Pls review 6887571

[Paul Hohensee]

You're right, they should migrate back.  If there's a need for them to 
diverge
in the future, we can split them back out then.

Thanks,

Paul

Y.S.Ramakrishna at Sun.COM wrote:
> Hi Paul --
>
> Looks good (and about time too!).
> Should the parameters whose defaults are now
> uniform across platforms migrate back to globals.hpp
> from their current lobals_*.hpp locations? Or do you
> see the need for continuing to keep them in platform-specific
> globals_*.hpp?
>
> -- ramki
>
> On 10/02/09 07:32, Paul Hohensee wrote:
>> 6887571: Increase default heap config sizes
>>
>> Webrev at
>>
>> http://cr.openjdk.java.net/~phh/6887571/webrev.00/
>>
>>  From the CR description:
>>
>> The default client vm heap config since ~2000 has been the equivalent of
>>
>> -Xmx64m -XX:OldSize=4m -XX:NewSize=2m -XX:NewRatio=8
>> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=15
>>
>> for sparc32, and
>>
>> -Xmx64m -XX:OldSize=4m -XX:NewSize=1m -XX:NewRatio=12
>> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=15
>>
>> for x86.  OldSize and NewSize are the initial committed sizes of the old
>> and young gens respectively.  A full gc is required to increase the 
>> committed
>> size of the old gen.
>>
>> At the time, 64m was half of the 128m of memory typically available 
>> on high-end
>> desktops, many client applications were satisfied with small heaps 
>> (hence the
>> low -Xms value), and gc times were such that the young gen had to be 
>> fairly small
>> in order to minimize pause times.
>>
>> Since that time, low end desktops and laptops, as well as netbooks 
>> and smartbooks,
>> typically come with 256m, client applications have become much more 
>> "server-like",
>> and we've realized that small young gen sizes increase the frequency 
>> of young gcs
>> and the amount of transient data promoted to the old gen to levels 
>> that noticeably
>> impact startup and steady-state performance, principally by provoking 
>> full GCs.
>> We also note that young gen collection times are proportional to the 
>> total survivor
>> size rather than young gen size and that small (in absolute terms) 
>> survivor spaces
>> cause promotion of transient objects, thereby eventually provoking 
>> unnecessary
>> full GCs.
>>
>> This change make the default heap config
>>
>> -Xmx128m -XX:OldSize=14m -XX:NewSize=4m -XX:NewRatio=2
>> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=15
>>
>> I.e., it leaves SurvivorRatio and MaxTenuringThreshold alone, but 
>> increases absolute
>> survivor space size significantly.  We still want as many objects to 
>> die in the young
>> gen as possible, so MaxTenuringThreshold reamins at maximum.  
>> NewRatio is
>> set to the server default of 2, thereby increasing reducing the 
>> number of young collections.
>>
>> JavaFX startup benchmark runs show an almost 11% improvement, while 
>> generic
>> client startup benchmark runs show up to 14% improvement.  Footprint 
>> increases
>> somewhat, ranging from 2% for noop to 37% for netbeans.
>>
>> Thanks,
>>
>> Paul
>>
>