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8005396: Use ParNew with only one thread instead of DefNew as default for CMS on single CPU machines

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Reviewed-by: jmasa, jcoomes
This commit is contained in:
Bengt Rutisson 2012-12-30 08:47:52 +01:00
parent 15bae865ac
commit 53cdde9124
6 changed files with 39 additions and 51 deletions
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69
hotspot/src/share/vm/runtime/arguments.cpp
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@ -1083,10 +1083,6 @@ static void disable_adaptive_size_policy(const char* collector_name) {
}
}
// If the user has chosen ParallelGCThreads > 0, we set UseParNewGC
// if it's not explictly set or unset. If the user has chosen
// UseParNewGC and not explicitly set ParallelGCThreads we
// set it, unless this is a single cpu machine.
void Arguments::set_parnew_gc_flags() {
assert(!UseSerialGC && !UseParallelOldGC && !UseParallelGC && !UseG1GC,
"control point invariant");
@ -1095,42 +1091,41 @@ void Arguments::set_parnew_gc_flags() {
// Turn off AdaptiveSizePolicy for parnew until it is complete.
disable_adaptive_size_policy("UseParNewGC");
if (ParallelGCThreads == 0) {
FLAG_SET_DEFAULT(ParallelGCThreads,
Abstract_VM_Version::parallel_worker_threads());
if (ParallelGCThreads == 1) {
FLAG_SET_DEFAULT(UseParNewGC, false);
FLAG_SET_DEFAULT(ParallelGCThreads, 0);
}
if (FLAG_IS_DEFAULT(ParallelGCThreads)) {
FLAG_SET_DEFAULT(ParallelGCThreads, Abstract_VM_Version::parallel_worker_threads());
assert(ParallelGCThreads > 0, "We should always have at least one thread by default");
} else if (ParallelGCThreads == 0) {
jio_fprintf(defaultStream::error_stream(),
"The ParNew GC can not be combined with -XX:ParallelGCThreads=0\n");
vm_exit(1);
}
if (UseParNewGC) {
// By default YoungPLABSize and OldPLABSize are set to 4096 and 1024 respectively,
// these settings are default for Parallel Scavenger. For ParNew+Tenured configuration
// we set them to 1024 and 1024.
// See CR 6362902.
if (FLAG_IS_DEFAULT(YoungPLABSize)) {
FLAG_SET_DEFAULT(YoungPLABSize, (intx)1024);
}
if (FLAG_IS_DEFAULT(OldPLABSize)) {
FLAG_SET_DEFAULT(OldPLABSize, (intx)1024);
}
// AlwaysTenure flag should make ParNew promote all at first collection.
// See CR 6362902.
if (AlwaysTenure) {
FLAG_SET_CMDLINE(uintx, MaxTenuringThreshold, 0);
}
// When using compressed oops, we use local overflow stacks,
// rather than using a global overflow list chained through
// the klass word of the object's pre-image.
if (UseCompressedOops && !ParGCUseLocalOverflow) {
if (!FLAG_IS_DEFAULT(ParGCUseLocalOverflow)) {
warning("Forcing +ParGCUseLocalOverflow: needed if using compressed references");
}
FLAG_SET_DEFAULT(ParGCUseLocalOverflow, true);
}
assert(ParGCUseLocalOverflow || !UseCompressedOops, "Error");
// By default YoungPLABSize and OldPLABSize are set to 4096 and 1024 respectively,
// these settings are default for Parallel Scavenger. For ParNew+Tenured configuration
// we set them to 1024 and 1024.
// See CR 6362902.
if (FLAG_IS_DEFAULT(YoungPLABSize)) {
FLAG_SET_DEFAULT(YoungPLABSize, (intx)1024);
}
if (FLAG_IS_DEFAULT(OldPLABSize)) {
FLAG_SET_DEFAULT(OldPLABSize, (intx)1024);
}
// AlwaysTenure flag should make ParNew promote all at first collection.
// See CR 6362902.
if (AlwaysTenure) {
FLAG_SET_CMDLINE(uintx, MaxTenuringThreshold, 0);
}
// When using compressed oops, we use local overflow stacks,
// rather than using a global overflow list chained through
// the klass word of the object's pre-image.
if (UseCompressedOops && !ParGCUseLocalOverflow) {
if (!FLAG_IS_DEFAULT(ParGCUseLocalOverflow)) {
warning("Forcing +ParGCUseLocalOverflow: needed if using compressed references");
}
FLAG_SET_DEFAULT(ParGCUseLocalOverflow, true);
}
assert(ParGCUseLocalOverflow || !UseCompressedOops, "Error");
}
// Adjust some sizes to suit CMS and/or ParNew needs; these work well on