Request for review (xs) - 8000325

[Jon Masamitsu]

Yes, the differences were statistically significant.

Jon


On 1/4/2013 4:10 PM, Srinivas Ramakrishna wrote:
> 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.
>>>>
>>>>