RFR: 8033426: Scale initial NewSize using NewRatio if not set on command line

Stefan Johansson stefan.johansson at oracle.com
Fri Feb 7 12:31:00 UTC 2014

Hi again,

I've looked at how to test this in a good way and come up with this 
simple unit test to verify the basic rules for NewSize. This test 
doesn't strive to cover all possible combinations of how NewSize 
interacts with other flags, but instead focus on testing that a few well 
defined cases work as expected without duplicating a lot of logic from 
the product.

Please review the updated webrev:


On 2014-02-04 17:08, Stefan Johansson wrote:
> Hi Jesper,
> On 2014-02-03 17:50, Jesper Wilhelmsson wrote:
>> Hi Stefan,
>> Have you looked at how this change plays with the ergonomics for 
>> NewSize in Arguments::set_cms_and_parnew_gc_flags()? That code will 
>> also use NewRatio to scale NewSize, but if running with a large 
>> CMSYoungGenPerWorker it may end up with a larger NewSize. Looks like 
>> your change will handle it well, but it would be nice with some test 
>> to verify it going forward.
> I hadn't looked into this in depth but I took a look now and it seems 
> to be handled well as you say. If the NewSize is set to something the 
> new code will never shrink it.
> Regarding testing, Erik H will soon push his fixes for one of the 
> HeapSize tests. I will make sure nothing is broken with the improved 
> test and also see if we can add some test case to it to test the NewSize.
>> Anyways, looks good to me.
>> Ship it!
> Thanks for reviewing 
> thishttp://cr.openjdk.java.net/~sjohanss/8033426/webrev.01/.
> Stefan
>> /Jesper
>> Stefan Johansson skrev 3/2/14 4:40 PM:
>>> Hi,
>>> Can I have a couple of reviews for this enhancement:
>>> https://bugs.openjdk.java.net/browse/JDK-8033426
>>> Webrev:
>>> http://cr.openjdk.java.net/~sjohanss/8033426/webrev.00/
>>> Summary:
>>> Currently the initial young generation size is the same as the 
>>> minimum. If not
>>> using large pages this will be 1.5M for the default collector 
>>> regardless of how
>>> large the whole heap is. The proposed change is to scale the initial 
>>> young size
>>> the same way the maximum young size is scaled, using the NewRatio 
>>> parameter.
>>> Note:
>>> This change has been out on review as part of the fix for 
>>> JDK-8028498, but after
>>> discussions we have decided take another approach for that bug.
>>> Testing:
>>> * JPRT
>>> * GC tests in jtreg
>>> Thanks,
>>> Stefan

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