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

Bengt Rutisson bengt.rutisson at oracle.com
Thu Sep 29 01:42:02 PDT 2011


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?

Thanks, Ramki. Since I have a few days before I can push anyway I'll run 
OpenDS as well.

Do you know of any instructions on how to set up and run OpenDS locally? 
If not I'll try to use UTE to run it on one of the machines in the 
former Sun-network.

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?
>>>
>>> http://cr.openjdk.java.net/~brutisso/7005808/webrev/
>>>
>>> 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
>>> http://monaco.us.oracle.com/detail.jsf?cr=7005808
>>>
>>> This is for hs23, so I will not push it until next week.
>>>
>>> Bengt



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