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8005452: NPG: Create new flags for Metaspace resizing policy

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Reviewed-by: johnc, jwilhelm, coleenp, stefank
This commit is contained in:
Jon Masamitsu 2013-01-23 19:08:04 -08:00
parent 251a9ff39c
commit c727c73cce
3 changed files with 31 additions and 7 deletions
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10
hotspot/src/share/vm/memory/metaspace.cpp
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@ -1064,11 +1064,11 @@ bool VirtualSpaceList::contains(const void *ptr) {
//
// After the GC the compute_new_size() for MetaspaceGC is called to
// resize the capacity of the metaspaces. The current implementation
// is based on the flags MinHeapFreeRatio and MaxHeapFreeRatio used
// is based on the flags MinMetaspaceFreeRatio and MaxHeapFreeRatio used
// to resize the Java heap by some GC's. New flags can be implemented
// if really needed. MinHeapFreeRatio is used to calculate how much
// free space is desirable in the metaspace capacity to decide how much
// to increase the HWM. MaxHeapFreeRatio is used to decide how much
// to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
// free space is desirable in the metaspace capacity before decreasing
// the HWM.
@ -1166,7 +1166,7 @@ void MetaspaceGC::compute_new_size() {
size_t capacity_until_GC = vsl->capacity_bytes_sum();
size_t free_after_gc = capacity_until_GC - used_after_gc;
const double minimum_free_percentage = MinHeapFreeRatio / 100.0;
const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
const double maximum_used_percentage = 1.0 - minimum_free_percentage;
const double min_tmp = used_after_gc / maximum_used_percentage;
@ -1232,8 +1232,8 @@ void MetaspaceGC::compute_new_size() {
max_shrink_words));
// Should shrinking be considered?
if (MaxHeapFreeRatio < 100) {
const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;
if (MaxMetaspaceFreeRatio < 100) {
const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
const double minimum_used_percentage = 1.0 - maximum_free_percentage;
const double max_tmp = used_after_gc / minimum_used_percentage;
size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));

18
hotspot/src/share/vm/runtime/arguments.cpp
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@ -1896,6 +1896,24 @@ bool Arguments::check_vm_args_consistency() {
// Keeping the heap 100% free is hard ;-) so limit it to 99%.
MinHeapFreeRatio = MIN2(MinHeapFreeRatio, (uintx) 99);
// Min/MaxMetaspaceFreeRatio
status = status && verify_percentage(MinMetaspaceFreeRatio, "MinMetaspaceFreeRatio");
status = status && verify_percentage(MaxMetaspaceFreeRatio, "MaxMetaspaceFreeRatio");
if (MinMetaspaceFreeRatio > MaxMetaspaceFreeRatio) {
jio_fprintf(defaultStream::error_stream(),
"MinMetaspaceFreeRatio (%s" UINTX_FORMAT ") must be less than or "
"equal to MaxMetaspaceFreeRatio (%s" UINTX_FORMAT ")\n",
FLAG_IS_DEFAULT(MinMetaspaceFreeRatio) ? "Default: " : "",
MinMetaspaceFreeRatio,
FLAG_IS_DEFAULT(MaxMetaspaceFreeRatio) ? "Default: " : "",
MaxMetaspaceFreeRatio);
status = false;
}
// Trying to keep 100% free is not practical
MinMetaspaceFreeRatio = MIN2(MinMetaspaceFreeRatio, (uintx) 99);
if (FullGCALot && FLAG_IS_DEFAULT(MarkSweepAlwaysCompactCount)) {
MarkSweepAlwaysCompactCount = 1; // Move objects every gc.
}

10
hotspot/src/share/vm/runtime/globals.hpp
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@ -3010,10 +3010,16 @@ class CommandLineFlags {
"Min change in heap space due to GC (in bytes)") \
\
product(uintx, MinMetaspaceExpansion, ScaleForWordSize(256*K), \
"Min expansion of permanent heap (in bytes)") \
"Min expansion of Metaspace (in bytes)") \
\
product(uintx, MinMetaspaceFreeRatio, 40, \
"Min percentage of Metaspace free after GC to avoid expansion") \
\
product(uintx, MaxMetaspaceFreeRatio, 70, \
"Max percentage of Metaspace free after GC to avoid shrinking") \
\
product(uintx, MaxMetaspaceExpansion, ScaleForWordSize(4*M), \
"Max expansion of permanent heap without full GC (in bytes)") \
"Max expansion of Metaspace without full GC (in bytes)") \
\
product(intx, QueuedAllocationWarningCount, 0, \
"Number of times an allocation that queues behind a GC " \