8034761: Remove the do_code_roots parameter from process_strong_roots

Stefan Karlsson stefan.karlsson at oracle.com
Wed Feb 12 23:51:37 PST 2014


On 13/02/14 03:14, Jon Masamitsu wrote:
> Stefan,
>
> I understand now that the same work is being
> done (maybe in a different place) and that
> the  amount of extra work being
> done (the call to test_set_oops_do_mark())
> will scale with the number of nmethods.
>
> Is that correct?

Yes, that's correct.

StefanK
>
> Jon
>
> On 2/12/2014 11:40 AM, Jon Masamitsu wrote:
>>
>> On 2/12/2014 1:43 AM, Stefan Karlsson wrote:
>>> Hi all,
>>>
>>> Please, review this patch to remove the do_code_roots parameter from 
>>> SharedHeap::process_strong_roots.
>>>
>>> The changes done are:
>>> - Change the code to rely on the ScannningOption so parameter 
>>> instead of do_code_roots.
>>> - Change GenMarkSweep and G1MarkSweep to adjust the code roots with 
>>> the help of process_strong_roots instead of doing it as a separate 
>>> phase after process_strong_roots.
>>> - Removed the unused FalseClosure.
>>>
>>> After this patch the adjust phase of the GenMarkSweep and 
>>> G1MarkSweep will use the generic code in process_strong_roots, which 
>>> mark/claim the nmethods before they are processed. Before the patch 
>>> these two Serial Old GC adjust phases skipped the mark/claim part. 
>>> No noticeable Serial Old GC time increases were found when this 
>>> patch was performance tested.
>>
>> Does this mean ("adjust phase ...") that the "mark/claim"  does not  
>> have any affect
>> on later processing?  Or actually does nothing (even though the closures
>> are applied)?  Which benchmarks did you use for performance testing?
>>
>> Jon
>>>
>>> This cleanup is needed/wanted for G1 Class Unloading.
>>>
>>> Webrev:
>>> http://cr.openjdk.java.net/~stefank/8034761/webrev.00/
>>>
>>> RFE:
>>> https://bugs.openjdk.java.net/browse/JDK-8034761
>>>
>>> thanks,
>>> StefanK
>>
>

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