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

[Leo Korinth]

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.
>>
>