Re: [PATCH, nvptx, 1/2] Reimplement libgomp barriers for nvptx

[Thomas Schwinge <thomas@codesourcery.com>]

Hi!

On 2022-12-16T15:51:35+0100, Tom de Vries via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> On 9/21/22 09:45, Chung-Lin Tang wrote:
>> I had a patch submitted earlier, where I reported that the current way
>> of implementing
>> barriers in libgomp on nvptx created a quite significant performance
>> drop on some SPEChpc2021
>> benchmarks:
>> https://gcc.gnu.org/pipermail/gcc-patches/2022-September/600818.html

Also: my 2022-03-17 report in <https://gcc.gnu.org/PR99555>
"[OpenMP/nvptx] Execution-time hang for simple nested OpenMP 'target'/'parallel'/'task' constructs":
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99555#c13>.

>> This patch has been tested on x86_64/powerpc64le with nvptx offloading,
>> using libgomp, ovo, omptests,
>> and sollve_vv testsuites, all without regressions. Also verified that
>> the SPEChpc 2021 521.miniswp_t
>> and 534.hpgmgfv_t performance regressions that occurred in the GCC12
>> cycle has been restored to
>> devel/omp/gcc-11 (OG11) branch levels.

I'm happy to confirm that this also does resolve the PR99555 issue
mentioned above, so please do reference PR99555 in the commit log.

>> Is this okay for trunk?

> Yes, LGTM, please apply (after the other one).
>
> Thanks for addressing this.

Thanks, Chung-Lin and Tom!

>> (also suggest backporting to GCC12 branch, if performance regression can
>> be considered a defect)
>
> That's ok, but wait a while after applying on trunk before doing that,
> say a month.


Grüße
 Thomas
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