From: Mateusz Guzik <mjguzik@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bp@alien8.de
Subject: Re: [PATCH v2] x86: bring back rep movsq for user access on CPUs without ERMS
Date: Sun, 3 Sep 2023 22:48:58 +0200 [thread overview]
Message-ID: <20230903204858.lv7i3kqvw6eamhgz@f> (raw)
In-Reply-To: <CAHk-=wg6bzTdQHSsswHPYFUbb1DfszyWTZ97hZv7bYxaNHVkHw@mail.gmail.com>
On Sun, Sep 03, 2023 at 01:08:03PM -0700, Linus Torvalds wrote:
> On Sun, 3 Sept 2023 at 11:49, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > So I have no idea why you claim that "currently they have no choice".
> > glibc is simply being incredibly stupid, and using newfstatat() for no
> > good reason.
>
> Do you have any good benchmark that shows the effects of this?
>
> And if you do, does the attached patch (ENTIRELY UNTESTED!) fix the
> silly glibc mis-feature?
>
"real fstat" is syscall(5, fd, &sb).
Sapphire Rapids, will-it-scale, ops/s
stock fstat 5088199
patched fstat 7625244 (+49%)
real fstat 8540383 (+67% / +12%)
It dodges lockref et al, but it does not dodge SMAP which accounts for
the difference.
next prev parent reply other threads:[~2023-09-03 20:49 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 14:03 [PATCH v2] x86: bring back rep movsq for user access on CPUs without ERMS Mateusz Guzik
2023-08-30 16:50 ` Linus Torvalds
2023-08-30 20:00 ` Linus Torvalds
2023-09-01 15:20 ` Mateusz Guzik
2023-09-01 15:29 ` Linus Torvalds
2023-09-03 18:49 ` Linus Torvalds
2023-09-03 19:14 ` Linus Torvalds
2023-09-03 20:08 ` Linus Torvalds
2023-09-03 20:48 ` Mateusz Guzik [this message]
2023-09-03 20:57 ` Linus Torvalds
2023-09-03 21:06 ` Mateusz Guzik
2023-09-03 21:08 ` Linus Torvalds
2023-09-03 21:18 ` Mateusz Guzik
2023-09-03 23:28 ` Al Viro
2023-09-03 20:58 ` Mateusz Guzik
2023-09-03 21:05 ` Linus Torvalds
2023-09-03 21:48 ` Ingo Molnar
2023-09-03 22:34 ` Linus Torvalds
2023-09-03 23:15 ` Mateusz Guzik
2023-09-04 3:07 ` Linus Torvalds
2023-09-04 3:17 ` Linus Torvalds
2023-09-04 6:03 ` Mateusz Guzik
2023-09-04 17:28 ` Linus Torvalds
2023-09-05 20:41 ` Mateusz Guzik
2023-09-06 0:16 ` Linus Torvalds
2023-09-06 4:11 ` Mateusz Guzik
2023-09-01 13:33 ` David Laight
2023-09-01 15:28 ` Mateusz Guzik
2023-09-03 20:42 ` David Laight
2023-09-10 10:53 ` Mateusz Guzik
2023-09-11 10:37 ` David Laight
2023-09-12 18:48 ` Linus Torvalds
2023-09-12 19:41 ` David Laight
2023-09-12 20:48 ` Linus Torvalds
2023-09-13 8:25 ` David Laight
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