ACK: [SRU][N:linux-aws][PATCH 0/2] Backport Perf patchset to address Linux kernels performance regression

[Kuba Pawlak]

On 2.04.2025 16:48, Philip Cox wrote:
> BugLink: https://bugs.launchpad.net/bugs/2106004
>
> SRU Justification:
>
> Impact]
>
> A significant regression (between 0.5x and 0.2x) in benchmark results has been noticed on Stream when profiled with APerf. On further investigation it has been identified that the regression is coming from the Linux Perf subsystem which is used by APerf to collect PMU metrics and Flamegraph profiling data.
>
> The regression first occured between v6.1 and v6.2 of the upstream linux kernel.
>
> [Fix]
>
> It has been identified this patchset: https://lore.kernel.org/lkml/20240111204348.669673-1-namhyung@kernel.org/ was merged in v6.10 to fix the performance regression.
>
> These changes correspond to upstream commits:
> f38628b06c36
> 0259bf63f71e
>
> [Test Plan]
>
> AWS tested
>
> [Where problems could occur]
>
> The changes are fairly narrow in scope, and changes how the PMU checks frequencies and throttles.  As this is fixing a regression if a system is relying on the behaviour present after the regression was introduced, and before it is fixed, it may have strange side effects.
>
> The other area that this may have problems is if the stable branches bring in changes to the PMU throttling code that does not have this fix corrected, strange behaviour may result, or merge conflicts may occur.
>
>
> [Other Info]
> SF #00407096
>
> --
>
>
Acked-by: Kuba Pawlak <kuba.pawlak at canonical.com>
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