);
+
+ // unlock the StablePtr table. Must be before scheduleFinalizers(),
+ // because a finalizer may call hs_free_fun_ptr() or
+ // hs_free_stable_ptr(), both of which access the StablePtr table.
+ stablePtrPostGC();
- // start any pending finalizers
+ // Start any pending finalizers. Must be after
+ // updateStablePtrTable() and stablePtrPostGC() (see #4221).
RELEASE_SM_LOCK;
- scheduleFinalizers(last_free_capability, old_weak_ptr_list);
+ scheduleFinalizers(cap, old_weak_ptr_list);
ACQUIRE_SM_LOCK;
-
- // send exceptions to any threads which were about to die
+
+ // check sanity after GC
+ // before resurrectThreads(), because that might overwrite some
+ // closures, which will cause problems with THREADED where we don't
+ // fill slop.
+ IF_DEBUG(sanity, checkSanity(rtsTrue /* after GC */, major_gc));
+
+ // send exceptions to any threads which were about to die
RELEASE_SM_LOCK;
resurrectThreads(resurrected_threads);
ACQUIRE_SM_LOCK;
- // Update the stable pointer hash table.
- updateStablePtrTable(major_gc);
-
- // check sanity after GC
- IF_DEBUG(sanity, checkSanity());
+ if (major_gc) {
+ nat need, got;
+ need = BLOCKS_TO_MBLOCKS(n_alloc_blocks);
+ got = mblocks_allocated;
+ /* If the amount of data remains constant, next major GC we'll
+ require (F+1)*need. We leave (F+2)*need in order to reduce
+ repeated deallocation and reallocation. */
+ need = (RtsFlags.GcFlags.oldGenFactor + 2) * need;
+ if (got > need) {
+ returnMemoryToOS(got - need);
+ }
+ }
- // extra GC trace info
- if (traceClass(TRACE_gc|DEBUG_gc)) statDescribeGens();
+ // extra GC trace info
+ IF_DEBUG(gc, statDescribeGens());
#ifdef DEBUG
// symbol-table based profiling
#ifdef DEBUG
// check for memory leaks if DEBUG is on
- memInventory(traceClass(DEBUG_gc));
+ memInventory(DEBUG_gc);
#endif
#ifdef RTS_GTK_FRONTPANEL
#endif
// ok, GC over: tell the stats department what happened.
- slop = calcLiveBlocks() * BLOCK_SIZE_W - live;
- stat_endGC(allocated, live, copied, N, max_copied, avg_copied, slop);
+ stat_endGC(gct, allocated, live_words,
+ copied, N, max_copied, avg_copied,
+ live_blocks * BLOCK_SIZE_W - live_words /* slop */);
+
+ // Guess which generation we'll collect *next* time
+ initialise_N(force_major_gc);
#if defined(RTS_USER_SIGNALS)
if (RtsFlags.MiscFlags.install_signal_handlers) {
RELEASE_SM_LOCK;
- gct = saved_gct;
+ SET_GCT(saved_gct);
}
/* -----------------------------------------------------------------------------
initialise_N (rtsBool force_major_gc)
{
int g;
- nat s, blocks, blocks_total;
+ nat blocks, blocks_total;
blocks = 0;
blocks_total = 0;
}
for (g = RtsFlags.GcFlags.generations - 1; g >= 0; g--) {
- blocks = 0;
- for (s = 0; s < generations[g].n_steps; s++) {
- blocks += generations[g].steps[s].n_words / BLOCK_SIZE_W;
- blocks += generations[g].steps[s].n_large_blocks;
- }
+
+ blocks = generations[g].n_words / BLOCK_SIZE_W
+ + generations[g].n_large_blocks;
+
if (blocks >= generations[g].max_blocks) {
N = stg_max(N,g);
}
Initialise the gc_thread structures.
-------------------------------------------------------------------------- */
-static gc_thread *
-alloc_gc_thread (int n)
+#define GC_THREAD_INACTIVE 0
+#define GC_THREAD_STANDING_BY 1
+#define GC_THREAD_RUNNING 2
+#define GC_THREAD_WAITING_TO_CONTINUE 3
+
+static void
+new_gc_thread (nat n, gc_thread *t)
{
- nat s;
- step_workspace *ws;
- gc_thread *t;
+ nat g;
+ gen_workspace *ws;
- t = stgMallocBytes(sizeof(gc_thread) + total_steps * sizeof(step_workspace),
- "alloc_gc_thread");
+ t->cap = &capabilities[n];
#ifdef THREADED_RTS
t->id = 0;
- initCondition(&t->wake_cond);
- initMutex(&t->wake_mutex);
- t->wakeup = rtsTrue; // starts true, so we can wait for the
+ initSpinLock(&t->gc_spin);
+ initSpinLock(&t->mut_spin);
+ ACQUIRE_SPIN_LOCK(&t->gc_spin);
+ t->wakeup = GC_THREAD_INACTIVE; // starts true, so we can wait for the
// thread to start up, see wakeup_gc_threads
- t->exit = rtsFalse;
#endif
t->thread_index = n;
t->papi_events = -1;
#endif
- for (s = 0; s < total_steps; s++)
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++)
{
- ws = &t->steps[s];
- ws->step = &all_steps[s];
- ASSERT(s == ws->step->abs_no);
- ws->gct = t;
-
- ws->todo_bd = NULL;
- ws->buffer_todo_bd = NULL;
+ ws = &t->gens[g];
+ ws->gen = &generations[g];
+ ASSERT(g == ws->gen->no);
+ ws->my_gct = t;
+ // We want to call
+ // alloc_todo_block(ws,0);
+ // but can't, because it uses gct which isn't set up at this point.
+ // Hence, allocate a block for todo_bd manually:
+ {
+ bdescr *bd = allocBlock(); // no lock, locks aren't initialised yet
+ initBdescr(bd, ws->gen, ws->gen->to);
+ bd->flags = BF_EVACUATED;
+ bd->u.scan = bd->free = bd->start;
+
+ ws->todo_bd = bd;
+ ws->todo_free = bd->free;
+ ws->todo_lim = bd->start + BLOCK_SIZE_W;
+ }
+
+ ws->todo_q = newWSDeque(128);
+ ws->todo_overflow = NULL;
+ ws->n_todo_overflow = 0;
+ ws->todo_large_objects = NULL;
+
ws->part_list = NULL;
ws->n_part_blocks = 0;
ws->scavd_list = NULL;
ws->n_scavd_blocks = 0;
}
-
- return t;
}
-static void
-alloc_gc_threads (void)
+void
+initGcThreads (void)
{
if (gc_threads == NULL) {
#if defined(THREADED_RTS)
nat i;
- gc_threads = stgMallocBytes (RtsFlags.ParFlags.gcThreads *
+ gc_threads = stgMallocBytes (RtsFlags.ParFlags.nNodes *
sizeof(gc_thread*),
"alloc_gc_threads");
- for (i = 0; i < RtsFlags.ParFlags.gcThreads; i++) {
- gc_threads[i] = alloc_gc_thread(i);
+ for (i = 0; i < RtsFlags.ParFlags.nNodes; i++) {
+ gc_threads[i] =
+ stgMallocBytes(sizeof(gc_thread) +
+ RtsFlags.GcFlags.generations * sizeof(gen_workspace),
+ "alloc_gc_threads");
+
+ new_gc_thread(i, gc_threads[i]);
}
#else
- gc_threads = stgMallocBytes (sizeof(gc_thread*),
- "alloc_gc_threads");
+ gc_threads = stgMallocBytes (sizeof(gc_thread*),"alloc_gc_threads");
+ gc_threads[0] = gct;
+ new_gc_thread(0,gc_threads[0]);
+#endif
+ }
+}
- gc_threads[0] = alloc_gc_thread(0);
+void
+freeGcThreads (void)
+{
+ nat g;
+ if (gc_threads != NULL) {
+#if defined(THREADED_RTS)
+ nat i;
+ for (i = 0; i < n_capabilities; i++) {
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++)
+ {
+ freeWSDeque(gc_threads[i]->gens[g].todo_q);
+ }
+ stgFree (gc_threads[i]);
+ }
+ stgFree (gc_threads);
+#else
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++)
+ {
+ freeWSDeque(gc_threads[0]->gens[g].todo_q);
+ }
+ stgFree (gc_threads);
#endif
+ gc_threads = NULL;
}
}
Start GC threads
------------------------------------------------------------------------- */
-static nat gc_running_threads;
-
-#if defined(THREADED_RTS)
-static Mutex gc_running_mutex;
-#endif
+static volatile StgWord gc_running_threads;
-static nat
+static StgWord
inc_running (void)
{
- nat n_running;
- ACQUIRE_LOCK(&gc_running_mutex);
- n_running = ++gc_running_threads;
- RELEASE_LOCK(&gc_running_mutex);
- ASSERT(n_running <= n_gc_threads);
- return n_running;
+ StgWord new;
+ new = atomic_inc(&gc_running_threads);
+ ASSERT(new <= n_gc_threads);
+ return new;
}
-static nat
+static StgWord
dec_running (void)
{
- nat n_running;
- ACQUIRE_LOCK(&gc_running_mutex);
- ASSERT(n_gc_threads != 0);
- n_running = --gc_running_threads;
- RELEASE_LOCK(&gc_running_mutex);
- return n_running;
+ ASSERT(gc_running_threads != 0);
+ return atomic_dec(&gc_running_threads);
}
-//
-// gc_thread_work(): Scavenge until there's no work left to do and all
-// the running threads are idle.
-//
+static rtsBool
+any_work (void)
+{
+ int g;
+ gen_workspace *ws;
+
+ gct->any_work++;
+
+ write_barrier();
+
+ // scavenge objects in compacted generation
+ if (mark_stack_bd != NULL && !mark_stack_empty()) {
+ return rtsTrue;
+ }
+
+ // Check for global work in any step. We don't need to check for
+ // local work, because we have already exited scavenge_loop(),
+ // which means there is no local work for this thread.
+ for (g = 0; g < (int)RtsFlags.GcFlags.generations; g++) {
+ ws = &gct->gens[g];
+ if (ws->todo_large_objects) return rtsTrue;
+ if (!looksEmptyWSDeque(ws->todo_q)) return rtsTrue;
+ if (ws->todo_overflow) return rtsTrue;
+ }
+
+#if defined(THREADED_RTS)
+ if (work_stealing) {
+ nat n;
+ // look for work to steal
+ for (n = 0; n < n_gc_threads; n++) {
+ if (n == gct->thread_index) continue;
+ for (g = RtsFlags.GcFlags.generations-1; g >= 0; g--) {
+ ws = &gc_threads[n]->gens[g];
+ if (!looksEmptyWSDeque(ws->todo_q)) return rtsTrue;
+ }
+ }
+ }
+#endif
+
+ gct->no_work++;
+#if defined(THREADED_RTS)
+ yieldThread();
+#endif
+
+ return rtsFalse;
+}
+
static void
-gc_thread_work (void)
+scavenge_until_all_done (void)
{
nat r;
- debugTrace(DEBUG_gc, "GC thread %d working", gct->thread_index);
-
- // gc_running_threads has already been incremented for us; either
- // this is the main thread and we incremented it inside
- // GarbageCollect(), or this is a worker thread and the main
- // thread bumped gc_running_threads before waking us up.
-
- // Every thread evacuates some roots.
- gct->evac_step = 0;
- markSomeCapabilities(mark_root, gct, gct->thread_index, n_gc_threads);
loop:
+#if defined(THREADED_RTS)
+ if (n_gc_threads > 1) {
+ scavenge_loop();
+ } else {
+ scavenge_loop1();
+ }
+#else
scavenge_loop();
+#endif
+
+ collect_gct_blocks();
+
// scavenge_loop() only exits when there's no work to do
r = dec_running();
- debugTrace(DEBUG_gc, "GC thread %d idle (%d still running)",
- gct->thread_index, r);
+ traceEventGcIdle(gct->cap);
+ debugTrace(DEBUG_gc, "%d GC threads still running", r);
+
while (gc_running_threads != 0) {
- usleep(1);
- if (any_work()) {
- inc_running();
- goto loop;
- }
- // any_work() does not remove the work from the queue, it
- // just checks for the presence of work. If we find any,
- // then we increment gc_running_threads and go back to
- // scavenge_loop() to perform any pending work.
+ // usleep(1);
+ if (any_work()) {
+ inc_running();
+ traceEventGcWork(gct->cap);
+ goto loop;
+ }
+ // any_work() does not remove the work from the queue, it
+ // just checks for the presence of work. If we find any,
+ // then we increment gc_running_threads and go back to
+ // scavenge_loop() to perform any pending work.
}
- // All threads are now stopped
- debugTrace(DEBUG_gc, "GC thread %d finished.", gct->thread_index);
+ traceEventGcDone(gct->cap);
}
-
#if defined(THREADED_RTS)
-static void
-gc_thread_mainloop (void)
+
+void
+gcWorkerThread (Capability *cap)
{
- while (!gct->exit) {
-
- // Wait until we're told to wake up
- ACQUIRE_LOCK(&gct->wake_mutex);
- gct->wakeup = rtsFalse;
- while (!gct->wakeup) {
- debugTrace(DEBUG_gc, "GC thread %d standing by...",
- gct->thread_index);
- waitCondition(&gct->wake_cond, &gct->wake_mutex);
- }
- RELEASE_LOCK(&gct->wake_mutex);
- if (gct->exit) break;
+ gc_thread *saved_gct;
+
+ // necessary if we stole a callee-saves register for gct:
+ saved_gct = gct;
+
+ gct = gc_threads[cap->no];
+ gct->id = osThreadId();
+
+ stat_gcWorkerThreadStart(gct);
+ // Wait until we're told to wake up
+ RELEASE_SPIN_LOCK(&gct->mut_spin);
+ gct->wakeup = GC_THREAD_STANDING_BY;
+ debugTrace(DEBUG_gc, "GC thread %d standing by...", gct->thread_index);
+ ACQUIRE_SPIN_LOCK(&gct->gc_spin);
+
#ifdef USE_PAPI
- // start performance counters in this thread...
- if (gct->papi_events == -1) {
- papi_init_eventset(&gct->papi_events);
- }
- papi_thread_start_gc1_count(gct->papi_events);
+ // start performance counters in this thread...
+ if (gct->papi_events == -1) {
+ papi_init_eventset(&gct->papi_events);
+ }
+ papi_thread_start_gc1_count(gct->papi_events);
#endif
- gc_thread_work();
+ init_gc_thread(gct);
+
+ traceEventGcWork(gct->cap);
+
+ // Every thread evacuates some roots.
+ gct->evac_gen_no = 0;
+ markCapability(mark_root, gct, cap, rtsTrue/*prune sparks*/);
+ scavenge_capability_mut_lists(cap);
+
+ scavenge_until_all_done();
+
+#ifdef THREADED_RTS
+ // Now that the whole heap is marked, we discard any sparks that
+ // were found to be unreachable. The main GC thread is currently
+ // marking heap reachable via weak pointers, so it is
+ // non-deterministic whether a spark will be retained if it is
+ // only reachable via weak pointers. To fix this problem would
+ // require another GC barrier, which is too high a price.
+ pruneSparkQueue(cap);
+#endif
#ifdef USE_PAPI
- // count events in this thread towards the GC totals
- papi_thread_stop_gc1_count(gct->papi_events);
+ // count events in this thread towards the GC totals
+ papi_thread_stop_gc1_count(gct->papi_events);
#endif
- }
-}
+
+ // Wait until we're told to continue
+ RELEASE_SPIN_LOCK(&gct->gc_spin);
+ gct->wakeup = GC_THREAD_WAITING_TO_CONTINUE;
+ debugTrace(DEBUG_gc, "GC thread %d waiting to continue...",
+ gct->thread_index);
+ ACQUIRE_SPIN_LOCK(&gct->mut_spin);
+ debugTrace(DEBUG_gc, "GC thread %d on my way...", gct->thread_index);
+
+ // record the time spent doing GC in the Task structure
+ stat_gcWorkerThreadDone(gct);
+
+ SET_GCT(saved_gct);
+}
+
#endif
#if defined(THREADED_RTS)
-static void
-gc_thread_entry (gc_thread *my_gct)
+
+void
+waitForGcThreads (Capability *cap USED_IF_THREADS)
{
- gct = my_gct;
- debugTrace(DEBUG_gc, "GC thread %d starting...", gct->thread_index);
- gct->id = osThreadId();
- gc_thread_mainloop();
+ const nat n_threads = RtsFlags.ParFlags.nNodes;
+ const nat me = cap->no;
+ nat i, j;
+ rtsBool retry = rtsTrue;
+
+ while(retry) {
+ for (i=0; i < n_threads; i++) {
+ if (i == me) continue;
+ if (gc_threads[i]->wakeup != GC_THREAD_STANDING_BY) {
+ prodCapability(&capabilities[i], cap->running_task);
+ }
+ }
+ for (j=0; j < 10; j++) {
+ retry = rtsFalse;
+ for (i=0; i < n_threads; i++) {
+ if (i == me) continue;
+ write_barrier();
+ setContextSwitches();
+ if (gc_threads[i]->wakeup != GC_THREAD_STANDING_BY) {
+ retry = rtsTrue;
+ }
+ }
+ if (!retry) break;
+ yieldThread();
+ }
+ }
}
-#endif
+
+#endif // THREADED_RTS
static void
start_gc_threads (void)
{
#if defined(THREADED_RTS)
- nat i;
- OSThreadId id;
- static rtsBool done = rtsFalse;
-
gc_running_threads = 0;
- initMutex(&gc_running_mutex);
-
- if (!done) {
- // Start from 1: the main thread is 0
- for (i = 1; i < RtsFlags.ParFlags.gcThreads; i++) {
- createOSThread(&id, (OSThreadProc*)&gc_thread_entry,
- gc_threads[i]);
- }
- done = rtsTrue;
- }
#endif
}
static void
-wakeup_gc_threads (nat n_threads USED_IF_THREADS)
+wakeup_gc_threads (nat me USED_IF_THREADS)
{
#if defined(THREADED_RTS)
nat i;
- for (i=1; i < n_threads; i++) {
+
+ if (n_gc_threads == 1) return;
+
+ for (i=0; i < n_gc_threads; i++) {
+ if (i == me) continue;
inc_running();
debugTrace(DEBUG_gc, "waking up gc thread %d", i);
- do {
- ACQUIRE_LOCK(&gc_threads[i]->wake_mutex);
- if (gc_threads[i]->wakeup) {
- RELEASE_LOCK(&gc_threads[i]->wake_mutex);
- continue;
- } else {
- break;
- }
- } while (1);
- gc_threads[i]->wakeup = rtsTrue;
- signalCondition(&gc_threads[i]->wake_cond);
- RELEASE_LOCK(&gc_threads[i]->wake_mutex);
+ if (gc_threads[i]->wakeup != GC_THREAD_STANDING_BY) barf("wakeup_gc_threads");
+
+ gc_threads[i]->wakeup = GC_THREAD_RUNNING;
+ ACQUIRE_SPIN_LOCK(&gc_threads[i]->mut_spin);
+ RELEASE_SPIN_LOCK(&gc_threads[i]->gc_spin);
}
#endif
}
// standby state, otherwise they may still be executing inside
// any_work(), and may even remain awake until the next GC starts.
static void
-shutdown_gc_threads (nat n_threads USED_IF_THREADS)
+shutdown_gc_threads (nat me USED_IF_THREADS)
{
#if defined(THREADED_RTS)
nat i;
- rtsBool wakeup;
- for (i=1; i < n_threads; i++) {
- do {
- ACQUIRE_LOCK(&gc_threads[i]->wake_mutex);
- wakeup = gc_threads[i]->wakeup;
- // wakeup is false while the thread is waiting
- RELEASE_LOCK(&gc_threads[i]->wake_mutex);
- } while (wakeup);
+
+ if (n_gc_threads == 1) return;
+
+ for (i=0; i < n_gc_threads; i++) {
+ if (i == me) continue;
+ while (gc_threads[i]->wakeup != GC_THREAD_WAITING_TO_CONTINUE) { write_barrier(); }
}
#endif
}
+#if defined(THREADED_RTS)
+void
+releaseGCThreads (Capability *cap USED_IF_THREADS)
+{
+ const nat n_threads = RtsFlags.ParFlags.nNodes;
+ const nat me = cap->no;
+ nat i;
+ for (i=0; i < n_threads; i++) {
+ if (i == me) continue;
+ if (gc_threads[i]->wakeup != GC_THREAD_WAITING_TO_CONTINUE)
+ barf("releaseGCThreads");
+
+ gc_threads[i]->wakeup = GC_THREAD_INACTIVE;
+ ACQUIRE_SPIN_LOCK(&gc_threads[i]->gc_spin);
+ RELEASE_SPIN_LOCK(&gc_threads[i]->mut_spin);
+ }
+}
+#endif
+
/* ----------------------------------------------------------------------------
Initialise a generation that is to be collected
------------------------------------------------------------------------- */
static void
-init_collected_gen (nat g, nat n_threads)
+prepare_collected_gen (generation *gen)
{
- nat s, t, i;
- step_workspace *ws;
- step *stp;
- bdescr *bd;
+ nat i, g, n;
+ gen_workspace *ws;
+ bdescr *bd, *next;
// Throw away the current mutable list. Invariant: the mutable
// list always has at least one block; this means we can avoid a
// check for NULL in recordMutable().
+ g = gen->no;
if (g != 0) {
- freeChain(generations[g].mut_list);
- generations[g].mut_list = allocBlock();
- for (i = 0; i < n_capabilities; i++) {
+ for (i = 0; i < n_capabilities; i++) {
freeChain(capabilities[i].mut_lists[g]);
capabilities[i].mut_lists[g] = allocBlock();
}
}
- for (s = 0; s < generations[g].n_steps; s++) {
+ gen = &generations[g];
+ ASSERT(gen->no == g);
+
+ // we'll construct a new list of threads in this step
+ // during GC, throw away the current list.
+ gen->old_threads = gen->threads;
+ gen->threads = END_TSO_QUEUE;
+
+ // deprecate the existing blocks
+ gen->old_blocks = gen->blocks;
+ gen->n_old_blocks = gen->n_blocks;
+ gen->blocks = NULL;
+ gen->n_blocks = 0;
+ gen->n_words = 0;
+ gen->live_estimate = 0;
+
+ // initialise the large object queues.
+ ASSERT(gen->scavenged_large_objects == NULL);
+ ASSERT(gen->n_scavenged_large_blocks == 0);
+
+ // grab all the partial blocks stashed in the gc_thread workspaces and
+ // move them to the old_blocks list of this gen.
+ for (n = 0; n < n_capabilities; n++) {
+ ws = &gc_threads[n]->gens[gen->no];
+
+ for (bd = ws->part_list; bd != NULL; bd = next) {
+ next = bd->link;
+ bd->link = gen->old_blocks;
+ gen->old_blocks = bd;
+ gen->n_old_blocks += bd->blocks;
+ }
+ ws->part_list = NULL;
+ ws->n_part_blocks = 0;
- // generation 0, step 0 doesn't need to-space
- if (g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1) {
- continue;
- }
-
- stp = &generations[g].steps[s];
- ASSERT(stp->gen_no == g);
-
- // deprecate the existing blocks
- stp->old_blocks = stp->blocks;
- stp->n_old_blocks = stp->n_blocks;
- stp->blocks = NULL;
- stp->n_blocks = 0;
- stp->n_words = 0;
-
- // we don't have any to-be-scavenged blocks yet
- stp->todos = NULL;
- stp->todos_last = NULL;
- stp->n_todos = 0;
-
- // initialise the large object queues.
- stp->scavenged_large_objects = NULL;
- stp->n_scavenged_large_blocks = 0;
-
- // mark the large objects as not evacuated yet
- for (bd = stp->large_objects; bd; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED;
- }
+ ASSERT(ws->scavd_list == NULL);
+ ASSERT(ws->n_scavd_blocks == 0);
- // for a compacted step, we need to allocate the bitmap
- if (stp->is_compacted) {
- nat bitmap_size; // in bytes
- bdescr *bitmap_bdescr;
- StgWord *bitmap;
-
- bitmap_size = stp->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
-
- if (bitmap_size > 0) {
- bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size)
- / BLOCK_SIZE);
- stp->bitmap = bitmap_bdescr;
- bitmap = bitmap_bdescr->start;
-
- debugTrace(DEBUG_gc, "bitmap_size: %d, bitmap: %p",
- bitmap_size, bitmap);
-
- // don't forget to fill it with zeros!
- memset(bitmap, 0, bitmap_size);
-
- // For each block in this step, point to its bitmap from the
- // block descriptor.
- for (bd=stp->old_blocks; bd != NULL; bd = bd->link) {
- bd->u.bitmap = bitmap;
- bitmap += BLOCK_SIZE_W / (sizeof(W_)*BITS_PER_BYTE);
-
- // Also at this point we set the BF_COMPACTED flag
- // for this block. The invariant is that
- // BF_COMPACTED is always unset, except during GC
- // when it is set on those blocks which will be
- // compacted.
- bd->flags |= BF_COMPACTED;
- }
- }
- }
+ if (ws->todo_free != ws->todo_bd->start) {
+ ws->todo_bd->free = ws->todo_free;
+ ws->todo_bd->link = gen->old_blocks;
+ gen->old_blocks = ws->todo_bd;
+ gen->n_old_blocks += ws->todo_bd->blocks;
+ alloc_todo_block(ws,0); // always has one block.
+ }
}
- // For each GC thread, for each step, allocate a "todo" block to
- // store evacuated objects to be scavenged, and a block to store
- // evacuated objects that do not need to be scavenged.
- for (t = 0; t < n_threads; t++) {
- for (s = 0; s < generations[g].n_steps; s++) {
-
- // we don't copy objects into g0s0, unless -G0
- if (g==0 && s==0 && RtsFlags.GcFlags.generations > 1) continue;
-
- ws = &gc_threads[t]->steps[g * RtsFlags.GcFlags.steps + s];
+ // mark the small objects as from-space
+ for (bd = gen->old_blocks; bd; bd = bd->link) {
+ bd->flags &= ~BF_EVACUATED;
+ }
+
+ // mark the large objects as from-space
+ for (bd = gen->large_objects; bd; bd = bd->link) {
+ bd->flags &= ~BF_EVACUATED;
+ }
- ws->todo_large_objects = NULL;
+ // for a compacted generation, we need to allocate the bitmap
+ if (gen->mark) {
+ nat bitmap_size; // in bytes
+ bdescr *bitmap_bdescr;
+ StgWord *bitmap;
+
+ bitmap_size = gen->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
+
+ if (bitmap_size > 0) {
+ bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size)
+ / BLOCK_SIZE);
+ gen->bitmap = bitmap_bdescr;
+ bitmap = bitmap_bdescr->start;
+
+ debugTrace(DEBUG_gc, "bitmap_size: %d, bitmap: %p",
+ bitmap_size, bitmap);
+
+ // don't forget to fill it with zeros!
+ memset(bitmap, 0, bitmap_size);
+
+ // For each block in this step, point to its bitmap from the
+ // block descriptor.
+ for (bd=gen->old_blocks; bd != NULL; bd = bd->link) {
+ bd->u.bitmap = bitmap;
+ bitmap += BLOCK_SIZE_W / (sizeof(W_)*BITS_PER_BYTE);
+
+ // Also at this point we set the BF_MARKED flag
+ // for this block. The invariant is that
+ // BF_MARKED is always unset, except during GC
+ // when it is set on those blocks which will be
+ // compacted.
+ if (!(bd->flags & BF_FRAGMENTED)) {
+ bd->flags |= BF_MARKED;
+ }
+
+ // BF_SWEPT should be marked only for blocks that are being
+ // collected in sweep()
+ bd->flags &= ~BF_SWEPT;
+ }
+ }
+ }
+}
- ws->part_list = NULL;
- ws->n_part_blocks = 0;
- // allocate the first to-space block; extra blocks will be
- // chained on as necessary.
- ws->todo_bd = NULL;
- ws->buffer_todo_bd = NULL;
- alloc_todo_block(ws,0);
+/* ----------------------------------------------------------------------------
+ Save the mutable lists in saved_mut_lists
+ ------------------------------------------------------------------------- */
- ws->scavd_list = NULL;
- ws->n_scavd_blocks = 0;
- }
- }
+static void
+stash_mut_list (Capability *cap, nat gen_no)
+{
+ cap->saved_mut_lists[gen_no] = cap->mut_lists[gen_no];
+ cap->mut_lists[gen_no] = allocBlock_sync();
}
-
/* ----------------------------------------------------------------------------
Initialise a generation that is *not* to be collected
------------------------------------------------------------------------- */
static void
-init_uncollected_gen (nat g, nat threads)
+prepare_uncollected_gen (generation *gen)
{
- nat s, t, i;
- step_workspace *ws;
- step *stp;
- bdescr *bd;
-
- for (s = 0; s < generations[g].n_steps; s++) {
- stp = &generations[g].steps[s];
- stp->scavenged_large_objects = NULL;
- stp->n_scavenged_large_blocks = 0;
+ nat i;
+
+
+ ASSERT(gen->no > 0);
+
+ // save the current mutable lists for this generation, and
+ // allocate a fresh block for each one. We'll traverse these
+ // mutable lists as roots early on in the GC.
+ for (i = 0; i < n_capabilities; i++) {
+ stash_mut_list(&capabilities[i], gen->no);
}
+
+ ASSERT(gen->scavenged_large_objects == NULL);
+ ASSERT(gen->n_scavenged_large_blocks == 0);
+}
+
+/* -----------------------------------------------------------------------------
+ Collect the completed blocks from a GC thread and attach them to
+ the generation.
+ -------------------------------------------------------------------------- */
+
+static void
+collect_gct_blocks (void)
+{
+ nat g;
+ gen_workspace *ws;
+ bdescr *bd, *prev;
- for (t = 0; t < threads; t++) {
- for (s = 0; s < generations[g].n_steps; s++) {
-
- ws = &gc_threads[t]->steps[g * RtsFlags.GcFlags.steps + s];
- stp = ws->step;
-
- ws->buffer_todo_bd = NULL;
- ws->todo_large_objects = NULL;
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
+ ws = &gct->gens[g];
+
+ // there may still be a block attached to ws->todo_bd;
+ // leave it there to use next time.
- ws->part_list = NULL;
- ws->n_part_blocks = 0;
+ if (ws->scavd_list != NULL) {
+ ACQUIRE_SPIN_LOCK(&ws->gen->sync);
- ws->scavd_list = NULL;
- ws->n_scavd_blocks = 0;
+ ASSERT(gct->scan_bd == NULL);
+ ASSERT(countBlocks(ws->scavd_list) == ws->n_scavd_blocks);
+
+ prev = NULL;
+ for (bd = ws->scavd_list; bd != NULL; bd = bd->link) {
+ ws->gen->n_words += bd->free - bd->start;
+ prev = bd;
+ }
+ if (prev != NULL) {
+ prev->link = ws->gen->blocks;
+ ws->gen->blocks = ws->scavd_list;
+ }
+ ws->gen->n_blocks += ws->n_scavd_blocks;
- // If the block at the head of the list in this generation
- // is less than 3/4 full, then use it as a todo block.
- if (stp->blocks && isPartiallyFull(stp->blocks))
- {
- ws->todo_bd = stp->blocks;
- ws->todo_free = ws->todo_bd->free;
- ws->todo_lim = ws->todo_bd->start + BLOCK_SIZE_W;
- stp->blocks = stp->blocks->link;
- stp->n_blocks -= 1;
- stp->n_words -= ws->todo_bd->free - ws->todo_bd->start;
- ws->todo_bd->link = NULL;
- // we must scan from the current end point.
- ws->todo_bd->u.scan = ws->todo_bd->free;
- }
- else
- {
- ws->todo_bd = NULL;
- alloc_todo_block(ws,0);
- }
- }
- }
+ ws->scavd_list = NULL;
+ ws->n_scavd_blocks = 0;
- // Move the private mutable lists from each capability onto the
- // main mutable list for the generation.
- for (i = 0; i < n_capabilities; i++) {
- for (bd = capabilities[i].mut_lists[g];
- bd->link != NULL; bd = bd->link) {
- /* nothing */
- }
- bd->link = generations[g].mut_list;
- generations[g].mut_list = capabilities[i].mut_lists[g];
- capabilities[i].mut_lists[g] = allocBlock();
+ RELEASE_SPIN_LOCK(&ws->gen->sync);
+ }
}
}
t->static_objects = END_OF_STATIC_LIST;
t->scavenged_static_objects = END_OF_STATIC_LIST;
t->scan_bd = NULL;
- t->evac_step = 0;
+ t->mut_lists = t->cap->mut_lists;
+ t->evac_gen_no = 0;
t->failed_to_evac = rtsFalse;
t->eager_promotion = rtsTrue;
t->thunk_selector_depth = 0;
-------------------------------------------------------------------------- */
static void
-mark_root(void *user, StgClosure **root)
+mark_root(void *user USED_IF_THREADS, StgClosure **root)
{
// we stole a register for gct, but this function is called from
// *outside* the GC where the register variable is not in effect,
// incorrect.
gc_thread *saved_gct;
saved_gct = gct;
- gct = user;
+ SET_GCT(user);
evacuate(root);
- gct = saved_gct;
+ SET_GCT(saved_gct);
}
/* -----------------------------------------------------------------------------
}
/* ----------------------------------------------------------------------------
- Update the pointers from the task list
-
- These are treated as weak pointers because we want to allow a main
- thread to get a BlockedOnDeadMVar exception in the same way as any
- other thread. Note that the threads should all have been retained
- by GC by virtue of being on the all_threads list, we're just
- updating pointers here.
- ------------------------------------------------------------------------- */
-
-static void
-update_task_list (void)
-{
- Task *task;
- StgTSO *tso;
- for (task = all_tasks; task != NULL; task = task->all_link) {
- if (!task->stopped && task->tso) {
- ASSERT(task->tso->bound == task);
- tso = (StgTSO *) isAlive((StgClosure *)task->tso);
- if (tso == NULL) {
- barf("task %p: main thread %d has been GC'd",
-#ifdef THREADED_RTS
- (void *)task->id,
-#else
- (void *)task,
-#endif
- task->tso->id);
- }
- task->tso = tso;
- }
- }
-}
-
-/* ----------------------------------------------------------------------------
Reset the sizes of the older generations when we do a major
collection.
nat g;
if (major_gc && RtsFlags.GcFlags.generations > 1) {
- nat live, size, min_alloc;
- nat max = RtsFlags.GcFlags.maxHeapSize;
- nat gens = RtsFlags.GcFlags.generations;
+ nat live, size, min_alloc, words;
+ const nat max = RtsFlags.GcFlags.maxHeapSize;
+ const nat gens = RtsFlags.GcFlags.generations;
// live in the oldest generations
- live = (oldest_gen->steps[0].n_words + BLOCK_SIZE_W - 1) / BLOCK_SIZE_W+
- oldest_gen->steps[0].n_large_blocks;
+ if (oldest_gen->live_estimate != 0) {
+ words = oldest_gen->live_estimate;
+ } else {
+ words = oldest_gen->n_words;
+ }
+ live = (words + BLOCK_SIZE_W - 1) / BLOCK_SIZE_W +
+ oldest_gen->n_large_blocks;
// default max size for all generations except zero
size = stg_max(live * RtsFlags.GcFlags.oldGenFactor,
RtsFlags.GcFlags.minOldGenSize);
+ if (RtsFlags.GcFlags.heapSizeSuggestionAuto) {
+ RtsFlags.GcFlags.heapSizeSuggestion = size;
+ }
+
// minimum size for generation zero
min_alloc = stg_max((RtsFlags.GcFlags.pcFreeHeap * max) / 200,
RtsFlags.GcFlags.minAllocAreaSize);
// Auto-enable compaction when the residency reaches a
// certain percentage of the maximum heap size (default: 30%).
- if (RtsFlags.GcFlags.generations > 1 &&
- (RtsFlags.GcFlags.compact ||
- (max > 0 &&
- oldest_gen->steps[0].n_blocks >
- (RtsFlags.GcFlags.compactThreshold * max) / 100))) {
- oldest_gen->steps[0].is_compacted = 1;
+ if (RtsFlags.GcFlags.compact ||
+ (max > 0 &&
+ oldest_gen->n_blocks >
+ (RtsFlags.GcFlags.compactThreshold * max) / 100)) {
+ oldest_gen->mark = 1;
+ oldest_gen->compact = 1;
// debugBelch("compaction: on\n", live);
} else {
- oldest_gen->steps[0].is_compacted = 0;
+ oldest_gen->mark = 0;
+ oldest_gen->compact = 0;
// debugBelch("compaction: off\n", live);
}
+ if (RtsFlags.GcFlags.sweep) {
+ oldest_gen->mark = 1;
+ }
+
// if we're going to go over the maximum heap size, reduce the
// size of the generations accordingly. The calculation is
// different if compaction is turned on, because we don't need
heapOverflow();
}
- if (oldest_gen->steps[0].is_compacted) {
+ if (oldest_gen->compact) {
if ( (size + (size - 1) * (gens - 2) * 2) + min_alloc > max ) {
size = (max - min_alloc) / ((gens - 1) * 2 - 1);
}
static void
resize_nursery (void)
{
+ const lnat min_nursery = RtsFlags.GcFlags.minAllocAreaSize * n_capabilities;
+
if (RtsFlags.GcFlags.generations == 1)
{ // Two-space collector:
nat blocks;
* performance we get from 3L bytes, reducing to the same
* performance at 2L bytes.
*/
- blocks = g0s0->n_old_blocks;
+ blocks = generations[0].n_blocks;
if ( RtsFlags.GcFlags.maxHeapSize != 0 &&
blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
else
{
blocks *= RtsFlags.GcFlags.oldGenFactor;
- if (blocks < RtsFlags.GcFlags.minAllocAreaSize)
+ if (blocks < min_nursery)
{
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
+ blocks = min_nursery;
}
}
resizeNurseries(blocks);
if (RtsFlags.GcFlags.heapSizeSuggestion)
{
long blocks;
- nat needed = calcNeeded(); // approx blocks needed at next GC
+ const nat needed = calcNeeded(); // approx blocks needed at next GC
/* Guess how much will be live in generation 0 step 0 next time.
* A good approximation is obtained by finding the
- * percentage of g0s0 that was live at the last minor GC.
+ * percentage of g0 that was live at the last minor GC.
*
* We have an accurate figure for the amount of copied data in
* 'copied', but we must convert this to a number of blocks, with
*/
if (N == 0)
{
- g0s0_pcnt_kept = ((copied / (BLOCK_SIZE_W - 10)) * 100)
+ g0_pcnt_kept = ((copied / (BLOCK_SIZE_W - 10)) * 100)
/ countNurseryBlocks();
}
*
* Formula: suggested - needed
* ----------------------------
- * 1 + g0s0_pcnt_kept/100
+ * 1 + g0_pcnt_kept/100
*
* where 'needed' is the amount of memory needed at the next
- * collection for collecting all steps except g0s0.
+ * collection for collecting all gens except g0.
*/
blocks =
(((long)RtsFlags.GcFlags.heapSizeSuggestion - (long)needed) * 100) /
- (100 + (long)g0s0_pcnt_kept);
+ (100 + (long)g0_pcnt_kept);
- if (blocks < (long)RtsFlags.GcFlags.minAllocAreaSize) {
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
+ if (blocks < (long)min_nursery) {
+ blocks = min_nursery;
}
resizeNurseries((nat)blocks);
projects / ghc-hetmet.git / blobdiff