Re: [PATCH AUTOSEL 5.15 11/12] x86/barrier: Do not serialize MSR accesses on AMD

From: Pavel Machek
Date: Fri Nov 29 2024 - 16:27:33 EST


Hi!

> > > - Serious issues as reported by a user of a distribution kernel may also
> > > be considered if they fix a notable performance or interactivity issue.
> > >
> > > It sounds like what's going on here, no?
> >
> > Is it? I'd not expect this to be visible in anything but
> > microbenchmarks. Do you have user reports hitting this?
> >
> > It is not like this makes kernel build 10% slower, is it?
>
> On Fri, Nov 29, 2024 at 10:30:11AM +0100, Erwan Velu wrote:
> > This patch greatly impacts servers on production with AMD systems that
> > have lasted since 5.11, having it backported really improves systems
> > performance.
> > Since this patch, I can share that our database team is no longer
> > paged during the night, that's a real noticeable impact.

Ok, looks like I misjudged the performance impact, sorry for the
noise.

Best regards,
Pavel

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