Bug ID: JDK-6631166 CMS: better heuristics when combatting fragmentation

Type: Enhancement
Component: hotspot
Sub-Component: gc
Affected Version: hs10,hs14,6u14,6u16,6u17,7

Priority: P2
Status: Closed
Resolution: Fixed
OS:
generic,linux,linux_redhat_5.0,solaris_10 generic,linux,linux_redhat_5.0,solaris_10
CPU: generic,x86,sparc

Submitted: 2007-11-16
Updated: 2021-10-05
Resolved: 2010-07-02

Versions (Unresolved/Resolved/Fixed)

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Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

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JDK 6	JDK 7	Other
6u19-revFixed	7Fixed	hs16.2Fixed

See comments section for pointers to logs from customer and
an email that hints at (some of) the issues involved.

EVALUATION http://hg.openjdk.java.net/jdk7/hotspot/hotspot/rev/e018e6884bd8
09-01-2010
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/e018e6884bd8
24-12-2009
EVALUATION Under testing and review.
26-10-2009
EVALUATION In the case of this customer, one problem had been the extremely large size of OldPLABSize chosen. Reducing it improved fragmentation behaviour. However, their workloads are sufficiently high and sufficiently bursty that any dynamic scheme will be unable to work well at all times within a 32-bit heap. They have been advised to either move to 64-bit heaps and/or to run multiple 32-bit jvms to make full use of their multicore boxes. In the meantime, our investigations have identified a number of incremental improvements to reduce fragmentation and these are being tested. A list of improvements made as part of this CR will be listed in the suggested fix section when we are done.
23-10-2008
SUGGESTED FIX http://analemma.sfbay.sun.com/net/spot/workspaces/ysr/frag
23-10-2008
EVALUATION Some improvements have been made, and we are studying the effect of this on performance of some applications/benchmarks.
21-10-2008
EVALUATION We are investigating the defficiencies of the current scheme in order to improve the frgamentation-control heuristics.
20-11-2007

Duplicate :	JDK-6859722 - 6u14 Frequent ParNew promotion failure degrades performance
Duplicate :	JDK-2189686 - scavanging times increase after every Full GC
Duplicate :	JDK-6933076 - scavanging times increase after every Full GC
Duplicate :	JDK-6755514 - CMS: sharpen asserts related to free list consistency and locking
Duplicate :	JDK-6876575 - CMS: getChunkFromIndexedFreeListHelper() should allocate from larger indexed free list sizes
Relates :	JDK-6999988 - CMS: Increased fragmentation leading to promotion failure after CR#6631166 got implemented
Relates :	JDK-6916968 - CMS: freeList.cpp:304 assert(_allocation_stats.prevSweep() + ..., "Conservation Principle")
Relates :	JDK-6937526 - Support new VM argument type in sun.management.Flag
Relates :	JDK-6915365 - assert(false,"Unsupported VMGlobal Type") at management.cpp:1540
Relates :	JDK-6984429 - CMS: Crash due to a corrupted heap or frame, possibly because of a missing card-mark or other issue.
Relates :	JDK-2190628 - assert(false,"Unsupported VMGlobal Type") at management.cpp:1540
Relates :	JDK-6924497 - HotSpotDiagnosticsMXBean.getDiagnosticOptions throws NPE