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

Stefan Johansson stefan.johansson at oracle.com
Tue Feb 4 16:08:17 UTC 2014

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 this.

> /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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