G1 performance

Monica Beckwith monica.beckwith at oracle.com
Mon May 13 18:30:17 UTC 2013


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

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Monica Beckwith | Principal Member of Technical Staff
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Oracle Java Performance

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