Integrated: 8272807: Permit use of memory concurrent with pretouch

[Kim Barrett]

On Fri, 4 Feb 2022 10:47:18 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> [Trying again, after a couple previous proposals.]
> 
> Please review this change to os::pretouch_memory to permit use of the memory
> being pretouched concurrently with the pretouch operation.  This will allow
> future changes that can make use of such overlap.
> 
> Testing:
> mach5 tier1-3 with -XX:+AlwaysPreTouch.
> 
> Verified no performance impact by comparing startup times with Epsilon GC and
> -XX:+AlwaysPretouch on a large enough heap that the pretouch takes a
> significant amount of time.  Tested on both linux-x64 and linux-aarch64.
> 
> None of these test concurrent use; that will wait for future changes that use
> the new feature.

This pull request has now been integrated.

Changeset: 072e7b4d
Author:    Kim Barrett <kbarrett at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/072e7b4da0449ab7c1ab1ba0cfbb3db233823e7c
Stats:     28 lines in 2 files changed: 18 ins; 1 del; 9 mod

8272807: Permit use of memory concurrent with pretouch

Reviewed-by: shade, stuefe

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PR: https://git.openjdk.java.net/jdk/pull/7343