RFR (S): 8079208: gc/g1/TestLargePageUseForAuxMemory.java fails due to not considering page allocation granularity for setup

Eric Caspole eric.caspole at oracle.com
Wed May 13 18:15:45 UTC 2015

Hi Thomas,
Looks good,

On 05/13/2015 11:03 AM, Thomas Schatzl wrote:
> Hi all,
>    can I have reviews for the following test fix: the problem is that
> during test setup, when trying to find the heap size where large pages
> are just not used, the code subtracts a fixed value from the one known
> to use large pages for the card table.
> The problem is that this fixed value is too small to have an impact on
> the actual size of the card table, i.e. the code rounds up by the OS'es
> allocation granularity. That causes it to use the same size as before,
> where it will then use large pages anyway and fail the test.
> That fixed value has been just large enough to cover regular page size.
> Also, the only OS that has different allocation granularities and
> (small) page sizes is Windows. Further on Windows, large pages (and the
> test is only executed then) are only available when the user runs as
> Administrator (or has the corresponding capability to lock pages in
> memory).
> In this case the test fails.
> The change fixes this by making sure that this value to subtract from
> the original heap size is exactly the size that avoids this rounding.
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8079208
> Webrevs:
> http://cr.openjdk.java.net/~tschatzl/8079208/webrev/ (for hotspot
> changes)
> http://cr.openjdk.java.net/~tschatzl/8079208/webrev.hs-gc/ (for changes
> in the hs-gc directory, i.e. whitebox.java)
> Testing:
> Manual testing, jprt
> Thanks,
>    Thomas

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