G1 performance

Srinivas Ramakrishna ysr1729 at gmail.com
Tue May 14 00:42:13 UTC 2013


Thanks a lot for those very useful pointers, Monica! I'll send you the logs
offline.

thanks!
-- ramki


On Mon, May 13, 2013 at 11:30 AM, Monica Beckwith <
monica.beckwith at oracle.com> wrote:

>  Ramki -
>
> Quick comments inlined -
> On 5/8/2013 3:31 PM, Srinivas Ramakrishna wrote:
>
> I have been playing with G1 a bit, and have noticed a nearly 10%
> overhead with G1, which is independent of the measured GC overheads.
> It's possible that this is because of the G1 write barriers inhibiting
> certain JIT optimizations.
>
>  I think Jon already mentioned one of our findings on this. Here's the
> related CR: http://bugs.sun.com/view_bug.do?bug_id=7183509
>
>  I have also seen, although this needs to be
> established more thoroughly, that G1's performance degrades the longer
> it runs, in the sense that minor GC pause times become progressively
> worse.
>
>  I would like to look at the logs, there could be issues like the
> following:
> http://bugs.sun.com/view_bug.do?bug_id=8004888
>
> Thanks for starting this thread.
>
> -Monica
>
>
> Has this kind of performance behaviour been observed by others on this
> list? Or internally at Oracle in performance testing of G1? Or by
> other power users of G1 out there?
>
> Basically, all of the experiments I have done seem to indicate that
> CMS performs better than G1, but unfortunately the potential
> fragmentation problem with CMS (followed by the promotion failure
> handling and the single-threaded compaction to follow) make it
> unsuitable in certain situations.
>
>
> thanks!
> -- ramki
>
>
> --
> [image: Oracle] <http://www.oracle.com>
> Monica Beckwith | Principal Member of Technical Staff
> VOIP: +15124011274
> Oracle Java Performance
>
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> committed to developing practices and products that help protect the
> environment
>
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