RFR: 10: 8160638: solaris JVM unable to allocate more than 2GB of direct byte buffers when max heap is <= 2GB

[Vladimir Kozlov]

Looks good to me. Someone from Runtime have to review this too.

Thanks,
Vladimir

On 4/10/17 6:30 AM, Vladimir Kempik wrote:
> Hello
>
> Please review this fix for bug JDK-8160638
> <https://bugs.openjdk.java.net/browse/JDK-8160638>
>
> The issue is with solaris only.
>
> When java mmaps heap (with compressed Oops enabled), mmaped heap become
> upper limit for any native mallocs.
>
> So when heap is starting at 2 gb, the maximum we can malloc is 2gb.
>
> Native malloc is used by Direct Memory Buffers, so even with
> -XX:MaxDirectMemorySize=100g we are still limited with less than 2 gb of
> memory for Direct Memory Buffers.
>
> The fix moves HeapBaseMinAddress to upper space when it's needed for
> MaxDirectMemorySize to operate properly, leaving about 1 gb of native
> memory for java's needs.
>
> Testing: jprt, included testcase.
>
> Webrev - http://cr.openjdk.java.net/~vkempik/8160638/webrev.00/
>
> Bug - https://bugs.openjdk.java.net/browse/JDK-8160638
>
> Thanks, Vladimir
>