RFR (XS): JDK-8047976: Ergonomics for GC thread counts should update the flags

[Jesper Wilhelmsson]

Thomas Schatzl skrev 26/9/14 10:40:
> Hi Sangheon,
>
> On Fri, 2014-09-26 at 10:04 +0200, Bengt Rutisson wrote:
>> Hi all,
>>
>> Here's an updated webrev from Sangheon:
>>
>> http://cr.openjdk.java.net/~brutisso/8047976/webrev.02/
>>
>>   From Sangheon:
>>
>> "This includes Thomas's comments about:
>> 1) Moving value set to Arguments::set_g1_gc_flags()
>> 2) Adding jtreg test for G1ConcRefinementThreads variable"
>
> The changes in the Hotspot code look okay to me. Thanks!
>
> Some comments about the test case code:
>
> - There is a typo in AUTO_SELCT_THREADS_COUNT, should be
> AUTO_SELECT_THREADS_COUNT I think.
> - There is no need to have @build and @run lines if you do not use
> special options to invoke the test afaik.

Once this is fixed I'm fine with this change.
If you send an "hg export" of the change I'll push it.
/Jesper

>
> Otherwise looks okay.
>
> Thanks,
>    Thomas
>
>
>>
>> Thanks,
>> Bengt
>>
>>
>> On 2014-09-25 11:01, Thomas Schatzl wrote:
>>> Hi,
>>>
>>> On Thu, 2014-09-25 at 09:32 +0200, Thomas Schatzl wrote:
>>>> Hi,
>>>>
>>>> On Wed, 2014-09-24 at 08:51 -0700, Sangheon Kim wrote:
>>>>> Hi all,
>>>>>
>>>>> can I have reviews for the following small change to update
>>>>> G1ConcRefinementThreads variable?
>>>>> And also I need a sponsor for this.
>>>>>
>>>>> CR:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8047976
>>>>>
>>>>> Webrev:
>>>>> http://cr.openjdk.java.net/~brutisso/8047976/webrev.00/
>>>>> <http://cr.openjdk.java.net/%7Ebrutisso/8047976/webrev.00/>
>>>> Please update the flag during argument processing, not every time the
>>>> method is called.
>>>>
>>>> Somewhere in Arguments::set_g1_gc_flags() would be appropriate I think.
>>>>
>>> Please also add a jtreg test case. At least one test case that verifies
>>> that with G1 the G1ConcRefinementThreads is not zero if nothing or zero
>>> is passed, and another one that checks that the value passed is taken
>>> over.
>>>
>>> The test could parse the output of -XX:+PrintFlagsFinal. The test
>>> gc/arguments/TestObjectTenuringFlags.java shows how this is done.
>>>
>>> There is also some behavior that seems to be wrong: if you manually set
>>> the number of G1ConcRefinementThreads to zero (which means
>>> "automatically select"), -XX:+PrintFlagsFinal still prints
>>> "G1ConcRefinementThreads := 0". Imo even in this case the output should
>>> contain the actual number of threads used.
>>>
>>> At least if you set ConcGCThreads manually to 0, the flag is set to the
>>> actual value after argument processing.
>>>
>>> ParallelGCThreads also shows 0 here, but I think this part of bug
>>> JDK-6979279 and should be fixed there.
>>>
>>> Thanks,
>>>     Thomas
>>>
>>>
>>
>
>