From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Andrew Lutomirski <luto@kernel.org>
Cc: riel@surriel.com, dave.hansen@linux.intel.com,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>
Subject: Re: Lazy FPU restoration / moving kernel_fpu_end() to context switch
Date: Fri, 15 Jun 2018 22:33:47 +0200 [thread overview]
Message-ID: <CAHmME9qhmSVNBq_GnkYrGU-PPEX9Fk0yiGktsCeEXo+LTB9KPg@mail.gmail.com> (raw)
In-Reply-To: <CALCETrU+2mBPDfkBz1i_GT1EOJau+mzj4yOK8N0UnT2pGjiUWQ@mail.gmail.com>
On Fri, Jun 15, 2018 at 8:32 PM Andy Lutomirski <luto@kernel.org> wrote:
> quite in the form you imagined. The idea that we've tossed around is
> to restore FPU state on return to user mode. Roughly, we'd introduce
> a new thread flag TIF_FPU_UNLOADED (name TBD).
> prepare_exit_to_usermode() would notice this flag, copy the fpstate to
> fpregs, and clear the flag. (Or maybe exit_to_usermode_loop() -- No
> one has quite thought it through, but I think it should be outside the
> loop.) We'd update all the FPU accessors to understand the flag.
Yes! This is exactly what I was thinking. Then those calls to begin()
and end() could be placed as close to the actual FPU usage as
possible.
next prev parent reply other threads:[~2018-06-15 20:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-15 13:11 Lazy FPU restoration / moving kernel_fpu_end() to context switch Jason A. Donenfeld
2018-06-15 16:25 ` Thomas Gleixner
2018-06-15 18:33 ` Brian Gerst
2018-06-15 19:34 ` Peter Zijlstra
2018-06-15 20:30 ` Jason A. Donenfeld
2018-06-18 9:44 ` Peter Zijlstra
2018-06-18 15:25 ` Jason A. Donenfeld
2018-06-15 18:31 ` Andy Lutomirski
2018-06-15 18:40 ` Rik van Riel
2018-06-15 18:41 ` Dave Hansen
2018-06-15 18:49 ` Andy Lutomirski
2018-06-15 18:48 ` Dave Hansen
2018-06-15 18:53 ` Andy Lutomirski
2018-06-15 20:27 ` Jason A. Donenfeld
2018-06-15 20:48 ` Jason A. Donenfeld
2018-06-19 11:43 ` David Laight
2018-06-19 13:08 ` Thomas Gleixner
2018-06-15 20:33 ` Jason A. Donenfeld [this message]
2018-06-15 20:42 ` Dave Hansen
2018-06-15 20:52 ` Andy Lutomirski
2018-06-15 20:56 ` Rik van Riel
2018-07-11 16:28 ` Sebastian Andrzej Siewior
2018-07-11 20:10 ` Rik van Riel
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