RFR (XS): 8053998: Hot card cache flush chunk size too coarse grained

Marcus Larsson marcus.larsson at oracle.com
Wed Aug 20 13:42:27 UTC 2014


Hello,

On 08/18/2014 04:50 PM, Mikael Gerdin wrote:
> Hi Marcus,
>
> On 2014-08-18 09:27, Marcus Larsson wrote:
>> Hi,
>>
>> Can I have reviews for this small patch changing the hot card cache
>> flush chunks to a fixed size?
>>
>> CR:
>> http://cr.openjdk.java.net/~mgerdin/mlarsson/webrev-8053998/
>
> Can you move the value "32" to a constant? Both stringTable.cpp and 
> symbolTable.cpp define a
> const int ClaimChunkSize = 32;
> That seems like a reasonable pattern, but you should probably make it 
> a static global or scope it inside G1HotCardCache.

Made it a static constant in G1HotCardCache.

New webrev:
http://cr.openjdk.java.net/~mgerdin/mlarsson/webrev-8053998v2/

>
> Otherwise it looks good.
>
> For the record I asked Marcus about the value "32" and he had done 
> some experiments to come up with the number.

Yes, I should have mentioned this in my first email.
I measured with some different fixed sizes, and also by 
over-partitioning the cache to 10 chunks per active worker thread.
The smaller the chunk size the better results I got, so 32 seemed like a 
good number without making it too small.

>
> /Mikael
>
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8053998
>>
>> Testing:
>> jprt, SPECjbb2013
>>
>> Thanks,
>> Marcus

Thanks,
Marcus


More information about the hotspot-gc-dev mailing list