RFC: Accept embedded oops barriers to alleviate final mark time

[Aleksey Shipilev]

Sure. Handle this as you see fit! Over and out.

-Aleksey

On 06/16/2017 10:07 PM, Roman Kennke wrote:
> The results are cool.
> 
> The patch is not trivial enough to quickly check for correctness, or
> else hide everything behind a flag (at least not afaics) ;-) I'll take a
> closer look next week, when I am back, if that is ok with you.
> 
> Thanks, and enjoy your vacation!
> 
> Roman
> 
> Am 16.06.2017 um 21:14 schrieb Aleksey Shipilev:
>> Hi,
>>
>> This is my experimental patch for accepting barriers in the code cache, *and*
>> avoiding the evacuation work at the pause. It is dirty, and maybe incorrect, but
>> it passes hotspot_gc_shenandoah, and provides nice improvements for final mark
>> pause time. The overheads for emitting the barrier for constants is hard to
>> quantify before Roland fixes up the compiler bugs around it. Throwing the patch
>> out for the record, while I am going on vacation :)
>>
>> Webrev:
>>   http://cr.openjdk.java.net/~shade/shenandoah/codecache-barriers/webrev.01/
>>
>> GC stats before/after on some workloads:
>>   http://cr.openjdk.java.net/~shade/shenandoah/codecache-barriers/perf.txt
>>
>> Init evac times, and sometimes final mark times are down to 100-500 us range!
>>
>> Thanks,
>> -Aleksey
>>
>>
>