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6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads

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Select number of GC threads dynamically based on heap usage and number of Java threads

Reviewed-by: johnc, ysr, jcoomes
This commit is contained in:
Jon Masamitsu 2011-08-09 10:16:01 -07:00
parent 098ed89645
commit 15070123fa
39 changed files with 1523 additions and 231 deletions
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33
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
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@ -4244,9 +4244,11 @@ void CMSConcMarkingTask::coordinator_yield() {
bool CMSCollector::do_marking_mt(bool asynch) {
assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition");
// In the future this would be determined ergonomically, based
// on #cpu's, # active mutator threads (and load), and mutation rate.
int num_workers = ConcGCThreads;
int num_workers = AdaptiveSizePolicy::calc_active_conc_workers(
conc_workers()->total_workers(),
conc_workers()->active_workers(),
Threads::number_of_non_daemon_threads());
conc_workers()->set_active_workers(num_workers);
CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace();
CompactibleFreeListSpace* perm_space = _permGen->cmsSpace();
@ -5062,6 +5064,8 @@ class CMSParRemarkTask: public AbstractGangTask {
ParallelTaskTerminator _term;
public:
// A value of 0 passed to n_workers will cause the number of
// workers to be taken from the active workers in the work gang.
CMSParRemarkTask(CMSCollector* collector,
CompactibleFreeListSpace* cms_space,
CompactibleFreeListSpace* perm_space,
@ -5544,7 +5548,15 @@ void CMSCollector::do_remark_parallel() {
GenCollectedHeap* gch = GenCollectedHeap::heap();
FlexibleWorkGang* workers = gch->workers();
assert(workers != NULL, "Need parallel worker threads.");
int n_workers = workers->total_workers();
// Choose to use the number of GC workers most recently set
// into "active_workers". If active_workers is not set, set it
// to ParallelGCThreads.
int n_workers = workers->active_workers();
if (n_workers == 0) {
assert(n_workers > 0, "Should have been set during scavenge");
n_workers = ParallelGCThreads;
workers->set_active_workers(n_workers);
}
CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace();
CompactibleFreeListSpace* perm_space = _permGen->cmsSpace();
@ -5884,8 +5896,17 @@ void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) {
// and a different number of discovered lists may have Ref objects.
// That is OK as long as the Reference lists are balanced (see
// balance_all_queues() and balance_queues()).
rp->set_active_mt_degree(ParallelGCThreads);
GenCollectedHeap* gch = GenCollectedHeap::heap();
int active_workers = ParallelGCThreads;
FlexibleWorkGang* workers = gch->workers();
if (workers != NULL) {
active_workers = workers->active_workers();
// The expectation is that active_workers will have already
// been set to a reasonable value. If it has not been set,
// investigate.
assert(active_workers > 0, "Should have been set during scavenge");
}
rp->set_active_mt_degree(active_workers);
CMSRefProcTaskExecutor task_executor(*this);
rp->process_discovered_references(&_is_alive_closure,
&cmsKeepAliveClosure,