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

[Y. S. Ramakrishna]

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