FRF: 8216975 Using ForceNUMA does not disable adaptive sizing with parallel gc

[Ivan Walulya]

Thanks Leo!

> On 21 Feb 2020, at 10:45, Leo Korinth <leo.korinth at oracle.com> wrote:
> 
> Looks good, I will push for you.
> 
> Thanks,
> Leo
> 
> On 20/02/2020 09:04, Ivan Walulya wrote:
>> Hi all,
>> Here is the revised webrev: http://cr.openjdk.java.net/~iwalulya/8216975/01/ <http://cr.openjdk.java.net/~iwalulya/8216975/01/>
>> //Ivan
>>> On 19 Feb 2020, at 16:30, Kim Barrett <kim.barrett at oracle.com> wrote:
>>> 
>>>> On Feb 19, 2020, at 10:23 AM, Kim Barrett <kim.barrett at oracle.com> wrote:
>>>> 
>>>>> On Feb 19, 2020, at 3:35 AM, Ivan Walulya <ivan.walulya at oracle.com> wrote:
>>>>> 
>>>>> Hi all,
>>>>> 
>>>>> Please review a minor modification to disable adaptive sizing when ForceNuma is used with ParallelGC and UseLargePages on Linux OS.
>>>>> 
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8216975
>>>>> <https://bugs.openjdk.java.net/browse/JDK-8216975>Webrev: http://cr.openjdk.java.net/~iwalulya/8216975/00/ <http://cr.openjdk.java.net/~iwalulya/8216975/00/>
>>>>> Testing: Tier 1 - 3
>>>>> 
>>>>> 
>>>>> //Ivan
>>>> 
>>>> Setting UseNUMA true when Linux::libnuma_init returns false seems
>>>> unlikely to work.  The description of ForceNUMA is
>>>> 
>>>>   Force NUMA optimizations on single-node/UMA systems
>>>> 
>>>> which suggests how it's presently being used in numa_init is wrong.  I
>>>> think the current use should be removed and this conditional clause
>>>> 
>>>> 5129       // If there's only one node (they start from 0) or if the process
>>>> 5130       // is bound explicitly to a single node using membind, disable NUMA.
>>>> 5131       UseNUMA = false;
>>>> 
>>>> should instead use
>>>> 
>>>> UseNUMA = ForceNUMA
>>> 
>>> The Solaris use of ForceNUMA looks like it has a similar problem.
>>> 
>>> On Windows, UseNUMA seems to get forced off unless ForceNUMA, because
>>> NUMA support isn’t complete there.  Which is an entirely different meaning for
>>> ForceNUMA from its description.
>>> 
>>> That covers all the uses of ForceNUMA.
>>>