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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 26 May 2023 13:37:15 -0700
Message-ID: <CAHk-=wibWdTp-kdCKc-F3d4aVcHO40qqoxoATG+KhVivYE0TqA@mail.gmail.com>
Subject: Re: x86 copy performance regression
To:     Eric Dumazet <edumazet@google.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>
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On Fri, May 26, 2023 at 11:33=E2=80=AFAM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Anyway, I guess *this* avoids all issues. It creates an extra jump to
> a jump for the case where the CPU doesn't have ERMS, but I guess we
> don't really care about those CPUs anyway.

Well, I'm obviously wrong, because my very own CPU (AMD Zen 2) doesn't do E=
RMS.

But the extra 'jmp' doesn't seem to appreciably matter, so I guess I
don't care. It does show up in profiles, but only barely.

I've committed and pushed out the fix.

               Linus