Request for review (xs) - 8000325

Srinivas Ramakrishna ysr1729 at gmail.com
Sat Jan 5 00:10:00 UTC 2013


Thanks for the perf data, Jon! I'd say that's not too bad.

Out of curiosity, was the diff statistically significant per appropriate
T-test? (i've seen remark pauses show some variance depending on
application and tuning.)

-- ramki

On Fri, Jan 4, 2013 at 3:23 PM, Jon Masamitsu <jon.masamitsu at oracle.com>wrote:

>
>
> On 11/29/2012 3:17 PM, Srinivas Ramakrishna wrote:
>
>> Looks good. Would be great to prominently release-note this change when it
>> appears in a public/GA update/release.
>>
>> Out of curiosity, any perf data on CMS pause time diffs from this change
>> with current NPG?
>>
>
> I ran refworkload server_reference and saw a regression only on
> specjbb2000.  The regression was on the
> remark pauses (as would be expected) and the largest I saw was about 12%.
>  Larger than I would have
> hoped.   The unloading is done serially so maybe things around it got
> faster.
>
> Jon
>
>
>  -- ramki
>>
>> On Thu, Nov 29, 2012 at 9:46 AM, Jon Masamitsu<jon.masamitsu@**oracle.com<jon.masamitsu at oracle.com>
>> >wrote:
>>
>>  This is a change in the default class unloading policy for CMS.
>>>
>>> 8000325:        Change default for CMSClassUnloadingEnabled to true
>>>
>>> http://cr.openjdk.java.net/~****jmasa/8000325/webrev.00/<http://cr.openjdk.java.net/%7E**jmasa/8000325/webrev.00/>
>>> <http:**//cr.openjdk.java.net/%**7Ejmasa/8000325/webrev.00/<http://cr.openjdk.java.net/%7Ejmasa/8000325/webrev.00/>
>>> >
>>>
>>>
>>> With perm gen removal it becomes important for CMS to unload
>>> classes to avoid excessive consumption of native memory for
>>> metadata.
>>>
>>>
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