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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
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@ -81,20 +81,24 @@ void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) {
remove_expired_entries(end);
if (_no_entries == QueueLength) {
// OK, right now when we fill up we bomb out
// there are a few ways of dealing with this "gracefully"
// OK, we've filled up the queue. There are a few ways
// of dealing with this "gracefully"
// increase the array size (:-)
// 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
// (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
// uncommon; in such cases, we can, without much loss of precision
// or performance (we are GC'ing most of the time anyway!),
// simply overwrite the oldest entry in the tracker: this
// is also the behaviour when G1UseFixedWindowMMUTracker is enabled.
// simply overwrite the oldest entry in the tracker.
if (G1PolicyVerbose > 1) {
warning("MMU Tracker Queue overflow. Replacing earliest entry.");
}
_head_index = trim_index(_head_index + 1);
assert(_head_index == _tail_index, "Because we have a full circular buffer");
_tail_index = trim_index(_tail_index + 1);