JDK7u45 Young GC pause time increasing with increasing total heap, but it is not the case with JDK6

[nitin jalan]

Hi,

I was analyzing the impact of minor GC pause time on SUN JDK6 and JDK7 for
my low latency application.

I noticed that with ParallelGCThreads of 18, JDK7u45 is taking ~14-15 msec
on 30GB total heap with 5 GB Young generation size as compared to ~9-10
msec on 10GB total heap with 5 GB Young generation size.

Application host machine specification:
4 x 2.00GHz Hex-Core Intel(R) Xeon(R) CPU E7540 Linux RAM 62 GB

I am using CMS collector and my settings are:

-Xloggc:GC.log -server -XX:+PrintGCDetails -XX:+PrintGCDateStamps -Xms10g
-Xmx10g -XX:ReservedCodeCacheSize=512m -XX:CompileThreshold=50
-XX:MaxNewSize=5g -XX:NewSize=5g -XX:PermSize=128m -XX:MaxPermSize=128m
-Dcom.sun.management.jmxremote.port=9100
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=false -XX:+UseConcMarkSweepGC
-XX:-UseBiasedLocking -XX:-UseCounterDecay -XX:ParallelGCThreads=18
-XX:+UnlockDiagnosticVMOptions -XX:ParGCCardsPerStrideChunk=4096

i am attaching the log files with 10 GB and with 30 GB total heap.

Thanks and Regards
-Nitin
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