From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>,
Denys Vlasenko <vda.linux@googlemail.com>,
Oleg Nesterov <oleg@redhat.com>, Rik van Riel <riel@redhat.com>,
X86 ML <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs
Date: Wed, 25 Feb 2015 11:50:20 +0100 [thread overview]
Message-ID: <20150225105020.GF554@gmail.com> (raw)
In-Reply-To: <20150225103701.GA3226@pd.tnic>
* Borislav Petkov <bp@alien8.de> wrote:
> On Tue, Feb 24, 2015 at 04:07:07PM -0800, Andy Lutomirski wrote:
>
> > I'd prefer a different partial solution: encourage
> > everyone to clear the xstate before making syscalls
> > (using e.g. vzeroall). In fact, maybe user code should
> > aggressively clear newly-unused xstate.
>
> We don't trust userspace.
We certainly don't, but in this case it's a performance
optimization detail: if user-space clears unused xstate in
a way that the CPU recognizes it (for example VZEROALL)
then it might get faster context switches.
Thanks,
Ingo
next prev parent reply other threads:[~2015-02-25 10:50 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-20 18:58 [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs Andy Lutomirski
2015-02-20 19:05 ` Borislav Petkov
2015-02-21 9:31 ` Ingo Molnar
2015-02-21 16:38 ` Borislav Petkov
2015-02-21 17:29 ` Borislav Petkov
2015-02-21 18:39 ` Ingo Molnar
2015-02-21 19:15 ` Borislav Petkov
2015-02-21 19:23 ` Ingo Molnar
2015-02-21 21:36 ` Borislav Petkov
2015-02-22 8:18 ` Ingo Molnar
2015-02-22 8:22 ` Ingo Molnar
2015-02-22 10:48 ` Borislav Petkov
2015-02-22 12:50 ` Borislav Petkov
2015-02-22 12:57 ` Ingo Molnar
2015-02-22 13:21 ` Borislav Petkov
2015-02-22 0:34 ` Maciej W. Rozycki
2015-02-22 2:18 ` Andy Lutomirski
2015-02-22 11:06 ` Borislav Petkov
2015-02-23 1:45 ` Rik van Riel
2015-02-23 5:22 ` Andy Lutomirski
2015-02-23 12:51 ` Rik van Riel
2015-02-23 15:03 ` Borislav Petkov
2015-02-23 15:51 ` Rik van Riel
2015-02-23 18:06 ` Borislav Petkov
2015-02-23 21:17 ` Maciej W. Rozycki
2015-02-23 21:21 ` Rik van Riel
2015-02-23 22:14 ` Linus Torvalds
2015-02-24 0:56 ` Maciej W. Rozycki
2015-02-24 0:59 ` Andy Lutomirski
2015-02-23 22:27 ` Maciej W. Rozycki
2015-02-23 23:44 ` Andy Lutomirski
2015-02-24 2:14 ` Maciej W. Rozycki
2015-02-24 2:31 ` Andy Lutomirski
2015-02-24 14:43 ` Rik van Riel
2015-02-21 18:34 ` Ingo Molnar
2015-02-23 14:59 ` Oleg Nesterov
2015-02-23 15:11 ` Borislav Petkov
2015-02-23 15:53 ` Rik van Riel
2015-02-23 18:40 ` Oleg Nesterov
2015-02-24 19:15 ` Denys Vlasenko
2015-02-25 0:07 ` Andy Lutomirski
2015-02-25 10:37 ` Borislav Petkov
2015-02-25 10:50 ` Ingo Molnar [this message]
2015-02-25 10:45 ` Ingo Molnar
2015-02-25 17:12 ` Some results (was: Re: [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs) Borislav Petkov
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