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

[Ashish Saxena]

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,

Ashish
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