RFR: 8072070: Improve interpreter stack banging [v5]

[Aleksey Shipilev]

On Fri, 11 Feb 2022 11:29:12 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> Seems like Power is not affected by this TLB / Cache bottleneck. We use 64k pages and typically 2 store instructions for banging. On the other side, I think it's a good thing to avoid touching any storage which we don't need. So, we could overwork the PPC64 implementation, too (optionally). Or wait until more experiments have been made.

Yes, larger VM pages mean fewer addresses to touch. OTOH, in my related experiments with removing the stack banging on compiled entry whatsoever, we seem to redeem single-digit percent improvements, even though we only touch one location far away. 

Anyhow, I think a good plan is to wait and see if this x86 pilot change runs into any interesting problems, before translating it to other architectures.

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PR: https://git.openjdk.java.net/jdk/pull/7247