RFR (S): 8077255: TracePageSizes output reports wrong page size on Windows with G1

[Jon Masamitsu]

On 4/8/2015 6:57 AM, Thomas Schatzl wrote:
> Hi all,
>
>    can I have reviews for the following change that fixes the output of
> -XX:+TracePageSizes to report the expected values for page size.
> Instead of returning the value of the page size to be used for
> allocations, this returned the OS'es allocation granularity which is the
> same on all but Windows, where this test subsequently fails.
>
> I am not completely sure why this did not fail with the corresponding
> push. The test most of the time still passes.
>
> The change simply calculates the preferred page size and passes it to
> the ReservedSpace constructor where it is used if set. Otherwise, the
> ReservedSpace constructor calculates that value by itself as before.

So the behavior of create_aux_memory_mapper() is unchanged with the fix
except that preferred_page_size is calculated before the call to 
create_aux_memory_mapper()
and passed in to create_aux_memory_mapper() and printed for TracePageSizes.

If I'm understanding that correctly, change looks good.

Reviewed.

Jon
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8077255
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8077255/webrev.0/
> Testing:
> JPRT (supposedly running that test), manual verification of the -XX:
> +TracePageSizes output before and after the change with and without -XX:
> +UseLargePages.
>
> Thanks,
>    Thomas
>
>