From: Rik van Riel <riel@redhat.com>
To: Dave Hansen <dave.hansen@linux.intel.com>, linux-kernel@vger.kernel.org
Cc: x86@kernel.org, tglx@linutronix.de, pbonzini@redhat.com,
mingo@redhat.com, luto@kernel.org, hpa@zytor.com, bp@suse.de
Subject: Re: [PATCH RFC 4/5] x86,fpu: lazily skip FPU restore when still loaded
Date: Mon, 03 Oct 2016 17:02:57 -0400 [thread overview]
Message-ID: <1475528577.4622.11.camel@redhat.com> (raw)
In-Reply-To: <57F2C467.5060007@linux.intel.com>
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On Mon, 2016-10-03 at 13:49 -0700, Dave Hansen wrote:
> On 10/03/2016 01:22 PM, Rik van Riel wrote:
> >
> > >
> > > >
> > > > What are the preempt rules with this thing? This needs to be
> > > > called
> > > > in preempt-disabled contexts, right?
> > Indeed, all the FPU context switching code needs
> > to be called in preempt-disabled contexts.
> >
> > You do not want to get preempted halfway through
> > saving or restoring floating point registers.
> OK, cool, that's what I expected. Could you just add a comment about
> it
> to make it clear that it's also the case for this new
> fpu_lazy_skip_restore() helper?
Turns out the code already has an old
fpu_want_lazy_restore(), which is what
I will use instead :)
I will add documentation about preemption
in places where it is necessary.
--
All rights reversed
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next prev parent reply other threads:[~2016-10-03 21:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-01 20:31 [PATCH RFC 0/5] x86,fpu: make FPU context switching much lazier riel
2016-10-01 20:31 ` [PATCH RFC 1/5] x86,fpu: split prev/next task fpu state handling riel
2016-10-01 23:26 ` Andy Lutomirski
2016-10-02 0:02 ` Rik van Riel
2016-10-01 20:31 ` [PATCH RFC 2/5] x86,fpu: delay FPU register loading until switch to userspace riel
2016-10-01 23:44 ` Andy Lutomirski
2016-10-02 0:08 ` Rik van Riel
2016-10-03 20:54 ` Andy Lutomirski
2016-10-03 21:21 ` Rik van Riel
2016-10-03 21:36 ` Andy Lutomirski
2016-10-04 1:29 ` Rik van Riel
2016-10-04 2:09 ` Andy Lutomirski
2016-10-04 2:47 ` Rik van Riel
2016-10-04 3:02 ` Andy Lutomirski
2016-10-04 6:35 ` Ingo Molnar
2016-10-04 12:48 ` Rik van Riel
2016-10-04 2:11 ` Rik van Riel
2016-10-04 3:02 ` Andy Lutomirski
2016-10-02 0:42 ` Rik van Riel
2016-10-03 16:23 ` Dave Hansen
2016-10-01 20:31 ` [PATCH RFC 3/5] x86,fpu: add kernel fpu argument to __kernel_fpu_begin riel
2016-10-01 20:31 ` [PATCH RFC 4/5] x86,fpu: lazily skip FPU restore when still loaded riel
2016-10-03 20:04 ` Dave Hansen
2016-10-03 20:22 ` Rik van Riel
2016-10-03 20:49 ` Dave Hansen
2016-10-03 21:02 ` Rik van Riel [this message]
2016-10-01 20:31 ` [PATCH RFC 5/5] x86,fpu: kinda sorta fix up signal path riel
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