G1: "Other" time too long ?
Simone Bordet
simone.bordet at gmail.com
Thu Dec 11 15:38:46 UTC 2014
Hi,
G1 with a 32 GiB heap (16 MiB region size), I was seeing high "Update
RS" and "Scan RS" times during mixed GCs.
I am aware of -XX:G1RSetRegionEntries, but I wanted to try another
path: whether reducing manually the region size caused less inter
region references and therefore reduced the probable coarsening that
was the cause of the long RS times.
So I set the region size to 2 MiB and re-run.
Now I get very high "Other" times, for example:
[Other: 464.1 ms]
[Choose CSet: 0.1 ms]
[Ref Proc: 52.4 ms]
[Ref Enq: 1.8 ms]
[Redirty Cards: 19.4 ms]
[Free CSet: 22.7 ms]
The sum of the subtask times is not close to the "Other" time so I was
wondering what else it's done in the "Other" processing, or whether
perhaps it is not reporting what I think (e.g. a sequential time vs a
parallel time).
I'd probably revert to a 16 MiB region size and setting
G1RSetRegionEntries, but I was wondering if someone can shed some
light on this.
Logs are too big for this mailing list, but I can provide them to
interested people.
Thanks !
--
Simone Bordet
http://bordet.blogspot.com
---
Finally, no matter how good the architecture and design are,
to deliver bug-free software with optimal performance and reliability,
the implementation technique must be flawless. Victoria Livschitz
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