Reviewers: Vyacheslav Egorov,
Description:
Fix responsiveness of high promotion mode heuristics.
This changes the heuristics for the high promotion mode to be checked
on all GCs (including scavenges), so that changes in the applications
behavior are recognized earlier. It also fixes miscalculations in the
survival counter and rate which caused heuristics to fail completely.
[email protected]
BUG=v8:1899
Please review this at http://codereview.chromium.org/9196003/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/heap.h
M src/heap.cc
Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index
6295788f0af9a2f4d1e772143ff684362b568d75..20e37034988236b9e748109a51756149f10a166d
100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -688,12 +688,18 @@ void Heap::UpdateSurvivalRateTrend(int
start_new_space_size) {
(static_cast<double>(young_survivors_after_last_gc_) * 100) /
start_new_space_size;
- if (survival_rate > kYoungSurvivalRateThreshold) {
+ if (survival_rate > kYoungSurvivalRateHighThreshold) {
high_survival_rate_period_length_++;
} else {
high_survival_rate_period_length_ = 0;
}
+ if (survival_rate < kYoungSurvivalRateLowThreshold) {
+ low_survival_rate_period_length_++;
+ } else {
+ low_survival_rate_period_length_ = 0;
+ }
+
double survival_rate_diff = survival_rate_ - survival_rate;
if (survival_rate_diff > kYoungSurvivalRateAllowedDeviation) {
@@ -753,32 +759,6 @@ bool Heap::PerformGarbageCollection(GarbageCollector
collector,
UpdateSurvivalRateTrend(start_new_space_size);
- if (!new_space_high_promotion_mode_active_ &&
- new_space_.Capacity() == new_space_.MaximumCapacity() &&
- IsStableOrIncreasingSurvivalTrend() &&
- IsHighSurvivalRate()) {
- // Stable high survival rates even though young generation is at
- // maximum capacity indicates that most objects will be promoted.
- // To decrease scavenger pauses and final mark-sweep pauses, we
- // have to limit maximal capacity of the young generation.
- new_space_high_promotion_mode_active_ = true;
- if (FLAG_trace_gc) {
- PrintF("Limited new space size due to high promotion rate: %d
MB\n",
- new_space_.InitialCapacity() / MB);
- }
- } else if (new_space_high_promotion_mode_active_ &&
- IsDecreasingSurvivalTrend() &&
- !IsHighSurvivalRate()) {
- // Decreasing low survival rates might indicate that the above high
- // promotion mode is over and we should allow the young generation
- // to grow again.
- new_space_high_promotion_mode_active_ = false;
- if (FLAG_trace_gc) {
- PrintF("Unlimited new space size due to low promotion rate: %d
MB\n",
- new_space_.MaximumCapacity() / MB);
- }
- }
-
size_of_old_gen_at_last_old_space_gc_ = PromotedSpaceSize();
if (high_survival_rate_during_scavenges &&
@@ -808,6 +788,32 @@ bool Heap::PerformGarbageCollection(GarbageCollector
collector,
UpdateSurvivalRateTrend(start_new_space_size);
}
+ if (!new_space_high_promotion_mode_active_ &&
+ new_space_.Capacity() == new_space_.MaximumCapacity() &&
+ IsStableOrIncreasingSurvivalTrend() &&
+ IsHighSurvivalRate()) {
+ // Stable high survival rates even though young generation is at
+ // maximum capacity indicates that most objects will be promoted.
+ // To decrease scavenger pauses and final mark-sweep pauses, we
+ // have to limit maximal capacity of the young generation.
+ new_space_high_promotion_mode_active_ = true;
+ if (FLAG_trace_gc) {
+ PrintF("Limited new space size due to high promotion rate: %d MB\n",
+ new_space_.InitialCapacity() / MB);
+ }
+ } else if (new_space_high_promotion_mode_active_ &&
+ IsStableOrDecreasingSurvivalTrend() &&
+ IsLowSurvivalRate()) {
+ // Decreasing low survival rates might indicate that the above high
+ // promotion mode is over and we should allow the young generation
+ // to grow again.
+ new_space_high_promotion_mode_active_ = false;
+ if (FLAG_trace_gc) {
+ PrintF("Unlimited new space size due to low promotion rate: %d MB\n",
+ new_space_.MaximumCapacity() / MB);
+ }
+ }
+
if (new_space_high_promotion_mode_active_ &&
new_space_.Capacity() > new_space_.InitialCapacity()) {
new_space_.Shrink();
@@ -5404,12 +5410,12 @@ void Heap::RecordStats(HeapStats* stats, bool
take_snapshot) {
intptr_t Heap::PromotedSpaceSize() {
- return old_pointer_space_->Size()
- + old_data_space_->Size()
- + code_space_->Size()
- + map_space_->Size()
- + cell_space_->Size()
- + lo_space_->Size();
+ return old_pointer_space_->SizeOfObjects()
+ + old_data_space_->SizeOfObjects()
+ + code_space_->SizeOfObjects()
+ + map_space_->SizeOfObjects()
+ + cell_space_->SizeOfObjects()
+ + lo_space_->SizeOfObjects();
}
Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index
6dc9d61117d93ff34041c093db077111a2a47ef6..d47d2a58bcce88184db0f89dd6946980ad3fb375
100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1381,6 +1381,7 @@ class Heap {
void CheckNewSpaceExpansionCriteria();
inline void IncrementYoungSurvivorsCounter(int survived) {
+ ASSERT(survived >= 0);
young_survivors_after_last_gc_ = survived;
survived_since_last_expansion_ += survived;
}
@@ -1799,11 +1800,13 @@ class Heap {
enum SurvivalRateTrend { INCREASING, STABLE, DECREASING, FLUCTUATING };
- static const int kYoungSurvivalRateThreshold = 90;
+ static const int kYoungSurvivalRateHighThreshold = 90;
+ static const int kYoungSurvivalRateLowThreshold = 10;
static const int kYoungSurvivalRateAllowedDeviation = 15;
int young_survivors_after_last_gc_;
int high_survival_rate_period_length_;
+ int low_survival_rate_period_length_;
double survival_rate_;
SurvivalRateTrend previous_survival_rate_trend_;
SurvivalRateTrend survival_rate_trend_;
@@ -1836,18 +1839,28 @@ class Heap {
}
}
- bool IsIncreasingSurvivalTrend() {
- return survival_rate_trend() == INCREASING;
+ bool IsStableOrDecreasingSurvivalTrend() {
+ switch (survival_rate_trend()) {
+ case STABLE:
+ case DECREASING:
+ return true;
+ default:
+ return false;
+ }
}
- bool IsDecreasingSurvivalTrend() {
- return survival_rate_trend() == DECREASING;
+ bool IsIncreasingSurvivalTrend() {
+ return survival_rate_trend() == INCREASING;
}
bool IsHighSurvivalRate() {
return high_survival_rate_period_length_ > 0;
}
+ bool IsLowSurvivalRate() {
+ return low_survival_rate_period_length_ > 0;
+ }
+
void SelectScavengingVisitorsTable();
void StartIdleRound() {
--
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