/* -----------------------------------------------------------------------------
*
- * (c) The GHC Team 1998-2006
+ * (c) The GHC Team 1998-2008
*
* Generational garbage collector
*
#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 "Papi.h"
+#include "Stable.h"
#include "GC.h"
+#include "GCThread.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>
+
+/* -----------------------------------------------------------------------------
+ Global variables
+ -------------------------------------------------------------------------- */
/* STATIC OBJECT LIST.
*
* We build up a static object list while collecting generations 0..N,
* which is then appended to the static object list of generation N+1.
*/
-StgClosure* static_objects; // live static objects
-StgClosure* scavenged_static_objects; // static objects scavenged so far
/* N is the oldest generation being collected, where the generations
* are numbered starting at 0. A major GC (indicated by the major_gc
nat N;
rtsBool major_gc;
-/* Youngest generation that objects should be evacuated to in
- * evacuate(). (Logically an argument to evacuate, but it's static
- * a lot of the time so we optimise it into a global variable).
- */
-nat evac_gen;
-
-/* Whether to do eager promotion or not.
- */
-rtsBool eager_promotion;
-
-/* Flag indicating failure to evacuate an object to the desired
- * generation.
- */
-rtsBool failed_to_evac;
-
-/* Saved nursery (used for 2-space collector only)
- */
-static bdescr *saved_nursery;
-static nat saved_n_blocks;
-
/* Data used for allocation area sizing.
*/
-lnat new_blocks; // blocks allocated during this GC
-lnat new_scavd_blocks; // ditto, but depth-first blocks
-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
nat mutlist_MUTVARS,
mutlist_MUTARRS,
+ mutlist_MVARS,
mutlist_OTHERS;
#endif
-/* -----------------------------------------------------------------------------
- Static function declarations
- -------------------------------------------------------------------------- */
-
-static void mark_root ( StgClosure **root );
-
-static void zero_static_object_list ( StgClosure* first_static );
+/* Thread-local data for each GC thread
+ */
+gc_thread **gc_threads = NULL;
-#if 0 && defined(DEBUG)
-static void gcCAFs ( void );
+#if !defined(THREADED_RTS)
+StgWord8 the_gc_thread[sizeof(gc_thread) + 64 * sizeof(gen_workspace)];
#endif
-/* -----------------------------------------------------------------------------
- inline functions etc. for dealing with the mark bitmap & stack.
- -------------------------------------------------------------------------- */
+// Number of threads running in *this* GC. Affects how many
+// step->todos[] lists we have to look in to find work.
+nat n_gc_threads;
-#define MARK_STACK_BLOCKS 4
+// For stats:
+long copied; // *words* copied & scavenged during this GC
-bdescr *mark_stack_bdescr;
-StgPtr *mark_stack;
-StgPtr *mark_sp;
-StgPtr *mark_splim;
+rtsBool work_stealing;
-// 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;
+DECLARE_GCT
/* -----------------------------------------------------------------------------
- GarbageCollect
-
- Rough outline of the algorithm: for garbage collecting generation N
- (and all younger generations):
-
- - follow all pointers in the root set. the root set includes all
- mutable objects in all generations (mutable_list).
+ Static function declarations
+ -------------------------------------------------------------------------- */
- - for each pointer, evacuate the object it points to into either
+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 init_collected_gen (nat g, nat threads);
+static void init_uncollected_gen (nat g, nat threads);
+static void init_gc_thread (gc_thread *t);
+static void resize_generations (void);
+static void resize_nursery (void);
+static void start_gc_threads (void);
+static void scavenge_until_all_done (void);
+static StgWord inc_running (void);
+static StgWord dec_running (void);
+static void wakeup_gc_threads (nat n_threads, nat me);
+static void shutdown_gc_threads (nat n_threads, nat me);
- + to-space of the step given by step->to, which is the next
- highest step in this generation or the first step in the next
- generation if this is the last step.
+#if 0 && defined(DEBUG)
+static void gcCAFs (void);
+#endif
- + to-space of generations[evac_gen]->steps[0], if evac_gen != 0.
- When we evacuate an object we attempt to evacuate
- everything it points to into the same generation - this is
- achieved by setting evac_gen to the desired generation. If
- we can't do this, then an entry in the mut list has to
- be made for the cross-generation pointer.
+/* -----------------------------------------------------------------------------
+ The mark stack.
+ -------------------------------------------------------------------------- */
- + if the object is already in a generation > N, then leave
- it alone.
+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
- - repeatedly scavenge to-space from each step in each generation
- being collected until no more objects can be evacuated.
-
- - free from-space in each step, and set from-space = to-space.
+/* -----------------------------------------------------------------------------
+ GarbageCollect: the main entry point to the garbage collector.
Locks held: all capabilities are held throughout GarbageCollect().
-
-------------------------------------------------------------------------- */
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, copied = 0, scavd_copied = 0;
- lnat oldgen_saved_blocks = 0;
- nat g, s, i;
+ generation *gen;
+ lnat live, allocated, max_copied, avg_copied, slop;
+ gc_thread *saved_gct;
+ nat g, t, n;
- ACQUIRE_SM_LOCK;
+ // necessary if we stole a callee-saves register for gct:
+ saved_gct = gct;
#ifdef PROFILING
CostCentreStack *prev_CCS;
#endif
- debugTrace(DEBUG_gc, "starting GC");
+ ACQUIRE_SM_LOCK;
#if defined(RTS_USER_SIGNALS)
if (RtsFlags.MiscFlags.install_signal_handlers) {
}
#endif
- // tell the STM to discard any cached closures its hoping to re-use
- stmPreGCHook();
+ ASSERT(sizeof(gen_workspace) == 16 * sizeof(StgWord));
+ // otherwise adjust the padding in gen_workspace.
// tell the stats department that we've started a GC
stat_startGC();
-#ifdef DEBUG
- // check for memory leaks if DEBUG is on
- memInventory();
-#endif
+ // 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;
/* Figure out which generation to collect
*/
- if (force_major_gc) {
- N = RtsFlags.GcFlags.generations - 1;
- major_gc = rtsTrue;
+ n = initialise_N(force_major_gc);
+
+#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 GCs (unless the user asks for
+ * it with +RTS -gn0), or mark/compact/sweep GC.
+ */
+ if (gc_type == PENDING_GC_PAR) {
+ n_gc_threads = RtsFlags.ParFlags.nNodes;
} else {
- N = 0;
- for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
- if (generations[g].steps[0].n_blocks +
- generations[g].steps[0].n_large_blocks
- >= generations[g].max_blocks) {
- N = g;
- }
- }
- major_gc = (N == RtsFlags.GcFlags.generations-1);
+ n_gc_threads = 1;
}
+#else
+ n_gc_threads = 1;
+#endif
+
+ 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) {
}
#endif
- // check stack sanity *before* GC (ToDo: check all threads)
- IF_DEBUG(sanity, checkFreeListSanity());
+#ifdef DEBUG
+ // check for memory leaks if DEBUG is on
+ memInventory(DEBUG_gc);
+#endif
- /* Initialise the static object lists
- */
- static_objects = END_OF_STATIC_LIST;
- scavenged_static_objects = END_OF_STATIC_LIST;
+ // check sanity *before* GC
+ IF_DEBUG(sanity, checkSanity(rtsTrue));
- /* Save the nursery if we're doing a two-space collection.
- * g0s0->blocks will be used for to-space, so we need to get the
- * nursery out of the way.
- */
- if (RtsFlags.GcFlags.generations == 1) {
- saved_nursery = g0s0->blocks;
- saved_n_blocks = g0s0->n_blocks;
- g0s0->blocks = NULL;
- g0s0->n_blocks = 0;
+ // Initialise all our gc_thread structures
+ for (t = 0; t < n_gc_threads; t++) {
+ init_gc_thread(gc_threads[t]);
}
- /* Keep a count of how many new blocks we allocated during this GC
- * (used for resizing the allocation area, later).
- */
- new_blocks = 0;
- new_scavd_blocks = 0;
-
- // Initialise to-space in all the generations/steps that we're
- // collecting.
- //
+ // Initialise all the generations/steps that we're collecting.
for (g = 0; g <= N; g++) {
-
- // throw away the mutable list. Invariant: the mutable list
- // always has at least one block; this means we can avoid a check for
- // NULL in recordMutable().
- if (g != 0) {
- freeChain(generations[g].mut_list);
- generations[g].mut_list = allocBlock();
- 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++) {
-
- // 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);
-
- // start a new to-space for this step.
- stp->old_blocks = stp->blocks;
- stp->n_old_blocks = stp->n_blocks;
-
- // allocate the first to-space block; extra blocks will be
- // chained on as necessary.
- stp->hp_bd = NULL;
- bd = gc_alloc_block(stp);
- stp->blocks = bd;
- stp->n_blocks = 1;
- stp->scan = bd->start;
- stp->scan_bd = bd;
-
- // allocate a block for "already scavenged" objects. This goes
- // on the front of the stp->blocks list, so it won't be
- // traversed by the scavenging sweep.
- gc_alloc_scavd_block(stp);
-
- // initialise the large object queues.
- stp->new_large_objects = NULL;
- 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;
- }
-
- // 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;
- }
- }
- }
- }
+ init_collected_gen(g,n_gc_threads);
}
-
- /* make sure the older generations have at least one block to
- * allocate into (this makes things easier for copy(), see below).
- */
+
+ // Initialise all the generations/steps that we're *not* collecting.
for (g = N+1; g < RtsFlags.GcFlags.generations; g++) {
- for (s = 0; s < generations[g].n_steps; s++) {
- stp = &generations[g].steps[s];
- if (stp->hp_bd == NULL) {
- ASSERT(stp->blocks == NULL);
- bd = gc_alloc_block(stp);
- stp->blocks = bd;
- stp->n_blocks = 1;
- }
- if (stp->scavd_hp == NULL) {
- gc_alloc_scavd_block(stp);
- stp->n_blocks++;
- }
- /* Set the scan pointer for older generations: remember we
- * still have to scavenge objects that have been promoted. */
- stp->scan = stp->hp;
- stp->scan_bd = stp->hp_bd;
- stp->new_large_objects = NULL;
- stp->scavenged_large_objects = NULL;
- stp->n_scavenged_large_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();
- }
+ init_uncollected_gen(g,n_gc_threads);
}
/* 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;
}
- eager_promotion = rtsTrue; // for now
+ // this is the main thread
+#ifdef THREADED_RTS
+ if (n_gc_threads == 1) {
+ SET_GCT(gc_threads[0]);
+ } else {
+ SET_GCT(gc_threads[cap->no]);
+ }
+#else
+SET_GCT(gc_threads[0]);
+#endif
/* -----------------------------------------------------------------------
* 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. This is because we
- * often want to promote objects that are pointed to by older
- * generations early, so we don't have to repeatedly copy them.
- * Doing the generations in reverse order ensures that we don't end
- * up in the situation where we want to evac an object to gen 3 and
- * it has already been evaced to gen 2.
*/
- {
- int st;
- 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.
- }
- for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
- scavenge_mutable_list(&generations[g]);
- evac_gen = g;
- for (st = generations[g].n_steps-1; st >= 0; st--) {
- scavenge(&generations[g].steps[st]);
+ // 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, gct->thread_index);
+
+ // 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--) {
+#if defined(THREADED_RTS)
+ if (n_gc_threads > 1) {
+ scavenge_mutable_list(generations[g].saved_mut_list, &generations[g]);
+ } else {
+ scavenge_mutable_list1(generations[g].saved_mut_list, &generations[g]);
}
- }
+#else
+ scavenge_mutable_list(generations[g].saved_mut_list, &generations[g]);
+#endif
+ freeChain_sync(generations[g].saved_mut_list);
+ generations[g].saved_mut_list = NULL;
+
}
- /* follow roots from the CAF list (used by GHCi)
- */
- evac_gen = 0;
- markCAFs(mark_root);
+ // 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(&capabilities[gct->thread_index]);
+ }
- /* follow all the roots that the application knows about.
- */
- evac_gen = 0;
- GetRoots(mark_root);
+ // follow roots from the CAF list (used by GHCi)
+ gct->evac_gen = 0;
+ markCAFs(mark_root, gct);
- /* Mark the weak pointer list, and prepare to detect dead weak
- * pointers.
- */
+ // follow all the roots that the application knows about.
+ gct->evac_gen = 0;
+ markSomeCapabilities(mark_root, gct, gct->thread_index, n_gc_threads,
+ rtsTrue/*prune sparks*/);
+
+#if defined(RTS_USER_SIGNALS)
+ // mark the signal handlers (signals should be already blocked)
+ markSignalHandlers(mark_root, gct);
+#endif
+
+ // Mark the weak pointer list, and prepare to detect dead weak pointers.
markWeakPtrList();
initWeakForGC();
- /* Mark the stable pointer table.
- */
- markStablePtrTable(mark_root);
+ // Mark the stable pointer table.
+ markStablePtrTable(mark_root, gct);
/* -------------------------------------------------------------------------
* Repeatedly scavenge all the areas we know about until there's no
* more scavenging to be done.
*/
- {
- rtsBool flag;
- loop:
- flag = rtsFalse;
-
- // scavenge static objects
- if (major_gc && static_objects != END_OF_STATIC_LIST) {
- IF_DEBUG(sanity, checkStaticObjects(static_objects));
- scavenge_static();
- }
-
- /* When scavenging the older generations: Objects may have been
- * evacuated from generations <= N into older generations, and we
- * need to scavenge these objects. We're going to try to ensure that
- * any evacuations that occur move the objects into at least the
- * same generation as the object being scavenged, otherwise we
- * have to create new entries on the mutable list for the older
- * generation.
- */
-
- // scavenge each step in generations 0..maxgen
- {
- long gen;
- int st;
-
- loop2:
- // scavenge objects in compacted generation
- if (mark_stack_overflowed || oldgen_scan_bd != NULL ||
- (mark_stack_bdescr != NULL && !mark_stack_empty())) {
- scavenge_mark_stack();
- flag = rtsTrue;
- }
-
- for (gen = RtsFlags.GcFlags.generations; --gen >= 0; ) {
- for (st = generations[gen].n_steps; --st >= 0; ) {
- if (gen == 0 && st == 0 && RtsFlags.GcFlags.generations > 1) {
- continue;
- }
- stp = &generations[gen].steps[st];
- evac_gen = gen;
- if (stp->hp_bd != stp->scan_bd || stp->scan < stp->hp) {
- scavenge(stp);
- flag = rtsTrue;
- goto loop2;
- }
- if (stp->new_large_objects != NULL) {
- scavenge_large(stp);
- flag = rtsTrue;
- goto loop2;
- }
- }
+ for (;;)
+ {
+ 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.
+
+ // must be last... invariant is that everything is fully
+ // scavenged at this point.
+ if (traverseWeakPtrList()) { // returns rtsTrue if evaced something
+ inc_running();
+ continue;
}
- }
-
- // if any blackholes are alive, make the threads that wait on
- // them alive too.
- if (traverseBlackholeQueue())
- flag = rtsTrue;
- if (flag) { goto loop; }
-
- // must be last... invariant is that everything is fully
- // scavenged at this point.
- if (traverseWeakPtrList()) { // returns rtsTrue if evaced something
- goto loop;
- }
+ // If we get to here, there's really nothing left to do.
+ break;
}
- /* 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.
- */
- {
- 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;
- }
- }
- }
+ shutdown_gc_threads(n_gc_threads, gct->thread_index);
// Now see which stable names are still alive.
gcStablePtrTable();
- // Tidy the end of the to-space chains
- for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
- for (s = 0; s < generations[g].n_steps; s++) {
- stp = &generations[g].steps[s];
- if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
- ASSERT(Bdescr(stp->hp) == stp->hp_bd);
- stp->hp_bd->free = stp->hp;
- Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
- }
- }
- }
-
#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();
+
+ // Two-space collector: free the old to-space.
+ // g0->old_blocks is the old nursery
+ // g0->blocks is to-space from the previous GC
+ if (RtsFlags.GcFlags.generations == 1) {
+ if (g0->blocks != NULL) {
+ freeChain(g0->blocks);
+ g0->blocks = NULL;
+ }
}
- IF_DEBUG(sanity, checkGlobalTSOList(rtsFalse));
+ // For each workspace, in each thread, move the copied blocks to the step
+ {
+ gc_thread *thr;
+ gen_workspace *ws;
+ bdescr *prev, *next;
+
+ for (t = 0; t < n_gc_threads; t++) {
+ thr = gc_threads[t];
+
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
+ ws = &thr->gens[g];
+
+ // 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) {
+ 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;
+ }
+ }
+
+ // Add all the partial blocks *after* we've added all the full
+ // blocks. This is so that we can grab the partial blocks back
+ // again and try to fill them up in the next GC.
+ for (t = 0; t < n_gc_threads; t++) {
+ thr = gc_threads[t];
+
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
+ ws = &thr->gens[g];
+
+ 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 {
+ ws->gen->n_words += bd->free - bd->start;
+ prev = bd;
+ }
+ }
+ if (prev != NULL) {
+ prev->link = ws->gen->blocks;
+ ws->gen->blocks = ws->part_list;
+ }
+ ws->gen->n_blocks += ws->n_part_blocks;
+
+ ASSERT(countBlocks(ws->gen->blocks) == ws->gen->n_blocks);
+ ASSERT(countOccupied(ws->gen->blocks) == ws->gen->n_words);
+ }
+ }
+ }
+
+ // 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 = new_blocks * BLOCK_SIZE_W;
- scavd_copied = new_scavd_blocks * BLOCK_SIZE_W;
+ copied = 0;
+ max_copied = 0;
+ avg_copied = 0;
+ {
+ nat i;
+ for (i=0; i < n_gc_threads; i++) {
+ if (n_gc_threads > 1) {
+ 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);
+ }
+ if (n_gc_threads == 1) {
+ max_copied = 0;
+ avg_copied = 0;
+ } else {
+ avg_copied = copied;
+ }
+ }
+
for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
- if (g <= N) {
+ if (g == N) {
generations[g].collections++; // for stats
+ if (n_gc_threads > 1) generations[g].par_collections++;
}
// Count the mutable list as bytes "copied" for the purposes of
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++) {
+ for (bd = capabilities[n].mut_lists[g];
+ bd != NULL; bd = bd->link) {
+ mut_list_size += bd->free - bd->start;
+ }
+ }
copied += mut_list_size;
debugTrace(DEBUG_gc,
- "mut_list_size: %lu (%d vars, %d arrays, %d others)",
+ "mut_list_size: %lu (%d vars, %d arrays, %d MVARs, %d others)",
(unsigned long)(mut_list_size * sizeof(W_)),
- mutlist_MUTVARS, mutlist_MUTARRS, mutlist_OTHERS);
+ 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];
- if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
- // stats information: how much we copied
- if (g <= N) {
- copied -= stp->hp_bd->start + BLOCK_SIZE_W -
- stp->hp_bd->free;
- scavd_copied -= stp->scavd_hpLim - stp->scavd_hp;
- }
- }
-
- // 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)) {
- 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
- }
- // 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);
- } else {
- freeChain(stp->old_blocks);
- for (bd = stp->blocks; bd != NULL; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED; // now from-space
- }
- }
- 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;
-
- } else {
- // for older generations...
-
+ 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);
+ }
+
+ 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_blocks = 0;
+ ASSERT(countBlocks(gen->large_objects) == gen->n_large_blocks);
+ }
+ 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);
}
- }
-
- /* Reset the sizes of the older generations when we do a major
- * collection.
- *
- * CURRENT STRATEGY: make all generations except zero the same size.
- * We have to stay within the maximum heap size, and leave a certain
- * percentage of the maximum heap size available to allocate into.
- */
- if (major_gc && RtsFlags.GcFlags.generations > 1) {
- nat live, size, min_alloc;
- nat max = RtsFlags.GcFlags.maxHeapSize;
- nat gens = RtsFlags.GcFlags.generations;
-
- // live in the oldest generations
- live = oldest_gen->steps[0].n_blocks +
- oldest_gen->steps[0].n_large_blocks;
-
- // default max size for all generations except zero
- size = stg_max(live * RtsFlags.GcFlags.oldGenFactor,
- RtsFlags.GcFlags.minOldGenSize);
-
- // 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;
-// debugBelch("compaction: on\n", live);
- } else {
- oldest_gen->steps[0].is_compacted = 0;
-// debugBelch("compaction: off\n", live);
- }
+ } // for all generations
- // 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
- // to double the space required to collect the old generation.
- if (max != 0) {
-
- // this test is necessary to ensure that the calculations
- // below don't have any negative results - we're working
- // with unsigned values here.
- if (max < min_alloc) {
- heapOverflow();
- }
-
- if (oldest_gen->steps[0].is_compacted) {
- if ( (size + (size - 1) * (gens - 2) * 2) + min_alloc > max ) {
- size = (max - min_alloc) / ((gens - 1) * 2 - 1);
- }
- } else {
- if ( (size * (gens - 1) * 2) + min_alloc > max ) {
- size = (max - min_alloc) / ((gens - 1) * 2);
- }
- }
-
- if (size < live) {
- heapOverflow();
- }
- }
-
-#if 0
- debugBelch("live: %d, min_alloc: %d, size : %d, max = %d\n", live,
- min_alloc, size, max);
-#endif
-
- for (g = 0; g < gens; g++) {
- generations[g].max_blocks = size;
- }
- }
-
- // Guess the amount of live data for stats.
- live = calcLive();
+ // 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 (small_alloc_list != NULL) {
- freeChain(small_alloc_list);
- }
- small_alloc_list = NULL;
- alloc_blocks = 0;
- alloc_Hp = NULL;
- alloc_HpLim = NULL;
+ // Free the small objects allocated via allocate(), since this will
+ // all have been copied into G0S1 now.
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);
+ // Free the mark stack.
+ 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.
- */
+ // 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;
}
}
- /* Two-space collector:
- * Free the old to-space, and estimate the amount of live data.
- */
- if (RtsFlags.GcFlags.generations == 1) {
- nat blocks;
-
- if (g0s0->old_blocks != NULL) {
- freeChain(g0s0->old_blocks);
- }
- for (bd = g0s0->blocks; bd != NULL; bd = bd->link) {
- bd->flags = 0; // now from-space
- }
- g0s0->old_blocks = g0s0->blocks;
- g0s0->n_old_blocks = g0s0->n_blocks;
- g0s0->blocks = saved_nursery;
- g0s0->n_blocks = saved_n_blocks;
-
- /* For a two-space collector, we need to resize the nursery. */
-
- /* set up a new nursery. Allocate a nursery size based on a
- * function of the amount of live data (by default a factor of 2)
- * Use the blocks from the old nursery if possible, freeing up any
- * left over blocks.
- *
- * If we get near the maximum heap size, then adjust our nursery
- * size accordingly. If the nursery is the same size as the live
- * data (L), then we need 3L bytes. We can reduce the size of the
- * nursery to bring the required memory down near 2L bytes.
- *
- * A normal 2-space collector would need 4L bytes to give the same
- * performance we get from 3L bytes, reducing to the same
- * performance at 2L bytes.
- */
- blocks = g0s0->n_old_blocks;
-
- if ( RtsFlags.GcFlags.maxHeapSize != 0 &&
- blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
- RtsFlags.GcFlags.maxHeapSize ) {
- long adjusted_blocks; // signed on purpose
- int pc_free;
-
- adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks);
-
- debugTrace(DEBUG_gc, "near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld",
- RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks);
-
- pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize;
- if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ {
- heapOverflow();
- }
- blocks = adjusted_blocks;
-
- } else {
- blocks *= RtsFlags.GcFlags.oldGenFactor;
- if (blocks < RtsFlags.GcFlags.minAllocAreaSize) {
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
- }
- }
- resizeNurseries(blocks);
-
- } else {
- /* Generational collector:
- * If the user has given us a suggested heap size, adjust our
- * allocation area to make best use of the memory available.
- */
-
- if (RtsFlags.GcFlags.heapSizeSuggestion) {
- long blocks;
- 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.
- */
- if (N == 0) {
- g0s0_pcnt_kept = (new_blocks * 100) / countNurseryBlocks();
- }
-
- /* Estimate a size for the allocation area based on the
- * information available. We might end up going slightly under
- * or over the suggested heap size, but we should be pretty
- * close on average.
- *
- * Formula: suggested - needed
- * ----------------------------
- * 1 + g0s0_pcnt_kept/100
- *
- * where 'needed' is the amount of memory needed at the next
- * collection for collecting all steps except g0s0.
- */
- blocks =
- (((long)RtsFlags.GcFlags.heapSizeSuggestion - (long)needed) * 100) /
- (100 + (long)g0s0_pcnt_kept);
-
- if (blocks < (long)RtsFlags.GcFlags.minAllocAreaSize) {
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
- }
-
- resizeNurseries((nat)blocks);
-
- } else {
- // we might have added extra large blocks to the nursery, so
- // resize back to minAllocAreaSize again.
- resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize);
- }
- }
+ resize_nursery();
// mark the garbage collected CAFs as dead
#if 0 && defined(DEBUG) // doesn't work at the moment
#ifdef PROFILING
// resetStaticObjectForRetainerProfiling() must be called before
// zeroing below.
- resetStaticObjectForRetainerProfiling();
+ if (n_gc_threads > 1) {
+ barf("profiling is currently broken with multi-threaded GC");
+ // ToDo: fix the gct->scavenged_static_objects below
+ }
+ resetStaticObjectForRetainerProfiling(gct->scavenged_static_objects);
#endif
// zero the scavenged static object list
if (major_gc) {
- zero_static_object_list(scavenged_static_objects);
+ nat i;
+ for (i = 0; i < n_gc_threads; i++) {
+ zero_static_object_list(gc_threads[i]->scavenged_static_objects);
+ }
}
// Reset the nursery
// start any pending finalizers
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
// Update the stable pointer hash table.
updateStablePtrTable(major_gc);
- // check sanity after GC
- IF_DEBUG(sanity, checkSanity());
+ // check sanity after GC
+ IF_DEBUG(sanity, checkSanity(rtsTrue));
// extra GC trace info
IF_DEBUG(gc, statDescribeGens());
#ifdef DEBUG
// check for memory leaks if DEBUG is on
- memInventory();
+ memInventory(DEBUG_gc);
#endif
#ifdef RTS_GTK_FRONTPANEL
#endif
// ok, GC over: tell the stats department what happened.
- stat_endGC(allocated, live, copied, scavd_copied, N);
+ slop = calcLiveBlocks() * BLOCK_SIZE_W - live;
+ stat_endGC(allocated, live, copied, N, max_copied, avg_copied, slop);
+
+ // unlock the StablePtr table
+ stablePtrPostGC();
+
+ // Guess which generation we'll collect *next* time
+ initialise_N(force_major_gc);
#if defined(RTS_USER_SIGNALS)
if (RtsFlags.MiscFlags.install_signal_handlers) {
#endif
RELEASE_SM_LOCK;
+
+ SET_GCT(saved_gct);
}
/* -----------------------------------------------------------------------------
- isAlive determines whether the given closure is still alive (after
- a garbage collection) or not. It returns the new address of the
- closure if it is alive, or NULL otherwise.
+ Figure out which generation to collect, initialise N and major_gc.
+
+ Also returns the total number of blocks in generations that will be
+ collected.
+ -------------------------------------------------------------------------- */
+
+static nat
+initialise_N (rtsBool force_major_gc)
+{
+ int g;
+ nat blocks, blocks_total;
+
+ blocks = 0;
+ blocks_total = 0;
+
+ if (force_major_gc) {
+ N = RtsFlags.GcFlags.generations - 1;
+ } else {
+ N = 0;
+ }
- NOTE: Use it before compaction only!
- It untags and (if needed) retags pointers to closures.
+ for (g = RtsFlags.GcFlags.generations - 1; g >= 0; g--) {
+
+ blocks = generations[g].n_words / BLOCK_SIZE_W
+ + generations[g].n_large_blocks;
+
+ if (blocks >= generations[g].max_blocks) {
+ N = stg_max(N,g);
+ }
+ if ((nat)g <= N) {
+ blocks_total += blocks;
+ }
+ }
+
+ blocks_total += countNurseryBlocks();
+
+ major_gc = (N == RtsFlags.GcFlags.generations-1);
+ return blocks_total;
+}
+
+/* -----------------------------------------------------------------------------
+ Initialise the gc_thread structures.
-------------------------------------------------------------------------- */
+#define GC_THREAD_INACTIVE 0
+#define GC_THREAD_STANDING_BY 1
+#define GC_THREAD_RUNNING 2
+#define GC_THREAD_WAITING_TO_CONTINUE 3
-StgClosure *
-isAlive(StgClosure *p)
+static void
+new_gc_thread (nat n, gc_thread *t)
{
- const StgInfoTable *info;
- bdescr *bd;
- StgWord tag;
+ nat g;
+ gen_workspace *ws;
- while (1) {
- /* The tag and the pointer are split, to be merged later when needed. */
- tag = GET_CLOSURE_TAG(p);
- p = UNTAG_CLOSURE(p);
+#ifdef THREADED_RTS
+ t->id = 0;
+ 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
+#endif
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
- info = get_itbl(p);
+ t->thread_index = n;
+ t->free_blocks = NULL;
+ t->gc_count = 0;
- // ignore static closures
- //
- // ToDo: for static closures, check the static link field.
- // Problem here is that we sometimes don't set the link field, eg.
- // for static closures with an empty SRT or CONSTR_STATIC_NOCAFs.
- //
- if (!HEAP_ALLOCED(p)) {
- return TAG_CLOSURE(tag,p);
+ init_gc_thread(t);
+
+#ifdef USE_PAPI
+ t->papi_events = -1;
+#endif
+
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++)
+ {
+ ws = &t->gens[g];
+ ws->gen = &generations[g];
+ ASSERT(g == ws->gen->no);
+ ws->my_gct = t;
+
+ ws->todo_bd = NULL;
+ ws->todo_q = newWSDeque(128);
+ ws->todo_overflow = NULL;
+ ws->n_todo_overflow = 0;
+
+ ws->part_list = NULL;
+ ws->n_part_blocks = 0;
+
+ ws->scavd_list = NULL;
+ ws->n_scavd_blocks = 0;
}
+}
+
- // ignore closures in generations that we're not collecting.
- bd = Bdescr((P_)p);
- if (bd->gen_no > N) {
- return TAG_CLOSURE(tag,p);
+void
+initGcThreads (void)
+{
+ if (gc_threads == NULL) {
+#if defined(THREADED_RTS)
+ nat i;
+ gc_threads = stgMallocBytes (RtsFlags.ParFlags.nNodes *
+ sizeof(gc_thread*),
+ "alloc_gc_threads");
+
+ 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[0] = gct;
+ new_gc_thread(0,gc_threads[0]);
+#endif
}
+}
- // if it's a pointer into to-space, then we're done
- if (bd->flags & BF_EVACUATED) {
- return TAG_CLOSURE(tag,p);
+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 volatile StgWord gc_running_threads;
+
+static StgWord
+inc_running (void)
+{
+ StgWord new;
+ new = atomic_inc(&gc_running_threads);
+ ASSERT(new <= n_gc_threads);
+ return new;
+}
+
+static StgWord
+dec_running (void)
+{
+ ASSERT(gc_running_threads != 0);
+ return atomic_dec(&gc_running_threads);
+}
+
+static rtsBool
+any_work (void)
+{
+ int g;
+ gen_workspace *ws;
+
+ gct->any_work++;
- // large objects use the evacuated flag
- if (bd->flags & BF_LARGE) {
- return NULL;
+ 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;
}
- // check the mark bit for compacted steps
- if ((bd->flags & BF_COMPACTED) && is_marked((P_)p,bd)) {
- return TAG_CLOSURE(tag,p);
+#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
- switch (info->type) {
-
- case IND:
- case IND_STATIC:
- case IND_PERM:
- case IND_OLDGEN: // rely on compatible layout with StgInd
- case IND_OLDGEN_PERM:
- // follow indirections
- p = ((StgInd *)p)->indirectee;
- continue;
-
- case EVACUATED:
- // alive!
- return ((StgEvacuated *)p)->evacuee;
-
- case TSO:
- if (((StgTSO *)p)->what_next == ThreadRelocated) {
- p = (StgClosure *)((StgTSO *)p)->link;
- continue;
- }
- return NULL;
-
- default:
- // dead.
- return NULL;
+ gct->no_work++;
+#if defined(THREADED_RTS)
+ yieldThread();
+#endif
+
+ return rtsFalse;
+}
+
+static void
+scavenge_until_all_done (void)
+{
+ nat r;
+
+
+loop:
+ traceEventGcWork(&capabilities[gct->thread_index]);
+
+#if defined(THREADED_RTS)
+ if (n_gc_threads > 1) {
+ scavenge_loop();
+ } else {
+ scavenge_loop1();
}
- }
+#else
+ scavenge_loop();
+#endif
+
+ // scavenge_loop() only exits when there's no work to do
+ r = dec_running();
+
+ traceEventGcIdle(&capabilities[gct->thread_index]);
+
+ 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.
+ }
+
+ traceEventGcDone(&capabilities[gct->thread_index]);
+}
+
+#if defined(THREADED_RTS)
+
+void
+gcWorkerThread (Capability *cap)
+{
+ 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();
+
+ // 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);
+#endif
+
+ // Every thread evacuates some roots.
+ gct->evac_gen = 0;
+ markSomeCapabilities(mark_root, gct, gct->thread_index, n_gc_threads,
+ rtsTrue/*prune sparks*/);
+ scavenge_capability_mut_lists(&capabilities[gct->thread_index]);
+
+ scavenge_until_all_done();
+
+#ifdef USE_PAPI
+ // 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);
+
+ SET_GCT(saved_gct);
+}
+
+#endif
+
+#if defined(THREADED_RTS)
+
+void
+waitForGcThreads (Capability *cap USED_IF_THREADS)
+{
+ nat n_threads = RtsFlags.ParFlags.nNodes;
+ 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 // THREADED_RTS
+
+static void
+start_gc_threads (void)
+{
+#if defined(THREADED_RTS)
+ gc_running_threads = 0;
+#endif
}
static void
-mark_root(StgClosure **root)
+wakeup_gc_threads (nat n_threads USED_IF_THREADS, nat me USED_IF_THREADS)
{
- *root = evacuate(*root);
+#if defined(THREADED_RTS)
+ nat i;
+ for (i=0; i < n_threads; i++) {
+ if (i == me) continue;
+ inc_running();
+ debugTrace(DEBUG_gc, "waking up gc thread %d", i);
+ 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
+}
+
+// After GC is complete, we must wait for all GC threads to enter the
+// 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, nat me USED_IF_THREADS)
+{
+#if defined(THREADED_RTS)
+ nat i;
+ for (i=0; i < n_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)
+{
+ nat n_threads = RtsFlags.ParFlags.nNodes;
+ 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)
+{
+ nat t, i;
+ gen_workspace *ws;
+ generation *gen;
+ bdescr *bd;
+
+ // 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().
+ if (g != 0) {
+ freeChain(generations[g].mut_list);
+ generations[g].mut_list = allocBlock();
+ for (i = 0; i < n_capabilities; i++) {
+ freeChain(capabilities[i].mut_lists[g]);
+ capabilities[i].mut_lists[g] = allocBlock();
+ }
+ }
+
+ 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.
+ gen->scavenged_large_objects = NULL;
+ gen->n_scavenged_large_blocks = 0;
+
+ // 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;
+ }
+
+ // 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;
+ }
+ }
+ }
+ }
+
+ // 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++) {
+ ws = &gc_threads[t]->gens[g];
+
+ ws->todo_large_objects = NULL;
+
+ 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;
+ ASSERT(looksEmptyWSDeque(ws->todo_q));
+ alloc_todo_block(ws,0);
+
+ ws->todo_overflow = NULL;
+ ws->n_todo_overflow = 0;
+
+ ws->scavd_list = NULL;
+ ws->n_scavd_blocks = 0;
+ }
+}
+
+
+/* ----------------------------------------------------------------------------
+ Initialise a generation that is *not* to be collected
+ ------------------------------------------------------------------------- */
+
+static void
+init_uncollected_gen (nat g, nat threads)
+{
+ nat t, n;
+ gen_workspace *ws;
+ generation *gen;
+ bdescr *bd;
+
+ // 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.
+ generations[g].saved_mut_list = generations[g].mut_list;
+ generations[g].mut_list = allocBlock();
+ for (n = 0; n < n_capabilities; n++) {
+ capabilities[n].saved_mut_lists[g] = capabilities[n].mut_lists[g];
+ capabilities[n].mut_lists[g] = allocBlock();
+ }
+
+ gen = &generations[g];
+
+ gen->scavenged_large_objects = NULL;
+ gen->n_scavenged_large_blocks = 0;
+
+ for (t = 0; t < threads; t++) {
+ ws = &gc_threads[t]->gens[g];
+
+ ASSERT(looksEmptyWSDeque(ws->todo_q));
+ ws->todo_large_objects = NULL;
+
+ ws->part_list = NULL;
+ ws->n_part_blocks = 0;
+
+ ws->scavd_list = NULL;
+ ws->n_scavd_blocks = 0;
+
+ // 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 (gen->blocks && isPartiallyFull(gen->blocks))
+ {
+ ws->todo_bd = gen->blocks;
+ ws->todo_free = ws->todo_bd->free;
+ ws->todo_lim = ws->todo_bd->start + BLOCK_SIZE_W;
+ gen->blocks = gen->blocks->link;
+ gen->n_blocks -= 1;
+ gen->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);
+ }
+ }
+
+ // deal out any more partial blocks to the threads' part_lists
+ t = 0;
+ while (gen->blocks && isPartiallyFull(gen->blocks))
+ {
+ bd = gen->blocks;
+ gen->blocks = bd->link;
+ ws = &gc_threads[t]->gens[g];
+ bd->link = ws->part_list;
+ ws->part_list = bd;
+ ws->n_part_blocks += 1;
+ bd->u.scan = bd->free;
+ gen->n_blocks -= 1;
+ gen->n_words -= bd->free - bd->start;
+ t++;
+ if (t == n_gc_threads) t = 0;
+ }
+}
+
+/* -----------------------------------------------------------------------------
+ Initialise a gc_thread before GC
+ -------------------------------------------------------------------------- */
+
+static void
+init_gc_thread (gc_thread *t)
+{
+ t->static_objects = END_OF_STATIC_LIST;
+ t->scavenged_static_objects = END_OF_STATIC_LIST;
+ t->scan_bd = NULL;
+ t->mut_lists = capabilities[t->thread_index].mut_lists;
+ t->evac_gen = 0;
+ t->failed_to_evac = rtsFalse;
+ t->eager_promotion = rtsTrue;
+ t->thunk_selector_depth = 0;
+ t->copied = 0;
+ t->scanned = 0;
+ t->any_work = 0;
+ t->no_work = 0;
+ t->scav_find_work = 0;
+}
+
+/* -----------------------------------------------------------------------------
+ Function we pass to evacuate roots.
+ -------------------------------------------------------------------------- */
+
+static void
+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,
+ // so we need to save and restore it here. NB. only call
+ // mark_root() from the main GC thread, otherwise gct will be
+ // incorrect.
+ gc_thread *saved_gct;
+ saved_gct = gct;
+ SET_GCT(user);
+
+ evacuate(root);
+
+ SET_GCT(saved_gct);
}
/* -----------------------------------------------------------------------------
}
}
-/* -----------------------------------------------------------------------------
- Reverting CAFs
- -------------------------------------------------------------------------- */
+/* ----------------------------------------------------------------------------
+ Reset the sizes of the older generations when we do a major
+ collection.
+
+ CURRENT STRATEGY: make all generations except zero the same size.
+ We have to stay within the maximum heap size, and leave a certain
+ percentage of the maximum heap size available to allocate into.
+ ------------------------------------------------------------------------- */
-void
-revertCAFs( void )
+static void
+resize_generations (void)
{
- StgIndStatic *c;
+ nat g;
- for (c = (StgIndStatic *)revertible_caf_list; c != NULL;
- c = (StgIndStatic *)c->static_link)
- {
- SET_INFO(c, c->saved_info);
- c->saved_info = NULL;
- // could, but not necessary: c->static_link = NULL;
+ if (major_gc && RtsFlags.GcFlags.generations > 1) {
+ nat live, size, min_alloc, words;
+ nat max = RtsFlags.GcFlags.maxHeapSize;
+ nat gens = RtsFlags.GcFlags.generations;
+
+ // live in the oldest generations
+ 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->n_blocks >
+ (RtsFlags.GcFlags.compactThreshold * max) / 100))) {
+ oldest_gen->mark = 1;
+ oldest_gen->compact = 1;
+// debugBelch("compaction: on\n", live);
+ } else {
+ 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
+ // to double the space required to collect the old generation.
+ if (max != 0) {
+
+ // this test is necessary to ensure that the calculations
+ // below don't have any negative results - we're working
+ // with unsigned values here.
+ if (max < min_alloc) {
+ heapOverflow();
+ }
+
+ if (oldest_gen->compact) {
+ if ( (size + (size - 1) * (gens - 2) * 2) + min_alloc > max ) {
+ size = (max - min_alloc) / ((gens - 1) * 2 - 1);
+ }
+ } else {
+ if ( (size * (gens - 1) * 2) + min_alloc > max ) {
+ size = (max - min_alloc) / ((gens - 1) * 2);
+ }
+ }
+
+ if (size < live) {
+ heapOverflow();
+ }
+ }
+
+#if 0
+ debugBelch("live: %d, min_alloc: %d, size : %d, max = %d\n", live,
+ min_alloc, size, max);
+#endif
+
+ for (g = 0; g < gens; g++) {
+ generations[g].max_blocks = size;
+ }
}
- revertible_caf_list = NULL;
}
-void
-markCAFs( evac_fn evac )
+/* -----------------------------------------------------------------------------
+ Calculate the new size of the nursery, and resize it.
+ -------------------------------------------------------------------------- */
+
+static void
+resize_nursery (void)
{
- StgIndStatic *c;
+ lnat min_nursery = RtsFlags.GcFlags.minAllocAreaSize * n_capabilities;
- for (c = (StgIndStatic *)caf_list; c != NULL;
- c = (StgIndStatic *)c->static_link)
- {
- evac(&c->indirectee);
+ if (RtsFlags.GcFlags.generations == 1)
+ { // Two-space collector:
+ nat blocks;
+
+ /* set up a new nursery. Allocate a nursery size based on a
+ * function of the amount of live data (by default a factor of 2)
+ * Use the blocks from the old nursery if possible, freeing up any
+ * left over blocks.
+ *
+ * If we get near the maximum heap size, then adjust our nursery
+ * size accordingly. If the nursery is the same size as the live
+ * data (L), then we need 3L bytes. We can reduce the size of the
+ * nursery to bring the required memory down near 2L bytes.
+ *
+ * A normal 2-space collector would need 4L bytes to give the same
+ * performance we get from 3L bytes, reducing to the same
+ * performance at 2L bytes.
+ */
+ blocks = generations[0].n_blocks;
+
+ if ( RtsFlags.GcFlags.maxHeapSize != 0 &&
+ blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
+ RtsFlags.GcFlags.maxHeapSize )
+ {
+ long adjusted_blocks; // signed on purpose
+ int pc_free;
+
+ adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks);
+
+ debugTrace(DEBUG_gc, "near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld",
+ RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks);
+
+ pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize;
+ if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even * be < 0 */
+ {
+ heapOverflow();
+ }
+ blocks = adjusted_blocks;
+ }
+ else
+ {
+ blocks *= RtsFlags.GcFlags.oldGenFactor;
+ if (blocks < min_nursery)
+ {
+ blocks = min_nursery;
+ }
+ }
+ resizeNurseries(blocks);
}
- for (c = (StgIndStatic *)revertible_caf_list; c != NULL;
- c = (StgIndStatic *)c->static_link)
+ else // Generational collector
{
- evac(&c->indirectee);
+ /*
+ * If the user has given us a suggested heap size, adjust our
+ * allocation area to make best use of the memory available.
+ */
+ if (RtsFlags.GcFlags.heapSizeSuggestion)
+ {
+ long blocks;
+ 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 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
+ * a small adjustment for estimated slop at the end of a block
+ * (- 10 words).
+ */
+ if (N == 0)
+ {
+ g0_pcnt_kept = ((copied / (BLOCK_SIZE_W - 10)) * 100)
+ / countNurseryBlocks();
+ }
+
+ /* Estimate a size for the allocation area based on the
+ * information available. We might end up going slightly under
+ * or over the suggested heap size, but we should be pretty
+ * close on average.
+ *
+ * Formula: suggested - needed
+ * ----------------------------
+ * 1 + g0_pcnt_kept/100
+ *
+ * where 'needed' is the amount of memory needed at the next
+ * collection for collecting all gens except g0.
+ */
+ blocks =
+ (((long)RtsFlags.GcFlags.heapSizeSuggestion - (long)needed) * 100) /
+ (100 + (long)g0_pcnt_kept);
+
+ if (blocks < (long)min_nursery) {
+ blocks = min_nursery;
+ }
+
+ resizeNurseries((nat)blocks);
+ }
+ else
+ {
+ // we might have added extra large blocks to the nursery, so
+ // resize back to minAllocAreaSize again.
+ resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize);
+ }
}
}
debugTrace(DEBUG_gccafs, "%d CAFs live", i);
}
#endif
-
-/* -----------------------------------------------------------------------------
- * Debugging
- * -------------------------------------------------------------------------- */
-
-#if DEBUG
-void
-printMutableList(generation *gen)
-{
- bdescr *bd;
- StgPtr p;
-
- debugBelch("mutable list %p: ", gen->mut_list);
-
- for (bd = gen->mut_list; bd != NULL; bd = bd->link) {
- for (p = bd->start; p < bd->free; p++) {
- debugBelch("%p (%s), ", (void *)*p, info_type((StgClosure *)*p));
- }
- }
- debugBelch("\n");
-}
-#endif /* DEBUG */
projects / ghc-hetmet.git / blobdiff