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7192128: G1: Extend fix for 6948537 to G1's BOT

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G1 does not appear to be immune to the issue described in CR 6948537 and increasing the size of old-generation PLABs appears to increase the liklihood of seeing the issue. Extend the fix for 6948537 to G1's BlockOffsetTable.

Reviewed-by: brutisso, jmasa
This commit is contained in:
John Cuthbertson 2012-08-21 10:05:57 -07:00
parent b11a680280
commit 384650cb3e
3 changed files with 32 additions and 8 deletions
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8
hotspot/src/cpu/sparc/vm/vm_version_sparc.cpp
View file

@ -106,10 +106,10 @@ void VM_Version::initialize() {
if (FLAG_IS_DEFAULT(OptoLoopAlignment)) { if (FLAG_IS_DEFAULT(OptoLoopAlignment)) {
FLAG_SET_DEFAULT(OptoLoopAlignment, 4); FLAG_SET_DEFAULT(OptoLoopAlignment, 4);
} }
// When using CMS, we cannot use memset() in BOT updates because // When using CMS or G1, we cannot use memset() in BOT updates
// the sun4v/CMT version in libc_psr uses BIS which exposes // because the sun4v/CMT version in libc_psr uses BIS which
// "phantom zeros" to concurrent readers. See 6948537. // exposes "phantom zeros" to concurrent readers. See 6948537.
if (FLAG_IS_DEFAULT(UseMemSetInBOT) && UseConcMarkSweepGC) { if (FLAG_IS_DEFAULT(UseMemSetInBOT) && (UseConcMarkSweepGC || UseG1GC)) {
FLAG_SET_DEFAULT(UseMemSetInBOT, false); FLAG_SET_DEFAULT(UseMemSetInBOT, false);
} }
#ifdef _LP64 #ifdef _LP64

18
hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp
View file

@ -1,5 +1,5 @@
/* /*
* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
* *
* This code is free software; you can redistribute it and/or modify it * This code is free software; you can redistribute it and/or modify it
@ -159,14 +159,30 @@ private:
"right address out of range"); "right address out of range");
assert(left < right, "Heap addresses out of order"); assert(left < right, "Heap addresses out of order");
size_t num_cards = pointer_delta(right, left) >> LogN_words; size_t num_cards = pointer_delta(right, left) >> LogN_words;
if (UseMemSetInBOT) {
memset(&_offset_array[index_for(left)], offset, num_cards); memset(&_offset_array[index_for(left)], offset, num_cards);
} else {
size_t i = index_for(left);
const size_t end = i + num_cards;
for (; i < end; i++) {
_offset_array[i] = offset;
}
}
} }
void set_offset_array(size_t left, size_t right, u_char offset) { void set_offset_array(size_t left, size_t right, u_char offset) {
assert(right < _vs.committed_size(), "right address out of range"); assert(right < _vs.committed_size(), "right address out of range");
assert(left <= right, "indexes out of order"); assert(left <= right, "indexes out of order");
size_t num_cards = right - left + 1; size_t num_cards = right - left + 1;
if (UseMemSetInBOT) {
memset(&_offset_array[left], offset, num_cards); memset(&_offset_array[left], offset, num_cards);
} else {
size_t i = left;
const size_t end = i + num_cards;
for (; i < end; i++) {
_offset_array[i] = offset;
}
}
} }
void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const { void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const {

8
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
View file

@ -1934,6 +1934,14 @@ G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
clear_cset_start_regions(); clear_cset_start_regions();
guarantee(_task_queues != NULL, "task_queues allocation failure."); guarantee(_task_queues != NULL, "task_queues allocation failure.");
#ifdef SPARC
// Issue a stern warning, but allow use for experimentation and debugging.
if (VM_Version::is_sun4v() && UseMemSetInBOT) {
assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error");
warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability"
" on sun4v; please understand that you are using at your own risk!");
}
#endif
} }
jint G1CollectedHeap::initialize() { jint G1CollectedHeap::initialize() {