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From: "H. Peter Anvin" <hpa@zytor.com>
To: Luca Barbieri <luca@luca-barbieri.com>
Cc: Andi Kleen <andi@firstfloor.org>,
	mingo@elte.hu, a.p.zijlstra@chello.nl, akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/10] x86-32: use SSE for atomic64_read/set if available
Date: Thu, 18 Feb 2010 11:07:12 -0800	[thread overview]
Message-ID: <4B7D8FE0.1040602@zytor.com> (raw)
In-Reply-To: <ff13bc9a1002181042p7414c18fu77208b6bc7aa41df@mail.gmail.com>

On 02/18/2010 10:42 AM, Luca Barbieri wrote:
>> We already do that kind of stuff, using
>> kernel_fpu_begin()..kernel_fpu_end().  We went through some pain a bit
>> ago to clean up "private hacks" that complicated things substantially.
> 
> But that saves the whole FPU state on the first usage, and also
> triggers a fault when userspace attempts to use it again.
> Additionally it does a clts/stts every time which is slow for small
> algorithms (lke the atomic64 routines).
> 
> The first issue can be solved by using SSE and saving only the used
> registers, and the second with lazy TS flag restoring.
> 

Again, I want to see a strong use case before even *considering* making
the rules we already have any more complex.

	-hpa

  reply	other threads:[~2010-02-18 19:08 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-17 11:42 [PATCH 0/10] x86-32: improve atomic64_t functions Luca Barbieri
2010-02-17 11:42 ` [PATCH 01/10] x86: add support for multiple choice alternatives Luca Barbieri
2010-02-17 12:47   ` Avi Kivity
2010-02-18 19:46     ` H. Peter Anvin
2010-02-17 11:42 ` [PATCH 02/10] x86: add support for relative CALL and JMP in alternatives Luca Barbieri
2010-02-18 19:40   ` H. Peter Anvin
2010-02-18 23:38     ` Luca Barbieri
2010-02-18 23:54       ` H. Peter Anvin
2010-02-19 14:27   ` Masami Hiramatsu
2010-02-17 11:42 ` [PATCH 03/10] x86: add support for lock prefix " Luca Barbieri
2010-02-17 11:42 ` [PATCH 04/10] x86-32: allow UP/SMP lock replacement in cmpxchg64 Luca Barbieri
2010-02-17 11:42 ` [PATCH 05/10] lib: add self-test for atomic64_t Luca Barbieri
2010-02-17 11:42 ` [PATCH 06/10] x86-32: rewrite 32-bit atomic64 functions in assembly Luca Barbieri
2010-02-17 11:42 ` [PATCH 07/10] lib: move generic atomic64 to atomic64-impl.h Luca Barbieri
2010-02-17 11:42 ` [PATCH 08/10] x86-32: support atomic64_t on 386/486 UP/SMP Luca Barbieri
2010-02-18 10:25   ` Peter Zijlstra
2010-02-18 10:58     ` Luca Barbieri
2010-02-18 15:20     ` H. Peter Anvin
2010-02-17 11:42 ` [PATCH 09/10] x86-32: use SSE for atomic64_read/set if available Luca Barbieri
2010-02-17 22:39   ` H. Peter Anvin
2010-02-18  0:41     ` Luca Barbieri
2010-02-18  0:47       ` H. Peter Anvin
2010-02-18  9:56         ` Avi Kivity
2010-02-18 10:07           ` Luca Barbieri
2010-02-18  8:23   ` Andi Kleen
2010-02-18  9:53     ` Luca Barbieri
2010-02-18  9:56       ` Luca Barbieri
2010-02-18 10:11       ` Andi Kleen
2010-02-18 10:27         ` Luca Barbieri
2010-02-18 15:24           ` H. Peter Anvin
2010-02-18 18:14             ` Luca Barbieri
2010-02-18 18:28               ` H. Peter Anvin
2010-02-18 18:42                 ` Luca Barbieri
2010-02-18 19:07                   ` H. Peter Anvin [this message]
2010-02-18 20:26               ` Andi Kleen
2010-02-18 16:52           ` H. Peter Anvin
2010-02-18 18:49             ` Luca Barbieri
2010-02-18 19:06               ` H. Peter Anvin
2010-02-18 19:43                 ` Luca Barbieri
2010-02-18 19:45                 ` Yuhong Bao
2010-02-18 10:24       ` Peter Zijlstra
2010-02-18 10:25   ` Peter Zijlstra
2010-02-18 10:50     ` Luca Barbieri
2010-02-18 11:00       ` Peter Zijlstra
2010-02-18 12:29         ` Luca Barbieri
2010-02-18 12:32           ` Peter Zijlstra
2010-02-18 13:45             ` Luca Barbieri
2010-02-17 11:42 ` [PATCH 10/10] x86-32: panic on !CX8 && XMM Luca Barbieri
2010-02-17 22:38   ` H. Peter Anvin
2010-02-17 23:00     ` Yuhong Bao
2010-02-17 23:41       ` H. Peter Anvin
2010-02-18  1:13         ` Yuhong Bao
2010-02-25 20:24           ` Yuhong Bao
2010-02-18  0:46     ` Luca Barbieri

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