RFR: 8280056: gtest/LargePageGtests.java#use-large-pages failed "os.release_one_mapping_multi_commits_vm" [v4]

[Gerard Ziemski]

On Mon, 27 Nov 2023 16:22:55 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Can we guard (using `#if`, for example) this test to run only in Windows platform?
>
>> I wrote this originally (I believe) because of a very real issue where, on Windows, we would allocate memory in stripes for different NUMA nodes, and then later release the memory. IIRC, this just released the first stripe, so the rest stayed allocated (os::release_memory(p, size) called VirtualFree(MEM_RELEASE, p), ignoring the size parameter).
>> 
>> Fixing that was not trivial - we changed os::release_memory to, if called over multiple reservations, release them all. It would query all existing reservations in that area with VirtualQuery. That stuff is intricate and it can fail, so a regression test makes actually a lot of sense.
> 
> Can we add this reasoning to the test please, so we know in the future why we are doing this?

> Can we guard (using `#if`, for example) this test to run only in Windows platform?

Since we must do it anyhow on Windows with NUMA, I feel like we might as well deploy it on all platforms, just in case, but it is a valid suggestion.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16240#discussion_r1406426311