RFR: JDK-8086056: ParNew: auto-tune ParGCCardsPerStrideChunk

Jon Masamitsu jon.masamitsu at oracle.com
Thu Jun 18 01:44:49 UTC 2015


Tony,

I'm still studying the patch but would you consider a more explicit
flag to turn this on and off?  What you have is very reasonable but
if the performance team sees some regression, it would be easier
for them to turn the feature on or off rather than go look for the value
of ParGCCardsPerStrideChunk that is the default and then put that
on the command line.  Same would be true for a customer who has
an application operating in one of the corners where the performance
is worse.

Jon

On 6/17/2015 3:30 PM, Tony Printezis wrote:
> Hi all,
>
> A small patch for your consideration:
>
> http://cr.openjdk.java.net/~tonyp/8086056/webrev.0/ 
> <http://cr.openjdk.java.net/%7Etonyp/8086056/webrev.0/>
>
> (BTW, for some reason some of the webrev output is a bit messed up. 
> Not sure why, maybe some hg incompatibility I guess. The diffs look OK 
> though. I also attached the patch to this e-mail.)
>
> There’s a bit of info on the JIRA on the rationale for the patch:
>
> https://bugs.openjdk.java.net/browse/JDK-8086056
>
> The min / max values for the old gen capacity 
> and ParGCCardsPerStrideChunk were chosen empircally after running a 
> few (mostly synthetic tests) on Linux x64. If someone has the cycles 
> to do a more extensive performance study, I’d be happy to revise them 
> accordingly.
>
> Regards,
>
> Tony
>
> -----
>
> Tony Printezis | JVM/GC Engineer / VM Team | Twitter
>
> @TonyPrintezis
> tprintezis at twitter.com <mailto:tprintezis at twitter.com>
>

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