review(XS) 7040485: Use transparent huge page on linux by default

[Igor Veresov]

Ramki,

Sure!

Webrev: http://cr.openjdk.java.net/~iveresov/7040485/webrev.01/

igor

On 4/28/11 3:28 PM, Y. S. Ramakrishna wrote:
> Looks good to me. I guess I missed this nuance in my
> previour review. Thanks also for fixing the return value.
>
> I had one comment about large_page_init(): it returns a
> boolean value and sets the value of UseLargePages (on
> Solaris and Linux). The caller then uses the return
> value to set the value of UseLargePages again. Seems
> a bit unpleasant. [Windows doesn't set the value
> in large_page_init(); the caller uses the return
> value to set UseLargePages.]
>
> What if the return value was just discarded and the
> value of the flag always set in the method itself
> prior to return? (You would then change the method
> in the windows implementation, and change the callers
> in the solaris and linux versions.]
>
> But of course all of that predates your current changes,
> and is not directly related to the synopsis, so would
> just be a small related clean-up you might want to roll into
> your changset. Your choice.
>
> -- ramki
>
> On 04/28/11 15:06, Igor Veresov wrote:
>> We should enable the use of transparent huge pages on Linux by
>> default. The solution is to set the UseLargePages flag to true by
>> default, but try only using UseHugeTLBFS by default if UseLargePages
>> is not specified on the command line. We would try both UseSHM and
>> UseHugeTLBFS methods if UseLargePages is explicitly set.
>> This way we maintain compatibility and do not start eating into shared
>> memory by default.
>>
>> Webrev: http://cr.openjdk.java.net/~iveresov/7040485/webrev.00/
>>
>>
>> Thanks,
>> igor