Pls review 6887571

[Paul Hohensee]

Thanks for the review (and the previous one too).

Yes, I feel queasy about changing CMS ergo.  Using the code in
set_heap_size() with cms produced some pretty weird results, such
as initial gen1 sizes of 64kb.  I investigated a bit and decided to leave
well enough alone.  I'll be happy to file an rfe to integrate cms and
common heap ergo.  Would that be acceptable?

Paul

Y.S.Ramakrishna at Sun.COM wrote:
> On 10/27/09 15:12, Paul Hohensee wrote:
>> Yes, I forgot to uncomment line 1383.  Fixed.
>>
>> Fixed line 1612.
>
> Thanks.
>
>>
>> It's a good thing you asked me to get cms dumps.  Turned out I'd 
>> typo'ed and
>> had an earlier version of arguments.cpp.  The earlier version didn't 
>> separate
>> cms ergo from everything-else ergo.  New webrev here
>>
>> http://cr.openjdk.java.net/~phh/6887571/webrev.02/
>
> I think I will need to discuss this further with you. I actually prefer
> the older version you had where the heap size is set ergonomically unless
> explicitly specified in the case of CMS as well. The CMS ergo will take
> that as a given and _shape_ the generations within those constraints. 
> That would be
> my preferred model of CMS ergo -- basically, what you had in your
> earlier webrev. However, I understand if you and others feel leery about
> touching CMS ergo for other reasons and would prefer any such changes 
> to be
> affected in a subsequent CR which does due diligence in
> measuring the performance delta of that change for CMS specifically.
>
> -- ramki
>
>>
>> With the new version, running
>>
>> java -client -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -XX:+Verbose 
>> -version
>>
>> I get
>>
>> VM option '+UseConcMarkSweepGC'
>> VM option '+PrintGCDetails'
>> VM option '+Verbose'
>> Turning off use of shared archive because of choice of garbage 
>> collector or large pages
>> Ergo set MaxNewSize: 134217728
>> CMS set min_heap_size: 0 initial_heap_size:  0 max_heap: 100663296
>> Ergo set NewSize: 16777216
>> Ergo set OldSize: 50331648
>> Minimum heap 67108864  Initial heap 67108864  Maximum heap 100663296
>> Minimum gen0 16777216  Initial gen0 16777216  Maximum gen0 16777216
>> Minimum gen1 50331648  Initial gen1 50331648  Maximum gen1 83886080
>>
>> java version "1.7.0-ea"
>> Java(TM) SE Runtime Environment (build 1.7.0-ea-b39)
>> OpenJDK Client VM (build 17.0-b03-internal-jvmg, mixed mode)
>> Heap
>> par new generation   total 14784K, used 527K [0xf1800000, 0xf2800000, 
>> 0xf2800000)
>>  eden space 13184K,   4% used [0xf1800000, 0xf1883de8, 0xf24e0000)
>>  from space 1600K,   0% used [0xf24e0000, 0xf24e0000, 0xf2670000)
>>  to   space 1600K,   0% used [0xf2670000, 0xf2670000, 0xf2800000)
>> concurrent mark-sweep generation total 49152K, used 0K [0xf2800000, 
>> 0xf5800000, 0xf7800000)
>> concurrent-mark-sweep perm gen total 12288K, used 1497K [0xf7800000, 
>> 0xf8400000, 0xfb800000)
>>
>> With the unmodified vm, I get
>>
>> VM option '+UseConcMarkSweepGC'
>> VM option '+PrintGCDetails'
>> VM option '+Verbose'
>> Turning off use of shared archive because of choice of garbage 
>> collector or large pages
>> Ergo set MaxNewSize: 134217728
>> CMS set min_heap_size: 0 initial_heap_size:  0 max_heap: 67108864
>> Ergo set NewSize: 16777216
>> Ergo set OldSize: 50331648
>> Minimum heap 67108864  Initial heap 67108864  Maximum heap 67108864
>> Minimum gen0 16777216  Initial gen0 16777216  Maximum gen0 16777216
>> Minimum gen1 50331648  Initial gen1 50331648  Maximum gen1 50331648
>>
>> java version "1.7.0-ea"
>> Java(TM) SE Runtime Environment (build 1.7.0-ea-b39)
>> OpenJDK Client VM (build 17.0-b03-internal-jvmg, mixed mode)
>> Heap
>> par new generation   total 14784K, used 527K [0xf3800000, 0xf4800000, 
>> 0xf4800000)
>>  eden space 13184K,   4% used [0xf3800000, 0xf3883de8, 0xf44e0000)
>>  from space 1600K,   0% used [0xf44e0000, 0xf44e0000, 0xf4670000)
>>  to   space 1600K,   0% used [0xf4670000, 0xf4670000, 0xf4800000)
>> concurrent mark-sweep generation total 49152K, used 0K [0xf4800000, 
>> 0xf7800000, 0xf7800000)
>> concurrent-mark-sweep perm gen total 12288K, used 1497K [0xf7800000, 
>> 0xf8400000, 0xfb800000)
>>
>> They're identical, except for the total heap size and ergo-computed 
>> old gen
>> size, which are 96m and 80m respectively.  That's because I increased 
>> the
>> value of MaxNewSize from 64m to 96m.
>>
>> -server instead of -client produces the same result.
>>
>> Paul
>>
>> Y.S.Ramakrishna at Sun.COM wrote:
>>> Hi Paul --
>>>
>>> Did you forget to remove the commenting out of the second conjunct in
>>> arguments.cpp:1383 below:-
>>>
>>>   1383     if (PrintGCDetails/* && Verbose*/) {
>> Yes, fixed.
>>>
>>> Could you do me a favour and change the following in 
>>> arguments.cpp:1612 from:-
>>>
>>>   1612       if (UseSharedSpaces) {
>>>
>>> to:-
>>>
>>>   1612       if (UseSharedSpaces && Verbose) {
>>>
>>> The verbosity of the message at 1613:1615 has been
>>> bothering some of us for a while (mea culpa for adding
>>> it recentkly), but i didn't get around to removing it, and this
>>> looks like an good opportunity to do so with no new overhead :-)
>> Done.
>>>
>>> On 10/27/09 09:26, Paul Hohensee wrote:
>>> ...
>>>> 6. In arguments.cpp, set_heap_size() replaces 
>>>> set_server_heap_size() and is used for everything
>>>> except CMS.  CMS has it's own, incompatible (I know: I tried it), 
>>>> heap sizing ergonomics.
>>>
>>> Could you provide the result of:-
>>>
>>> % java -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -version
>>>
>>> with the baseline VM and with the VM after yr changes?
>>>
>>>
>>> Rest looks good to me; thanks!
>>> -- ramki
>>>
>