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6937160: G1: should observe GCTimeRatio

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Remove the G1GCPercent parameter, that specifies the desired GC overhead percentage in G1, and observe the GCTimeRatio parameter instead.

Reviewed-by: jmasa, johnc
This commit is contained in:
Antonios Printezis 2010-03-30 15:36:55 -04:00
parent 3eab898282
commit 972acdab81
4 changed files with 21 additions and 5 deletions
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11
hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp
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@ -198,7 +198,9 @@ G1CollectorPolicy::G1CollectorPolicy() :
_recorded_survivor_regions(0),
_recorded_survivor_head(NULL),
_recorded_survivor_tail(NULL),
_survivors_age_table(true)
_survivors_age_table(true),
_gc_overhead_perc(0.0)
{
// Set up the region size and associated fields. Given that the
@ -275,6 +277,11 @@ G1CollectorPolicy::G1CollectorPolicy() :
// calculate_young_list_target_config during initialization
_max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
assert(GCTimeRatio > 0,
"we should have set it to a default value set_g1_gc_flags() "
"if a user set it to 0");
_gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
initialize_all();
}
@ -2288,7 +2295,7 @@ G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
}
size_t G1CollectorPolicy::expansion_amount() {
if ((int)(recent_avg_pause_time_ratio() * 100.0) > G1GCPercent) {
if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
// We will double the existing space, or take
// G1ExpandByPercentOfAvailable % of the available expansion
// space, whichever is smaller, bounded below by a minimum

2
hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp
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@ -215,6 +215,8 @@ protected:
SurvRateGroup* _survivor_surv_rate_group;
// add here any more surv rate groups
double _gc_overhead_perc;
bool during_marking() {
return _during_marking;
}

3
hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp
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@ -40,9 +40,6 @@
develop(bool, G1Gen, true, \
"If true, it will enable the generational G1") \
\
develop(intx, G1GCPercent, 10, \
"The desired percent time spent on GC") \
\
develop(intx, G1PolicyVerbose, 0, \
"The verbosity level on G1 policy decisions") \
\

10
hotspot/src/share/vm/runtime/arguments.cpp
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@ -1353,6 +1353,16 @@ void Arguments::set_g1_gc_flags() {
MarkStackSize / K, MarkStackSizeMax / K);
tty->print_cr("ConcGCThreads: %u", ConcGCThreads);
}
if (FLAG_IS_DEFAULT(GCTimeRatio) || GCTimeRatio == 0) {
// In G1, we want the default GC overhead goal to be higher than
// say in PS. So we set it here to 10%. Otherwise the heap might
// be expanded more aggressively than we would like it to. In
// fact, even 10% seems to not be high enough in some cases
// (especially small GC stress tests that the main thing they do
// is allocation). We might consider increase it further.
FLAG_SET_DEFAULT(GCTimeRatio, 9);
}
}
void Arguments::set_heap_size() {