RFR: 8252221: Use multiple workers for Parallel GC pre-touching

[Thomas Schatzl]

Hi,

On 13.10.20 15:53, Amit Pawar wrote:
> On Fri, 9 Oct 2020 17:05:51 GMT, Amit Pawar <github.com+71302734+amitdpawar at openjdk.org> wrote:
> 
>>> Hi Thomas,
>>>
>>> PR is updated with suggested changes. Please review.
>>>
>>> Thanks,
>>> Amit
>>
>> Hi Thomas,
>>
>> I have fixed the build issue and also updated the PR with suggested changes. Thanks for testing and please check now.
>>
>> Thanks,
>> Amit
> 
> Hi Thomas,
> 
> Thanks for the your feedback and testing and good to hear that it passed 70%.
> 
> PR is updated as per your suggestions and please check.
> 
> I have another suggestion regarding "PreTouchParallelChunkSize" flag.
> The default value looks huge and reducing this value to 128MB improved startup time for both G1GC and ParallelGC.
> The following test are done with 1TB memory. Please see below.
> 
> ParallelGC = 0.5-1 sec.
> G1GC = 2-3 sec

   I filed https://bugs.openjdk.java.net/browse/JDK-8254699, although 
I'm not sure what this means since the comparison is lacking.

> 
> Also, the minimum value allowed is '1' and it should be similar to page size right ?

It should be at least a page size. We can change the CR as required.

> 
> Please check.
>
Thanks,
   Thomas