Request for review (L) - 6593758

poonam.bajaj at oracle.com poonam.bajaj at oracle.com
Thu Oct 27 22:28:54 PDT 2011


Hi Jon,

On 10/28/2011 12:11 AM, Jon Masamitsu wrote:
>
>
> On 10/27/11 02:49, poonam.bajaj at oracle.com wrote:
>> Hi Jon,
>>
>> I looked at some of the files and here are few comments:
>>
>> - concurrentMarkSweepGeneration.cpp, line 5551
>>
>> Here, flag UseDynamicNumberOfGCThreads can be checked to make the 
>> decision if we need to use 'active_workers', the way you have done it 
>> in collectionSetChooser.cpp at line 258
>
> What I meant to say was that at 5551 I wanted to use whatever value of
> active_workers that was calculated when calc_active_workers() was last
> called.  That would likely be the value at the last young GC or at the
> initial-mark.  I had at one point thought there was a dependency between
> the number of GC threads used in a young collection and the number used
> in the remark.  I've been told that is not the case but have not proven
> that to myself and since lots of testing has already been done with this
> code, I left it unchanged with a note to myself to look at it again.
>
> Did I understand your comment?

Yes.

So, if the active_workers was not set then we will not calculate the
active_workers with calc_active_workers() again and instead
use ParallelGCThreads.

Where in the code are the active_workers set for initial-marking
phase?

>>
>> - concurrentMarkSweepGeneration.cpp at line 5899
>>
>> same as above comment
>
> My intent was to set a number of GC workers for a
> collection (minor or full or initial-mark or remark)
> so didn't want to change within the collection (Reference
> processing being done as part of the remark) so that's
> why I'm here just using what has previously been
> calculated.
>
Ok.

>
>>
>> - concurrentMarkSweepGeneration.cpp, line 5552
>>
>> Mis-spelled in comments, "active_works" should be "active_workers"
>
> Fixed.

Thanks,
Poonam


>
> Thanks.
>
> Jon
>>
>>
>> Thanks,
>> Poonam
>>
>>
>> On 10/27/2011 4:41 AM, Jon Masamitsu wrote:
>>> 6593758: RFE: Enhance GC ergonomics to dynamically choose 
>>> ParallelGCThreads
>>>
>>> http://cr.openjdk.java.net/~jmasa/6593758/webrev.00/
>>>
>>> Thanks.
>>>
>>>
>>
>> -- 
>> Best regards, Poonam
>>
>> Oracle <http://www.oracle.com>
>> Poonam Bajaj | Principal Member of Technical Staff
>> Phone: +91 80 66937451 <tel:+91%2080%2066937451> | Mobile: +91 
>> 9844511366 <tel:+91%209844511366>
>> Oracle JVM Sustaining Engineering
>>
>> ORACLE India Bangalore
>> Green Oracle <http://www.oracle.com/commitment> Oracle is committed 
>> to developing practices and products that help protect the environment
>>

-- 
Best regards, Poonam

Oracle <http://www.oracle.com>
Poonam Bajaj | Principal Member of Technical Staff
Phone: +91 80 66937451 <tel:+91%2080%2066937451> | Mobile: +91 
9844511366 <tel:+91%209844511366>
Oracle JVM Sustaining Engineering

ORACLE India Bangalore
Green Oracle <http://www.oracle.com/commitment> Oracle is committed to 
developing practices and products that help protect the environment

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