From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Boyer <jwboyer@gmail.com>,
Jongman Heo <jongman.heo@samsung.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] i387: support lazy restore of FPU state
Date: Mon, 20 Feb 2012 18:32:16 -0800 [thread overview]
Message-ID: <4F430230.1010505@zytor.com> (raw)
In-Reply-To: <CA+55aFzottbJCxhh+qJnhk=yZ3Rjf=0ndn7vVvvcjWrBSthEYg@mail.gmail.com>
On 02/20/2012 06:18 PM, Linus Torvalds wrote:
>
>> Although I do wonder if we should just make kernel_fpu_begin() be a
>> real function instead of inlining it. I'm not sure it makes sense to
>> inline that thing, and it might be better to export that one instead.
>
> I do think that would be better in the long run, but for now here's an
> updated "trivial" patch to fix it.
>
There is actually another very good reason for out-of-lining
kernel_fpu_begin/_end: it will act as a compiler barrier i we ever do
compiler-generated SSE or AVX code, which we may very well want to do.
In fact, there may even be good reason for something like:
kernel_fpu_use(void (*func)(void *), void *arg);
... where the FPU-using stuff is actively embedded in the call.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-02-21 2:32 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-19 22:23 [PATCH 0/2] More i387 state save/restore work Linus Torvalds
2012-02-19 22:26 ` [PATCH 1/2] i387: use 'restore_fpu_checking()' directly in task switching code Linus Torvalds
2012-02-19 22:37 ` [PATCH 2/2] i387: support lazy restore of FPU state Linus Torvalds
2012-02-19 22:44 ` H. Peter Anvin
2012-02-19 23:18 ` H. Peter Anvin
2012-02-19 23:56 ` Linus Torvalds
2012-02-20 7:51 ` Ingo Molnar
2012-02-20 0:53 ` [PATCH 0/2] More i387 state save/restore work Michael Neuling
2012-02-20 1:03 ` Linus Torvalds
2012-02-20 1:06 ` Linus Torvalds
2012-02-20 1:11 ` Linus Torvalds
2012-03-01 11:30 ` Benjamin Herrenschmidt
2012-02-20 2:09 ` Indan Zupancic
2012-02-20 19:46 ` [PATCH v2 0/3] " Linus Torvalds
2012-02-20 19:47 ` [PATCH v2 1/3] i387: fix up some fpu_counter confusion Linus Torvalds
2012-02-20 19:48 ` [PATCH v2 2/3] i387: use 'restore_fpu_checking()' directly in task switching code Linus Torvalds
2012-02-20 19:48 ` [PATCH v2 3/3] i387: support lazy restore of FPU state Linus Torvalds
2012-02-21 1:50 ` Josh Boyer
2012-02-21 2:10 ` Linus Torvalds
2012-02-21 2:14 ` H. Peter Anvin
2012-02-21 5:27 ` Linus Torvalds
2012-02-21 5:35 ` H. Peter Anvin
2012-02-21 14:19 ` Josh Boyer
2012-02-21 17:59 ` H. Peter Anvin
2012-02-21 18:06 ` Ingo Molnar
2012-02-21 18:26 ` Linus Torvalds
2012-02-21 21:14 ` H. Peter Anvin
2012-02-21 21:39 ` [PATCH 0/2] i387: FP state interface cleanups Linus Torvalds
2012-02-21 21:40 ` [PATCH 1/2] i387: uninline the generic FP helpers that we expose to kernel modules Linus Torvalds
2012-02-21 21:41 ` [PATCH 2/2] i387: split up <asm/i387.h> into exported and internal interfaces Linus Torvalds
2012-02-21 23:50 ` [tip:x86/fpu] i387: Split " tip-bot for Linus Torvalds
2012-02-28 11:21 ` [PATCH 2/2] i387: split " Avi Kivity
2012-02-28 16:05 ` Linus Torvalds
2012-02-28 17:21 ` Avi Kivity
2012-02-28 17:37 ` Linus Torvalds
2012-02-28 18:08 ` Linus Torvalds
2012-02-28 18:29 ` Avi Kivity
2012-02-28 18:09 ` Avi Kivity
2012-02-28 18:34 ` Linus Torvalds
2012-02-28 19:06 ` Avi Kivity
2012-02-28 19:26 ` Linus Torvalds
2012-02-28 19:45 ` Avi Kivity
2012-02-21 23:49 ` [tip:x86/fpu] i387: Uninline the generic FP helpers that we expose to kernel modules tip-bot for Linus Torvalds
2012-02-21 2:18 ` [PATCH v2 3/3] i387: support lazy restore of FPU state Linus Torvalds
2012-02-21 2:32 ` H. Peter Anvin [this message]
2012-02-21 2:11 ` H. Peter Anvin
2012-02-21 21:54 ` Suresh Siddha
2012-02-21 21:57 ` Linus Torvalds
2012-02-21 22:19 ` Suresh Siddha
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