Request for review (S): 7005808 G1: re-enable ReduceInitialCardMarks for G1

Y. S. Ramakrishna y.s.ramakrishna at
Tue Oct 4 17:39:27 UTC 2011

Sounds good; thanks for running the extra testing!

-- ramki

On 10/04/11 05:47, Bengt Rutisson wrote:
> Ramki,
> On 2011-09-29 10:05, Ramki Ramakrishna wrote:
>> Looks good to me too. Apropos of a comment in one of the CR's in the 
>> trail,
>> would it also be worthwhile to run a test with OpenDS?
> I finally got OpenDS up and running on a Linux x64 machine. I ran a two 
> hour run, which corresponded to 116 iterations. Then I repeated that 
> procedure, so in total I have run 232 iterations of OpenDS without 
> seeing any issues. I have not looked closely at the results (don't 
> really know what to look for), but the harness has not complained about 
> any crashes or hangs and I have not found any hs_err files.
> Is this enough OpenDS testing?
> If yes, then I will push this change as soon as hotspot-gc opens for 
> hs23 stuff for G1.
> Thanks,
> Bengt
>> -- ramki
>> On 9/28/2011 6:42 AM, Jon Masamitsu wrote:
>>> Looks good.
>>> On 09/28/11 05:00, Bengt Rutisson wrote:
>>>> Hi all,
>>>> Could I have a couple of reviews for this small change?
>>>> The code change is very small. I am just enabling the 
>>>> ReduceInitialCardMarks by default for G1. The ReduceInitialCardMarks 
>>>> was disabled since it caused some stability issues. The theory is 
>>>> that those issues arose from the fact that there were bugs that 
>>>> would allocate new objects outside the young gen. These bugs have 
>>>> now been fixed and we should be able to use ReduceInitialCardMarks 
>>>> again.
>>>> Most of the work on this fix has been going in to testing it. I have 
>>>> run the following tests:
>>>> 2 x RefWorkload
>>>> 1 x Full GC test suite
>>>> 7 x GC test suite Dacapo2006
>>>> 16 x GC test suite GCBasher
>>>> 4 x JPRT - All platforms
>>>> 7 x JPRT - Windows only
>>>> I choose the test distribution based on Tony's feedback that the 
>>>> issues related to ReduceInitialCardMarks used to be intermittent in 
>>>> JPRT, and mostly occurred on Windows, and that GCBasher and 
>>>> Dacapo2006 used to have issues with it as well.
>>>> I have not seen any failures in the tests above. I also did not see 
>>>> any regressions in RefWorkLoad. Unfortunately I did not see any 
>>>> improvement either, but I think this change is still worth doing to 
>>>> make G1 behave the same way as the other collectors wrt 
>>>> ReduceInitialCardMarks.
>>>> CR:
>>>> 7005808 G1: re-enable ReduceInitialCardMarks for G1
>>>> This is for hs23, so I will not push it until next week.
>>>> Bengt

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