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Bug ID: JDK-6984368 Large default heap size does not allow to use zero based compressed oops.
JDK-6984368 : Large default heap size does not allow to use zero based compressed oops.

Details
Type:
Bug
Submit Date:
2010-09-13
Status:
Closed
Updated Date:
2011-03-08
Project Name:
JDK
Resolved Date:
2011-03-08
Component:
hotspot
OS:
solaris_10
Sub-Component:
compiler
CPU:
sparc
Priority:
P4
Resolution:
Fixed
Affected Versions:
hs19
Fixed Versions:
hs19 (b07)

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Sub Tasks

Description
For 64 bit VM the default heap size is set to 1/4 of available physical memory. With memory > 120Gb the default heap size would be set to about 30Gb when compressed oops are used. It is fine for regular compressed oops but a little big for zero based compressed oops since lower part of virtual memory is used by os.

                                    

Comments
EVALUATION

The heap size expression in max_heap_for_compressed_oops() does not take into account HeapBaseMinAddress value used for zero based compressed oops.
                                     
2010-09-13
EVALUATION

http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/a8b66e00933b
                                     
2010-09-15
PUBLIC COMMENTS

The heap size expression in max_heap_for_compressed_oops()
does not take into account HeapBaseMinAddress value which
is used to get zero based compressed oops.

Also MaxPermSize is rounded up in CollectorPolicy::initialize_flags()
which makes invalid all expressions which use it before rounding.
                                     
2010-09-15
EVALUATION

http://hg.openjdk.java.net/jdk7/hotspot-rt/hotspot/rev/a8b66e00933b
                                     
2010-09-28
EVALUATION

http://hg.openjdk.java.net/hsx/hsx19/baseline/rev/4cf84525dc4d
                                     
2010-10-08
EVALUATION

http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/a8b66e00933b
                                     
2010-10-09



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