RFR (round 2), JEP-318: Epsilon GC

Jini George jini.george at oracle.com
Wed May 9 17:18:08 UTC 2018


Hi Aleksey,

(Not a review). Do you plan to put in any basic serviceability agent 
(SA) support for this?

Thank you,
Jini.

On 5/7/2018 8:28 PM, Aleksey Shipilev wrote:
> Hi,
> 
> This is round 2 code review for Epsilon GC changes.
> 
> JEP, targeted to 11:
>    http://openjdk.java.net/jeps/318
>    (you can find links to binary builds and sandbox locations there)
> 
> Webrev:
>    http://cr.openjdk.java.net/~shade/epsilon/webrev.06/
> 
> Notes:
> 
>    *) See how the whole thing is almost completely isolated to hotspot/share/gc, without having
> arch-specific mess -- thanks to GC interface work done over last years. The only leftover is the
> change in graphKit.cpp that should go away after C2 barriers modularization [1] is complete;
> 
>    *) Recently added GC TLD facility and Elastic TLABs feature enables Epsilon to be more streamlined
> in figuring out the TLAB sizes;
> 
>    *) Conditional GC compilation is supported. ISVs may choose not to build Epsilon, if they do not
> want to extend whatever small notion of support that comes with experimental VM option [2].
> 
>    *) Half of the webrev are Epsilon-specific tests. They take ~30s in release and ~60s in fastdebug
> on my desktop. They are not in tier1, so smoke testing time is not affected;
> 
> 
> Builds:
>      server X {x86_64, x86_32, aarch64, arm32, ppc64le, s390x}
>        zero X {x86_64}
>     minimal X {x86}
> 
> Testing: gc/epsilon on x86_64
> 
> Thanks,
> -Aleksey
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8202377
> [2] http://hg.openjdk.java.net/jdk/jdk/file/3661f31c6df4/src/hotspot/share/runtime/globals.hpp#l150
> 


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