On Wed, 29 May 2024 11:33:40 GMT, Doug Lea <[email protected]> wrote:
>> This set of changes address causes of poor utilization with small numbers of
>> cores due to overly aggressive contention avoidance. A number of further
>> adjustments were needed to still avoid most contention effects in
>> deployments with large numbers of cores
>
> Doug Lea has updated the pull request with a new target base due to a merge
> or a rebase. The incremental webrev excludes the unrelated changes brought in
> by the merge/rebase. The pull request contains 41 additional commits since
> the last revision:
>
> - Merge branch 'openjdk:master' into JDK-8322732
> - Add test for utilization with interdependent tasks
> - Un-misplace onSpinWait call
> - Adjust control flow
> - Reduce memory stalls
> - Merge branch 'openjdk:master' into JDK-8322732
> - More performance tradoffs
> - Address review comments
> - Merge branch 'openjdk:master' into JDK-8322732
> - Repack some fields; adjust control flow
> - ... and 31 more: https://git.openjdk.org/jdk/compare/1dc80514...cf5fe55c
src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 2094:
> 2092: if (((p = w.phase) & IDLE) != 0)
> 2093: p = awaitWork(w, delay); // block, drop, or
> exit
> 2094: }
I'm presuming the code below would be equivalent but avoid calculating the
delay unless w.phase is IDLE?
Suggestion:
if ((p & IDLE) != 0 && ((p = w.phase) & IDLE) != 0) {
long delay = (((qc & RC_MASK) > 0L) ? 0L :
(w.source != INVALID_ID) ? keepAlive :
TIMEOUT_SLOP); // minimal delay if cascade
p = awaitWork(w, delay); // block, drop, or exit
}
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/19131#discussion_r1618980694
