RFR: 8316180: Thread-local backoff for secondary_super_cache updates [v6]

[Amit Kumar]

On Wed, 27 Sep 2023 18:25:02 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> I see the following disclaimer in the description:
>>> Work in progress, submitting for broader attention.
>> 
>> What are next steps and, more broadly, what's left to get the PR finalized? Especially, it's not clear how much performance testing it went through so far.
>
>> What are next steps and, more broadly, what's left to get the PR finalized? Especially, it's not clear how much performance testing it went through so far.
> 
> I was waiting on Derek White to publish their benchmarks, so that we can decide reasonable defaults. While it seems too early to run larger scale benchmarks, feel free to give it a spin.

Hi @shipilev,

Please include s390 patch from here:

[s390_port.patch](https://github.com/openjdk/jdk/files/12882890/s390_port.patch)


Benchmark: Z15 Machine, with 64 CPUs

-XX:SecondarySuperMissBackoff=0
Benchmark                        Mode  Cnt     Score       Error  Units
SecondarySuperCache.contended    avgt   15  10655.113 ? 6148.685  ns/op
SecondarySuperCache.uncontended  avgt   15    107.9   ?   54.109  ns/op

-XX:SecondarySuperMissBackoff=10
Benchmark                        Mode  Cnt    Score       Error  Units
SecondarySuperCache.contended    avgt   15  2541.671 ? 1048.361  ns/op
SecondarySuperCache.uncontended  avgt   15   120.107 ?   63.345  ns/op
-XX:SecondarySuperMissBackoff=100

Benchmark                        Mode  Cnt   Score      Error  Units
SecondarySuperCache.contended    avgt   15  662.473 ? 139.208  ns/op
SecondarySuperCache.uncontended  avgt   15   79.371 ?  40.232  ns/op

-XX:SecondarySuperMissBackoff=1000
Benchmark                        Mode  Cnt   Score     Error  Units
SecondarySuperCache.contended    avgt   15  248.292 ? 77.175  ns/op
SecondarySuperCache.uncontended  avgt   15   87.333 ? 35.103  ns/op

-XX:SecondarySuperMissBackoff=10000
Benchmark                        Mode  Cnt   Score    Error  Units
SecondarySuperCache.contended    avgt   15  139.901 ? 44.83  ns/op
SecondarySuperCache.uncontended  avgt   15   90.872 ? 31.791 ns/op

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PR Comment: https://git.openjdk.org/jdk/pull/15718#issuecomment-1759621237