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6941378: G1: change default value of G1UseFixedWindowMMUTracker to true

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Rather than changing the default value of the G1UseFixedWindowMMUTracker, the flag and associated guarantee have been removed.

Reviewed-by: jcoomes, tonyp, ysr
This commit is contained in:
John Cuthbertson 2010-05-24 17:11:22 -07:00
parent 8a34049f04
commit 9936975b96
2 changed files with 11 additions and 10 deletions
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18
hotspot/src/share/vm/gc_implementation/g1/g1MMUTracker.cpp
View file

@ -81,20 +81,24 @@ void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) {
remove_expired_entries(end); remove_expired_entries(end);
if (_no_entries == QueueLength) { if (_no_entries == QueueLength) {
// OK, right now when we fill up we bomb out // OK, we've filled up the queue. There are a few ways
// there are a few ways of dealing with this "gracefully" // of dealing with this "gracefully"
// increase the array size (:-) // increase the array size (:-)
// remove the oldest entry (this might allow more GC time for // remove the oldest entry (this might allow more GC time for
// the time slice than what's allowed) // the time slice than what's allowed) - this is what we
// currently do
// consolidate the two entries with the minimum gap between them // consolidate the two entries with the minimum gap between them
// (this might allow less GC time than what's allowed) // (this might allow less GC time than what's allowed)
guarantee(NOT_PRODUCT(ScavengeALot ||) G1UseFixedWindowMMUTracker,
"array full, currently we can't recover unless +G1UseFixedWindowMMUTracker");
// In the case where ScavengeALot is true, such overflow is not // In the case where ScavengeALot is true, such overflow is not
// uncommon; in such cases, we can, without much loss of precision // uncommon; in such cases, we can, without much loss of precision
// or performance (we are GC'ing most of the time anyway!), // or performance (we are GC'ing most of the time anyway!),
// simply overwrite the oldest entry in the tracker: this // simply overwrite the oldest entry in the tracker.
// is also the behaviour when G1UseFixedWindowMMUTracker is enabled.
if (G1PolicyVerbose > 1) {
warning("MMU Tracker Queue overflow. Replacing earliest entry.");
}
_head_index = trim_index(_head_index + 1); _head_index = trim_index(_head_index + 1);
assert(_head_index == _tail_index, "Because we have a full circular buffer"); assert(_head_index == _tail_index, "Because we have a full circular buffer");
_tail_index = trim_index(_tail_index + 1); _tail_index = trim_index(_tail_index + 1);

3
hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp
View file

@ -254,9 +254,6 @@
"If non-0 is the size of the G1 survivor space, " \ "If non-0 is the size of the G1 survivor space, " \
"otherwise SurvivorRatio is used to determine the size") \ "otherwise SurvivorRatio is used to determine the size") \
\ \
product(bool, G1UseFixedWindowMMUTracker, false, \
"If the MMU tracker's memory is full, forget the oldest entry") \
\
product(uintx, G1HeapRegionSize, 0, \ product(uintx, G1HeapRegionSize, 0, \
"Size of the G1 regions.") \ "Size of the G1 regions.") \
\ \