ParNew 4x slower under 1.7 vs 1.6?

[Andrew Mulholland]

Hi Jon


On 8/12/13 5:50 AM, "Jon Masamitsu" <jon.masamitsu at oracle.com> wrote:

>
>I saw your response to  Bernd where you verified
>the number of GC threads that you are using but the
>amount of parallelism your getting still doesn't seem to
>be right.  See below.


Thanks - data below as requested:

>
>, 0.0989930 secs] [Times: user=0.46 sys=0.02, real=0.10 secs]
>
>
>
>About a 4 times speed up here (user / real ~ 4.6)
>

For JVM 1.6.0_43:

90% of ParNew Gcs had parallelism of at least: 5.17
75% of ParNew Gcs had parallelism of at least: 5.83
50% of ParNew Gcs had parallelism of at least: 6.71
25% of ParNew Gcs had parallelism of at least 7.66
10% of ParNew Gcs had parallelism of at least 8.5

Average parallelism for ParNew Gs: 6.75 (stdev 1.21)
Max Parallelism for ParNew GCs: 9


>
>, 0.4156130 secs] [Times: user=0.65 sys=0.02, real=0.42 secs]
>
>
>Only about a 1.5 times speed up here (user / real ~1.5).

For JVM 1.7.0_25:

90% of ParNew Gcs had parallelism of at least 1.53

75% of ParNew Gcs had parallelism of at least 1.63
50% of ParNew Gcs had parallelism of at least 2
25% of ParNew Gcs had parallelism of at least: 2.72
10% of ParNew Gcs had parallelism of at least: 5.32

Average parallelism for ParNew GCs: 2.58 (stdev 1.51)

Max Parallelism for ParNew GCs: 8.6





>
>Can you check some other entries and verify that the amount of
>parallelism your seeing on 1.7 is only 1.5.
>


>From the above it seems that we do get higher than 1.5.. With jvm 1.7 -
but it is consistently significantly lower than on jvm 1.6

Thanks


Andrew