RFR: 8294775: Shenandoah: reduce contention on _threads_in_evac [v2]
Nick Gasson
ngasson at openjdk.org
Wed Oct 19 17:05:26 UTC 2022
> The idea here is to reduce contention on the shared `_threads_in_evac` counter by splitting its state over multiple independent cache lines. Each thread hashes to one particular counter based on its `Thread*`. This helps improve throughput of concurrent evacuation where many Java threads may be attempting to update this counter on the load barrier slow path.
>
> See this earlier thread for details and SPECjbb results: https://mail.openjdk.org/pipermail/shenandoah-dev/2022-October/017494.html
>
> Also tested `hotspot_gc_shenandoah` on x86 and AArch64.
Nick Gasson has updated the pull request incrementally with one additional commit since the last revision:
Refactor
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/10573/files
- new: https://git.openjdk.org/jdk/pull/10573/files/2303fbed..14cec5ed
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=10573&range=01
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=10573&range=00-01
Stats: 184 lines in 3 files changed: 109 ins; 45 del; 30 mod
Patch: https://git.openjdk.org/jdk/pull/10573.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/10573/head:pull/10573
PR: https://git.openjdk.org/jdk/pull/10573
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