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

John Cuthbertson john.cuthbertson at
Thu Sep 29 16:20:45 UTC 2011

Hi Bengt, Ramki

Funny this should be brought up - I just placed a copy on the /export 
directory of my workstation (so that it could be accessed from any of 
the lab machines) to reproduce the missing parallel other time. I'll 
send some instructions.


On 09/29/11 01:42, Bengt Rutisson wrote:
> 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?
>>>> 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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