ParNew pauses longer in JDK7

[Shane Cox]

While benchmarking my application on JDK7, I noticed that minor GC pauses are longer compared to JDK6.  One clue may relate to heap size.  I noticed that heap size (Xmx) has much more impact on minor GC in JDK7.  This is what I have observed:

JDK6 w/ 1GB heap:  avg minor GC pause = 3.9ms
JDK6 w/ 10GB heap:  avg minor GC pause = 3.9ms
JDK7 w/ 1GB heap:  avg minor GC pause = 5ms
JDK7 w/ 10GB heap: avg minor GC pause = 13.3ms

GC logs attached.  Platform info below.

Any help understanding this behavior would be appreciated.

java version "1.6.0_27"
Java(TM) SE Runtime Environment (build 1.6.0_27-b07)
Java HotSpot(TM) 64-Bit Server VM (build 20.2-b06, mixed mode)

java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)

-d64 -Xms1000m -Xmx1000m -XX:MaxNewSize=168M -XX:PermSize=48m -XX:MaxPermSize=96m -Xnoclassgc -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=80 -XX:+PrintGCDateStamps -XX:+PrintGCDetails -verbose:gc -Xloggc:./logs/gc-output.log

HP ProLiant DL360 G7
Intel(R) Xeon(R) CPU           X5670  @ 2.93GHz
Red Hat Enterprise Linux Server release 6.4 (Santiago)
Linux ll-lt-fxmr-03 2.6.32-358.2.1.el6.x86_64 #1 SMP Wed Feb 20 12:17:37 EST 2013 x86_64 x86_64 x86_64 GNU/Linux

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