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Tweak compaction candidate selection to avoid keeping page with low occupancy around.

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Increase slots buffer chain length to 15 to make compaction more aggressive and usefull.

Pass gc and collector selection reasons to GCTracer to allow more meaningull --gc-trace.

Print fragmentation of spaces that we do not compact.

R=erik.corry@gmail.com

Review URL: https://chromiumcodereview.appspot.com/9323007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10601 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
vegorov@chromium.org 2012-02-03 14:16:40 +00:00
parent b34e202b20
commit a7b0481b6d
15 changed files with 273 additions and 103 deletions
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2
src/api.cc
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@ -4077,7 +4077,7 @@ bool v8::V8::IdleNotification(int hint) {
void v8::V8::LowMemoryNotification() {
i::Isolate* isolate = i::Isolate::Current();
if (isolate == NULL || !isolate->IsInitialized()) return;
isolate->heap()->CollectAllAvailableGarbage();
isolate->heap()->CollectAllAvailableGarbage("low memory notification");
}

11
src/debug.cc
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@ -1904,7 +1904,8 @@ void Debug::PrepareForBreakPoints() {
{
// We are going to iterate heap to find all functions without
// debug break slots.
isolate_->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
isolate_->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"preparing for breakpoints");
// Ensure no GC in this scope as we are going to use gc_metadata
// field in the Code object to mark active functions.
@ -2230,8 +2231,9 @@ void Debug::CreateScriptCache() {
// rid of all the cached script wrappers and the second gets rid of the
// scripts which are no longer referenced. The second also sweeps precisely,
// which saves us doing yet another GC to make the heap iterable.
heap->CollectAllGarbage(Heap::kNoGCFlags);
heap->CollectAllGarbage(Heap::kMakeHeapIterableMask);
heap->CollectAllGarbage(Heap::kNoGCFlags, "Debug::CreateScriptCache");
heap->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"Debug::CreateScriptCache");
ASSERT(script_cache_ == NULL);
script_cache_ = new ScriptCache();
@ -2281,7 +2283,8 @@ Handle<FixedArray> Debug::GetLoadedScripts() {
// Perform GC to get unreferenced scripts evicted from the cache before
// returning the content.
isolate_->heap()->CollectAllGarbage(Heap::kNoGCFlags);
isolate_->heap()->CollectAllGarbage(Heap::kNoGCFlags,
"Debug::GetLoadedScripts");
// Get the scripts from the cache.
return script_cache_->GetScripts();

2
src/execution.cc
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@ -877,7 +877,7 @@ MaybeObject* Execution::HandleStackGuardInterrupt() {
StackGuard* stack_guard = isolate->stack_guard();
if (stack_guard->IsGCRequest()) {
isolate->heap()->CollectAllGarbage(false);
isolate->heap()->CollectAllGarbage(false, "StackGuard GC request");
stack_guard->Continue(GC_REQUEST);
}

2
src/extensions/gc-extension.cc
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@ -40,7 +40,7 @@ v8::Handle<v8::FunctionTemplate> GCExtension::GetNativeFunction(
v8::Handle<v8::Value> GCExtension::GC(const v8::Arguments& args) {
HEAP->CollectAllGarbage(Heap::kNoGCFlags);
HEAP->CollectAllGarbage(Heap::kNoGCFlags, "gc extension");
return v8::Undefined();
}

13
src/heap-inl.h
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@ -438,8 +438,10 @@ void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
}
bool Heap::CollectGarbage(AllocationSpace space) {
return CollectGarbage(space, SelectGarbageCollector(space));
bool Heap::CollectGarbage(AllocationSpace space, const char* gc_reason) {
const char* collector_reason = NULL;
GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);
return CollectGarbage(space, collector, gc_reason, collector_reason);
}
@ -474,7 +476,7 @@ int Heap::AdjustAmountOfExternalAllocatedMemory(int change_in_bytes) {
amount_of_external_allocated_memory_ -
amount_of_external_allocated_memory_at_last_global_gc_;
if (amount_since_last_global_gc > external_allocation_limit_) {
CollectAllGarbage(kNoGCFlags);
CollectAllGarbage(kNoGCFlags, "external memory allocation limit reached");
}
} else {
// Avoid underflow.
@ -523,7 +525,8 @@ Isolate* Heap::isolate() {
} \
if (!__maybe_object__->IsRetryAfterGC()) RETURN_EMPTY; \
ISOLATE->heap()->CollectGarbage(Failure::cast(__maybe_object__)-> \
allocation_space()); \
allocation_space(), \
"allocation failure"); \
__maybe_object__ = FUNCTION_CALL; \
if (__maybe_object__->ToObject(&__object__)) RETURN_VALUE; \
if (__maybe_object__->IsOutOfMemory()) { \
@ -531,7 +534,7 @@ Isolate* Heap::isolate() {
} \
if (!__maybe_object__->IsRetryAfterGC()) RETURN_EMPTY; \
ISOLATE->counters()->gc_last_resort_from_handles()->Increment(); \
ISOLATE->heap()->CollectAllAvailableGarbage(); \
ISOLATE->heap()->CollectAllAvailableGarbage("last resort gc"); \
{ \
AlwaysAllocateScope __scope__; \
__maybe_object__ = FUNCTION_CALL; \

83
src/heap.cc
View File

@ -236,16 +236,19 @@ int Heap::GcSafeSizeOfOldObject(HeapObject* object) {
}
GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space) {
GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space,
const char** reason) {
// Is global GC requested?
if (space != NEW_SPACE || FLAG_gc_global) {
isolate_->counters()->gc_compactor_caused_by_request()->Increment();
*reason = "GC in old space requested";
return MARK_COMPACTOR;
}
// Is enough data promoted to justify a global GC?
if (OldGenerationPromotionLimitReached()) {
isolate_->counters()->gc_compactor_caused_by_promoted_data()->Increment();
*reason = "promotion limit reached";
return MARK_COMPACTOR;
}
@ -253,6 +256,7 @@ GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space) {
if (old_gen_exhausted_) {
isolate_->counters()->
gc_compactor_caused_by_oldspace_exhaustion()->Increment();
*reason = "old generations exhausted";
return MARK_COMPACTOR;
}
@ -268,10 +272,12 @@ GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space) {
if (isolate_->memory_allocator()->MaxAvailable() <= new_space_.Size()) {
isolate_->counters()->
gc_compactor_caused_by_oldspace_exhaustion()->Increment();
*reason = "scavenge might not succeed";
return MARK_COMPACTOR;
}
// Default
*reason = NULL;
return SCAVENGER;
}
@ -431,17 +437,17 @@ void Heap::GarbageCollectionEpilogue() {
}
void Heap::CollectAllGarbage(int flags) {
void Heap::CollectAllGarbage(int flags, const char* gc_reason) {
// Since we are ignoring the return value, the exact choice of space does
// not matter, so long as we do not specify NEW_SPACE, which would not
// cause a full GC.
mark_compact_collector_.SetFlags(flags);
CollectGarbage(OLD_POINTER_SPACE);
CollectGarbage(OLD_POINTER_SPACE, gc_reason);
mark_compact_collector_.SetFlags(kNoGCFlags);
}
void Heap::CollectAllAvailableGarbage() {
void Heap::CollectAllAvailableGarbage(const char* gc_reason) {
// Since we are ignoring the return value, the exact choice of space does
// not matter, so long as we do not specify NEW_SPACE, which would not
// cause a full GC.
@ -453,11 +459,12 @@ void Heap::CollectAllAvailableGarbage() {
// Note: as weak callbacks can execute arbitrary code, we cannot
// hope that eventually there will be no weak callbacks invocations.
// Therefore stop recollecting after several attempts.
mark_compact_collector()->SetFlags(kMakeHeapIterableMask);
mark_compact_collector()->SetFlags(kMakeHeapIterableMask |
kReduceMemoryFootprintMask);
isolate_->compilation_cache()->Clear();
const int kMaxNumberOfAttempts = 7;
for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
if (!CollectGarbage(OLD_POINTER_SPACE, MARK_COMPACTOR)) {
if (!CollectGarbage(OLD_POINTER_SPACE, MARK_COMPACTOR, gc_reason, NULL)) {
break;
}
}
@ -469,7 +476,10 @@ void Heap::CollectAllAvailableGarbage() {
}
bool Heap::CollectGarbage(AllocationSpace space, GarbageCollector collector) {
bool Heap::CollectGarbage(AllocationSpace space,
GarbageCollector collector,
const char* gc_reason,
const char* collector_reason) {
// The VM is in the GC state until exiting this function.
VMState state(isolate_, GC);
@ -497,11 +507,12 @@ bool Heap::CollectGarbage(AllocationSpace space, GarbageCollector collector) {
PrintF("[IncrementalMarking] Delaying MarkSweep.\n");
}
collector = SCAVENGER;
collector_reason = "incremental marking delaying mark-sweep";
}
bool next_gc_likely_to_collect_more = false;
{ GCTracer tracer(this);
{ GCTracer tracer(this, gc_reason, collector_reason);
GarbageCollectionPrologue();
// The GC count was incremented in the prologue. Tell the tracer about
// it.
@ -533,7 +544,7 @@ bool Heap::CollectGarbage(AllocationSpace space, GarbageCollector collector) {
void Heap::PerformScavenge() {
GCTracer tracer(this);
GCTracer tracer(this, NULL, NULL);
if (incremental_marking()->IsStopped()) {
PerformGarbageCollection(SCAVENGER, &tracer);
} else {
@ -588,27 +599,33 @@ void Heap::ReserveSpace(
while (gc_performed && counter++ < kThreshold) {
gc_performed = false;
if (!new_space->ReserveSpace(new_space_size)) {
Heap::CollectGarbage(NEW_SPACE);
Heap::CollectGarbage(NEW_SPACE,
"failed to reserve space in the new space");
gc_performed = true;
}
if (!old_pointer_space->ReserveSpace(pointer_space_size)) {
Heap::CollectGarbage(OLD_POINTER_SPACE);
Heap::CollectGarbage(OLD_POINTER_SPACE,
"failed to reserve space in the old pointer space");
gc_performed = true;
}
if (!(old_data_space->ReserveSpace(data_space_size))) {
Heap::CollectGarbage(OLD_DATA_SPACE);
Heap::CollectGarbage(OLD_DATA_SPACE,
"failed to reserve space in the old data space");
gc_performed = true;
}
if (!(code_space->ReserveSpace(code_space_size))) {
Heap::CollectGarbage(CODE_SPACE);
Heap::CollectGarbage(CODE_SPACE,
"failed to reserve space in the code space");
gc_performed = true;
}
if (!(map_space->ReserveSpace(map_space_size))) {
Heap::CollectGarbage(MAP_SPACE);
Heap::CollectGarbage(MAP_SPACE,
"failed to reserve space in the map space");
gc_performed = true;
}
if (!(cell_space->ReserveSpace(cell_space_size))) {
Heap::CollectGarbage(CELL_SPACE);
Heap::CollectGarbage(CELL_SPACE,
"failed to reserve space in the cell space");
gc_performed = true;
}
// We add a slack-factor of 2 in order to have space for a series of
@ -620,7 +637,8 @@ void Heap::ReserveSpace(
large_object_size += cell_space_size + map_space_size + code_space_size +
data_space_size + pointer_space_size;
if (!(lo_space->ReserveSpace(large_object_size))) {
Heap::CollectGarbage(LO_SPACE);
Heap::CollectGarbage(LO_SPACE,
"failed to reserve space in the large object space");
gc_performed = true;
}
}
@ -4742,7 +4760,7 @@ bool Heap::IsHeapIterable() {
void Heap::EnsureHeapIsIterable() {
ASSERT(IsAllocationAllowed());
if (!IsHeapIterable()) {
CollectAllGarbage(kMakeHeapIterableMask);
CollectAllGarbage(kMakeHeapIterableMask, "Heap::EnsureHeapIsIterable");
}
ASSERT(IsHeapIterable());
}
@ -4812,7 +4830,7 @@ bool Heap::IdleNotification(int hint) {
isolate_->compilation_cache()->Clear();
uncommit = true;
}
CollectAllGarbage(kNoGCFlags);
CollectAllGarbage(kNoGCFlags, "idle notification: finalize incremental");
gc_count_at_last_idle_gc_ = gc_count_;
if (uncommit) {
new_space_.Shrink();
@ -4853,9 +4871,10 @@ bool Heap::IdleGlobalGC() {
if (number_idle_notifications_ == kIdlesBeforeScavenge) {
if (contexts_disposed_ > 0) {
HistogramTimerScope scope(isolate_->counters()->gc_context());
CollectAllGarbage(kNoGCFlags);
CollectAllGarbage(kReduceMemoryFootprintMask,
"idle notification: contexts disposed");
} else {
CollectGarbage(NEW_SPACE);
CollectGarbage(NEW_SPACE, "idle notification");
}
new_space_.Shrink();
last_idle_notification_gc_count_ = gc_count_;
@ -4865,12 +4884,12 @@ bool Heap::IdleGlobalGC() {
// generated code for cached functions.
isolate_->compilation_cache()->Clear();
CollectAllGarbage(kNoGCFlags);
CollectAllGarbage(kReduceMemoryFootprintMask, "idle notification");
new_space_.Shrink();
last_idle_notification_gc_count_ = gc_count_;
} else if (number_idle_notifications_ == kIdlesBeforeMarkCompact) {
CollectAllGarbage(kNoGCFlags);
CollectAllGarbage(kReduceMemoryFootprintMask, "idle notification");
new_space_.Shrink();
last_idle_notification_gc_count_ = gc_count_;
number_idle_notifications_ = 0;
@ -4880,7 +4899,8 @@ bool Heap::IdleGlobalGC() {
contexts_disposed_ = 0;
} else {
HistogramTimerScope scope(isolate_->counters()->gc_context());
CollectAllGarbage(kNoGCFlags);
CollectAllGarbage(kReduceMemoryFootprintMask,
"idle notification: contexts disposed");
last_idle_notification_gc_count_ = gc_count_;
}
// If this is the first idle notification, we reset the
@ -6511,7 +6531,9 @@ static intptr_t CountTotalHolesSize() {
}
GCTracer::GCTracer(Heap* heap)
GCTracer::GCTracer(Heap* heap,
const char* gc_reason,
const char* collector_reason)
: start_time_(0.0),
start_object_size_(0),
start_memory_size_(0),
@ -6520,7 +6542,9 @@ GCTracer::GCTracer(Heap* heap)
allocated_since_last_gc_(0),
spent_in_mutator_(0),
promoted_objects_size_(0),
heap_(heap) {
heap_(heap),
gc_reason_(gc_reason),
collector_reason_(collector_reason) {
if (!FLAG_trace_gc && !FLAG_print_cumulative_gc_stat) return;
start_time_ = OS::TimeCurrentMillis();
start_object_size_ = heap_->SizeOfObjects();
@ -6599,6 +6623,15 @@ GCTracer::~GCTracer() {
longest_step_);
}
}
if (gc_reason_ != NULL) {
PrintF(" [%s]", gc_reason_);
}
if (collector_reason_ != NULL) {
PrintF(" [%s]", collector_reason_);
}
PrintF(".\n");
} else {
PrintF("pause=%d ", time);

23
src/heap.h
View File

@ -1025,23 +1025,28 @@ class Heap {
// Performs garbage collection operation.
// Returns whether there is a chance that another major GC could
// collect more garbage.
bool CollectGarbage(AllocationSpace space, GarbageCollector collector);
bool CollectGarbage(AllocationSpace space,
GarbageCollector collector,
const char* gc_reason,
const char* collector_reason);
// Performs garbage collection operation.
// Returns whether there is a chance that another major GC could
// collect more garbage.
inline bool CollectGarbage(AllocationSpace space);
inline bool CollectGarbage(AllocationSpace space,
const char* gc_reason = NULL);
static const int kNoGCFlags = 0;
static const int kMakeHeapIterableMask = 1;
static const int kReduceMemoryFootprintMask = 2;
// Performs a full garbage collection. If (flags & kMakeHeapIterableMask) is
// non-zero, then the slower precise sweeper is used, which leaves the heap
// in a state where we can iterate over the heap visiting all objects.
void CollectAllGarbage(int flags);
void CollectAllGarbage(int flags, const char* gc_reason = NULL);
// Last hope GC, should try to squeeze as much as possible.
void CollectAllAvailableGarbage();
void CollectAllAvailableGarbage(const char* gc_reason = NULL);
// Check whether the heap is currently iterable.
bool IsHeapIterable();
@ -1741,7 +1746,8 @@ class Heap {
}
// Checks whether a global GC is necessary
GarbageCollector SelectGarbageCollector(AllocationSpace space);
GarbageCollector SelectGarbageCollector(AllocationSpace space,
const char** reason);
// Performs garbage collection
// Returns whether there is a chance another major GC could
@ -2364,7 +2370,9 @@ class GCTracer BASE_EMBEDDED {
double start_time_;
};
explicit GCTracer(Heap* heap);
explicit GCTracer(Heap* heap,
const char* gc_reason,
const char* collector_reason);
~GCTracer();
// Sets the collector.
@ -2432,6 +2440,9 @@ class GCTracer BASE_EMBEDDED {
double steps_took_since_last_gc_;
Heap* heap_;
const char* gc_reason_;
const char* collector_reason_;
};

9
src/log.cc
View File

@ -1521,7 +1521,8 @@ void Logger::LowLevelLogWriteBytes(const char* bytes, int size) {
void Logger::LogCodeObjects() {
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask);
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"Logger::LogCodeObjects");
HeapIterator iterator;
AssertNoAllocation no_alloc;
for (HeapObject* obj = iterator.next(); obj != NULL; obj = iterator.next()) {
@ -1576,7 +1577,8 @@ void Logger::LogExistingFunction(Handle<SharedFunctionInfo> shared,
void Logger::LogCompiledFunctions() {
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask);
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"Logger::LogCompiledFunctions");
HandleScope scope;
const int compiled_funcs_count = EnumerateCompiledFunctions(NULL, NULL);
ScopedVector< Handle<SharedFunctionInfo> > sfis(compiled_funcs_count);
@ -1595,7 +1597,8 @@ void Logger::LogCompiledFunctions() {
void Logger::LogAccessorCallbacks() {
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask);
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"Logger::LogAccessorCallbacks");
HeapIterator iterator;
AssertNoAllocation no_alloc;
for (HeapObject* obj = iterator.next(); obj != NULL; obj = iterator.next()) {

1
src/mark-compact-inl.h
View File

@ -46,6 +46,7 @@ MarkBit Marking::MarkBitFrom(Address addr) {
void MarkCompactCollector::SetFlags(int flags) {
sweep_precisely_ = ((flags & Heap::kMakeHeapIterableMask) != 0);
reduce_memory_footprint_ = ((flags & Heap::kReduceMemoryFootprintMask) != 0);
}

153
src/mark-compact.cc
View File

@ -230,6 +230,18 @@ void MarkCompactCollector::AddEvacuationCandidate(Page* p) {
}
static void TraceFragmentation(PagedSpace* space) {
int number_of_pages = space->CountTotalPages();
intptr_t reserved = (number_of_pages * Page::kObjectAreaSize);
intptr_t free = reserved - space->SizeOfObjects();
PrintF("[%s]: %d pages, %d (%.1f%%) free\n",
AllocationSpaceName(space->identity()),
number_of_pages,
static_cast<int>(free),
static_cast<double>(free) * 100 / reserved);
}
bool MarkCompactCollector::StartCompaction() {
if (!compacting_) {
ASSERT(evacuation_candidates_.length() == 0);
@ -239,6 +251,13 @@ bool MarkCompactCollector::StartCompaction() {
if (FLAG_compact_code_space) {
CollectEvacuationCandidates(heap()->code_space());
} else if (FLAG_trace_fragmentation) {
TraceFragmentation(heap()->code_space());
}
if (FLAG_trace_fragmentation) {
TraceFragmentation(heap()->map_space());
TraceFragmentation(heap()->cell_space());
}
heap()->old_pointer_space()->EvictEvacuationCandidatesFromFreeLists();
@ -414,6 +433,65 @@ const char* AllocationSpaceName(AllocationSpace space) {
}
// Returns zero for pages that have so little fragmentation that it is not
// worth defragmenting them. Otherwise a positive integer that gives an
// estimate of fragmentation on an arbitrary scale.
static int FreeListFragmentation(PagedSpace* space, Page* p) {
// If page was not swept then there are no free list items on it.
if (!p->WasSwept()) {
if (FLAG_trace_fragmentation) {
PrintF("%p [%s]: %d bytes live (unswept)\n",
reinterpret_cast<void*>(p),
AllocationSpaceName(space->identity()),
p->LiveBytes());
}
return 0;
}
FreeList::SizeStats sizes;
space->CountFreeListItems(p, &sizes);
intptr_t ratio;
intptr_t ratio_threshold;
if (space->identity() == CODE_SPACE) {
ratio = (sizes.medium_size_ * 10 + sizes.large_size_ * 2) * 100 /
Page::kObjectAreaSize;
ratio_threshold = 10;
} else {
ratio = (sizes.small_size_ * 5 + sizes.medium_size_) * 100 /
Page::kObjectAreaSize;
ratio_threshold = 15;
}
if (FLAG_trace_fragmentation) {
PrintF("%p [%s]: %d (%.2f%%) %d (%.2f%%) %d (%.2f%%) %d (%.2f%%) %s\n",
reinterpret_cast<void*>(p),
AllocationSpaceName(space->identity()),
static_cast<int>(sizes.small_size_),
static_cast<double>(sizes.small_size_ * 100) /
Page::kObjectAreaSize,
static_cast<int>(sizes.medium_size_),
static_cast<double>(sizes.medium_size_ * 100) /
Page::kObjectAreaSize,
static_cast<int>(sizes.large_size_),
static_cast<double>(sizes.large_size_ * 100) /
Page::kObjectAreaSize,
static_cast<int>(sizes.huge_size_),
static_cast<double>(sizes.huge_size_ * 100) /
Page::kObjectAreaSize,
(ratio > ratio_threshold) ? "[fragmented]" : "");
}
if (FLAG_always_compact && sizes.Total() != Page::kObjectAreaSize) {
return 1;
}
if (ratio <= ratio_threshold) return 0; // Not fragmented.
return static_cast<int>(ratio - ratio_threshold);
}
void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
ASSERT(space->identity() == OLD_POINTER_SPACE ||
space->identity() == OLD_DATA_SPACE ||
@ -421,7 +499,6 @@ void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
int number_of_pages = space->CountTotalPages();
PageIterator it(space);
const int kMaxMaxEvacuationCandidates = 1000;
int max_evacuation_candidates = Min(
kMaxMaxEvacuationCandidates,
@ -444,22 +521,89 @@ void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
Page* page_;
};
enum CompactionMode {
COMPACT_FREE_LISTS,
REDUCE_MEMORY_FOOTPRINT
};
CompactionMode mode = COMPACT_FREE_LISTS;
intptr_t reserved = number_of_pages * Page::kObjectAreaSize;
intptr_t over_reserved = reserved - space->SizeOfObjects();
static const intptr_t kFreenessThreshold = 50;
if (over_reserved >= 2 * Page::kObjectAreaSize &&
reduce_memory_footprint_) {
mode = REDUCE_MEMORY_FOOTPRINT;
// We expect that empty pages are easier to compact so slightly bump the
// limit.
max_evacuation_candidates += 2;
if (FLAG_trace_fragmentation) {
PrintF("Estimated over reserved memory: %.1f MB (setting threshold %d)\n",
static_cast<double>(over_reserved) / MB,
kFreenessThreshold);
}
}
intptr_t estimated_release = 0;
Candidate candidates[kMaxMaxEvacuationCandidates];
int count = 0;
if (it.has_next()) it.next(); // Never compact the first page.
int fragmentation = 0;
Candidate* least = NULL;
PageIterator it(space);
if (it.has_next()) it.next(); // Never compact the first page.
while (it.has_next()) {
Page* p = it.next();
p->ClearEvacuationCandidate();
if (FLAG_stress_compaction) {
int counter = space->heap()->ms_count();
uintptr_t page_number = reinterpret_cast<uintptr_t>(p) >> kPageSizeBits;
if ((counter & 1) == (page_number & 1)) fragmentation = 1;
} else if (mode == REDUCE_MEMORY_FOOTPRINT) {
// Don't try to release too many pages.
if (estimated_release >= ((over_reserved * 3) / 4)) {
continue;
}
intptr_t free_bytes = 0;
if (!p->WasSwept()) {
free_bytes = (Page::kObjectAreaSize - p->LiveBytes());
} else {
FreeList::SizeStats sizes;
space->CountFreeListItems(p, &sizes);
free_bytes = sizes.Total();
}
int free_pct = static_cast<int>(free_bytes * 100 / Page::kObjectAreaSize);
if (free_pct >= kFreenessThreshold) {
estimated_release += Page::kObjectAreaSize +
(Page::kObjectAreaSize - free_bytes);
fragmentation = free_pct;
} else {
fragmentation = 0;
}
if (FLAG_trace_fragmentation) {
PrintF("%p [%s]: %d (%.2f%%) free %s\n",
reinterpret_cast<void*>(p),
AllocationSpaceName(space->identity()),
free_bytes,
static_cast<double>(free_bytes * 100) / Page::kObjectAreaSize,
(fragmentation > 0) ? "[fragmented]" : "");
}
} else {
fragmentation = space->Fragmentation(p);
fragmentation = FreeListFragmentation(space, p);
}
if (fragmentation != 0) {
if (count < max_evacuation_candidates) {
candidates[count++] = Candidate(fragmentation, p);
@ -479,6 +623,7 @@ void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
}
}
}
for (int i = 0; i < count; i++) {
AddEvacuationCandidate(candidates[i].page());
}
@ -3242,6 +3387,8 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
p->set_scan_on_scavenge(false);
slots_buffer_allocator_.DeallocateChain(p->slots_buffer_address());
p->ClearEvacuationCandidate();
p->ResetLiveBytes();
space->ReleasePage(p);
}
evacuation_candidates_.Rewind(0);
compacting_ = false;

4
src/mark-compact.h
View File

@ -374,7 +374,7 @@ class SlotsBuffer {
static const int kNumberOfElements = 1021;
private:
static const int kChainLengthThreshold = 6;
static const int kChainLengthThreshold = 15;
intptr_t idx_;
intptr_t chain_length_;
@ -572,6 +572,8 @@ class MarkCompactCollector {
// heap.
bool sweep_precisely_;
bool reduce_memory_footprint_;
// True if we are collecting slots to perform evacuation from evacuation
// candidates.
bool compacting_;

2
src/mksnapshot.cc
View File

@ -312,7 +312,7 @@ int main(int argc, char** argv) {
}
// If we don't do this then we end up with a stray root pointing at the
// context even after we have disposed of the context.
HEAP->CollectAllGarbage(i::Heap::kNoGCFlags);
HEAP->CollectAllGarbage(i::Heap::kNoGCFlags, "mksnapshot");
i::Object* raw_context = *(v8::Utils::OpenHandle(*context));
context.Dispose();
CppByteSink sink(argv[1]);

11
src/profile-generator.cc
View File

@ -1562,7 +1562,8 @@ void HeapSnapshotsCollection::RemoveSnapshot(HeapSnapshot* snapshot) {
Handle<HeapObject> HeapSnapshotsCollection::FindHeapObjectById(uint64_t id) {
// First perform a full GC in order to avoid dead objects.
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask);
HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"HeapSnapshotsCollection::FindHeapObjectById");
AssertNoAllocation no_allocation;
HeapObject* object = NULL;
HeapIterator iterator(HeapIterator::kFilterUnreachable);
@ -3056,8 +3057,12 @@ bool HeapSnapshotGenerator::GenerateSnapshot() {
// full GC is reachable from the root when computing dominators.
// This is not true for weakly reachable objects.
// As a temporary solution we call GC twice.
Isolate::Current()->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
Isolate::Current()->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
Isolate::Current()->heap()->CollectAllGarbage(
Heap::kMakeHeapIterableMask,
"HeapSnapshotGenerator::GenerateSnapshot");
Isolate::Current()->heap()->CollectAllGarbage(
Heap::kMakeHeapIterableMask,
"HeapSnapshotGenerator::GenerateSnapshot");
#ifdef DEBUG
Heap* debug_heap = Isolate::Current()->heap();

14
src/runtime.cc
View File

@ -12445,7 +12445,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugReferencedBy) {
ASSERT(args.length() == 3);
// First perform a full GC in order to avoid references from dead objects.
isolate->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
isolate->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"%DebugReferencedBy");
// The heap iterator reserves the right to do a GC to make the heap iterable.
// Due to the GC above we know it won't need to do that, but it seems cleaner
// to get the heap iterator constructed before we start having unprotected
@ -12536,7 +12537,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugConstructedBy) {
ASSERT(args.length() == 2);
// First perform a full GC in order to avoid dead objects.
isolate->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
isolate->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask,
"%DebugConstructedBy");
// Check parameters.
CONVERT_CHECKED(JSFunction, constructor, args[0]);
@ -12934,7 +12936,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_SetFlags) {
// Performs a GC.
// Presently, it only does a full GC.
RUNTIME_FUNCTION(MaybeObject*, Runtime_CollectGarbage) {
isolate->heap()->CollectAllGarbage(true);
isolate->heap()->CollectAllGarbage(true, "%CollectGarbage");
return isolate->heap()->undefined_value();
}
@ -13645,12 +13647,14 @@ void Runtime::PerformGC(Object* result) {
}
// Try to do a garbage collection; ignore it if it fails. The C
// entry stub will throw an out-of-memory exception in that case.
isolate->heap()->CollectGarbage(failure->allocation_space());
isolate->heap()->CollectGarbage(failure->allocation_space(),
"Runtime::PerformGC");
} else {
// Handle last resort GC and make sure to allow future allocations
// to grow the heap without causing GCs (if possible).
isolate->counters()->gc_last_resort_from_js()->Increment();
isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags);
isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
"Runtime::PerformGC");
}
}

46
src/spaces.h
View File

@ -1589,50 +1589,8 @@ class PagedSpace : public Space {
Page* FirstPage() { return anchor_.next_page(); }
Page* LastPage() { return anchor_.prev_page(); }
// Returns zero for pages that have so little fragmentation that it is not
// worth defragmenting them. Otherwise a positive integer that gives an
// estimate of fragmentation on an arbitrary scale.
int Fragmentation(Page* p) {
FreeList::SizeStats sizes;
free_list_.CountFreeListItems(p, &sizes);
intptr_t ratio;
intptr_t ratio_threshold;
if (identity() == CODE_SPACE) {
ratio = (sizes.medium_size_ * 10 + sizes.large_size_ * 2) * 100 /
Page::kObjectAreaSize;
ratio_threshold = 10;
} else {
ratio = (sizes.small_size_ * 5 + sizes.medium_size_) * 100 /
Page::kObjectAreaSize;
ratio_threshold = 15;
}
if (FLAG_trace_fragmentation) {
PrintF("%p [%d]: %d (%.2f%%) %d (%.2f%%) %d (%.2f%%) %d (%.2f%%) %s\n",
reinterpret_cast<void*>(p),
identity(),
static_cast<int>(sizes.small_size_),
static_cast<double>(sizes.small_size_ * 100) /
Page::kObjectAreaSize,
static_cast<int>(sizes.medium_size_),
static_cast<double>(sizes.medium_size_ * 100) /
Page::kObjectAreaSize,
static_cast<int>(sizes.large_size_),
static_cast<double>(sizes.large_size_ * 100) /
Page::kObjectAreaSize,
static_cast<int>(sizes.huge_size_),
static_cast<double>(sizes.huge_size_ * 100) /
Page::kObjectAreaSize,
(ratio > ratio_threshold) ? "[fragmented]" : "");
}
if (FLAG_always_compact && sizes.Total() != Page::kObjectAreaSize) {
return 1;
}
if (ratio <= ratio_threshold) return 0; // Not fragmented.
return static_cast<int>(ratio - ratio_threshold);
void CountFreeListItems(Page* p, FreeList::SizeStats* sizes) {
free_list_.CountFreeListItems(p, sizes);
}
void EvictEvacuationCandidatesFromFreeLists();