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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 27 Feb 2019 11:41:31 -0800
Message-ID: <CAHk-=wgfx6rUXpH16A9OAyEEh9nf18pk9mL7Wkz5b6eDc9dPpA@mail.gmail.com>
Subject: Re: [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()
To:     Nadav Amit <namit@vmware.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Lutomirski <luto@kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Matthew Wilcox <willy@infradead.org>
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On Wed, Feb 27, 2019 at 9:57 AM Nadav Amit <namit@vmware.com> wrote:
>
> I=E2=80=99ll have a look at some specific function assembly, but overall,=
 the =E2=80=9C+m=E2=80=9D
> approach might prevent even more code optimizations than the =E2=80=9Cvol=
atile=E2=80=9D one.

Ok, that being the case, let's forget that patch.

I still wonder about the added volatiles to the xadd/cmpxchg cases,
which already had the "memory" clobber which should make the volatile
immaterial..

                 Linus