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8059758: Footprint regressions with JDK-8038423

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Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.

Reviewed-by: jwilhelm, brutisso
This commit is contained in:
Thomas Schatzl 2014-10-09 11:40:11 +02:00
parent 6d1c35615a
commit 60f3ade82b
11 changed files with 28 additions and 15 deletions
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5
hotspot/src/share/vm/gc_implementation/g1/g1CardCounts.cpp
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@ -33,7 +33,10 @@
PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
if (zero_filled) {
return;
}
MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
_counts->clear_range(mr);
}