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6818524: G1: use ergonomic resizing of PLABs

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Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.

Reviewed-by: johnc, ysr
This commit is contained in:
Brandon Mitchell 2012-08-06 12:20:14 -07:00 • committed by John Cuthbertson
parent 82446583c4
commit 3234f913bb
8 changed files with 63 additions and 27 deletions
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39
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp
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@ -33,7 +33,7 @@
#include "gc_implementation/g1/heapRegionSeq.hpp"
#include "gc_implementation/g1/heapRegionSets.hpp"
#include "gc_implementation/shared/hSpaceCounters.hpp"
#include "gc_implementation/parNew/parGCAllocBuffer.hpp"
#include "gc_implementation/shared/parGCAllocBuffer.hpp"
#include "memory/barrierSet.hpp"
#include "memory/memRegion.hpp"
#include "memory/sharedHeap.hpp"
@ -278,10 +278,33 @@ private:
// survivor objects.
SurvivorGCAllocRegion _survivor_gc_alloc_region;
// PLAB sizing policy for survivors.
PLABStats _survivor_plab_stats;
// Alloc region used to satisfy allocation requests by the GC for
// old objects.
OldGCAllocRegion _old_gc_alloc_region;
// PLAB sizing policy for tenured objects.
PLABStats _old_plab_stats;
PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
PLABStats* stats = NULL;
switch (purpose) {
case GCAllocForSurvived:
stats = &_survivor_plab_stats;
break;
case GCAllocForTenured:
stats = &_old_plab_stats;
break;
default:
assert(false, "unrecognized GCAllocPurpose");
}
return stats;
}
// The last old region we allocated to during the last GC.
// Typically, it is not full so we should re-use it during the next GC.
HeapRegion* _retained_old_gc_alloc_region;
@ -314,7 +337,7 @@ private:
G1MonitoringSupport* _g1mm;
// Determines PLAB size for a particular allocation purpose.
static size_t desired_plab_sz(GCAllocPurpose purpose);
size_t desired_plab_sz(GCAllocPurpose purpose);
// Outside of GC pauses, the number of bytes used in all regions other
// than the current allocation region.
@ -1811,19 +1834,19 @@ public:
}
HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
HeapWord* obj = NULL;
size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
assert(gclab_word_size == alloc_buf->word_sz(),
"dynamic resizing is not supported");
add_to_alloc_buffer_waste(alloc_buf->words_remaining());
alloc_buf->retire(false, false);
alloc_buf->flush_stats_and_retire(_g1h->stats_for_purpose(purpose),
false /* end_of_gc */,
false /* retain */);
HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
if (buf == NULL) return NULL; // Let caller handle allocation failure.
// Otherwise.
alloc_buf->set_word_size(gclab_word_size);
alloc_buf->set_buf(buf);
obj = alloc_buf->allocate(word_sz);
@ -1908,7 +1931,9 @@ public:
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
size_t waste = _alloc_buffers[ap]->words_remaining();
add_to_alloc_buffer_waste(waste);
_alloc_buffers[ap]->retire(true, false);
_alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
true /* end_of_gc */,
false /* retain */);
}
}