RFR: 8154343: Make SATB related code available to other GCs

Jon Masamitsu jon.masamitsu at oracle.com
Fri Apr 15 21:30:27 UTC 2016

On 4/15/2016 12:17 PM, Roman Kennke wrote:
> I just noticed that I made the patch against the jdk9 repository,
> instead of jdk9-dev. There was a small change to make to
> require_marking()/retain_entry(). The updated webrev is here:
> http://cr.openjdk.java.net/~rkennke/jdk-8154343/webrev.01/
> And I also forgot to post a link to the jira entry:
> https://bugs.openjdk.java.net/browse/JDK-8154343
> Please let me know what you think, and if I can commit it. Thanks!


You're aware of jprt?  The tool that Oracle uses to build hotspot 
patches on all platforms,
do a minimum amount of testing, and then does the commit?  For shared code
such as in your patch, it is always used.  Sorry if I'm stating old news 
but I wasn't
sure what to make of your request to commit (yourself).

jprt is an internal tool and externally contributed patches are handed 
off to
an Oracle sponsor to submit.


> Roman
> Am Freitag, den 15.04.2016, 19:31 +0200 schrieb Roman Kennke:
>> Hi,
>> I propose the following patch to move the SATB queue code from gc/g1
>> into gc/shared. The issue is that we (Shenandoah devs) are using it
>> too, and get a mess everytime we merge upstream changes. And besides,
>> it's referenced from a couple of places.
>> Some details:
>> - satbMarkQueue.[hpp|cpp] and ptrQueue.[hpp|cpp] are moved over to
>> gc/shared
>> - The only G1 reference in that code was in the filter() method. I
>> moved requires_marking() into G1CollectedHeap, and it's called via a
>> templated filter_impl(), this should avoid *any* potential
>> performance
>> impact. Reusing that in another GC (e.g. Shenandoah) would require to
>> implement an non-virtual inline require_marking() method in the
>> CollectedHeap subclass, and add a driver clause to filter(), so that
>> the compiler generates the templated filter_impl().
>> - enqueue() has been moved from G1SATBCardTableModRefBS into
>> SATBMarkQueue, it's still a static method.
>> - SATB related globals have been moved into globals.hpp, in the GC
>> section, and got their 'G1' prefix removed. I hope that's ok?
>> The complete set of changes is here:
>> http://cr.openjdk.java.net/~rkennke/jdk-8154343/webrev.00/
>> Any thoughts? Ok to commit&push?
>> Best regards,
>> Roman

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