From: Andi Kleen <ak@suse.de>
To: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 6/8] i386: bitops: Don't mark memory as clobbered unnecessarily
Date: Mon, 23 Jul 2007 18:13:26 +0200 [thread overview]
Message-ID: <200707231813.26859.ak@suse.de> (raw)
In-Reply-To: <20070723160558.22137.71943.sendpatchset@cselinux1.cse.iitk.ac.in>
On Monday 23 July 2007 18:05:58 Satyam Sharma wrote:
> From: Satyam Sharma <ssatyam@cse.iitk.ac.in>
>
> [6/8] i386: bitops: Don't mark memory as clobbered unnecessarily
>
> The goal is to let gcc generate good, beautiful, optimized code.
The first goal is correct code.
The reason for the memory barrier is to prevent other memory references
from being moved over the atomic reference.
e.g. when a bit is used to communicate with another CPU this might be dangerous.
I don't think it's a good idea to remove them. It'll likely introduce subtle
bugs. Atomic bitops tend to be so slow anyways that it doesn't make much
difference.
-Andi
next prev parent reply other threads:[~2007-07-23 16:18 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-23 16:05 [PATCH 0/8] i386: bitops: Cleanup, sanitize, optimize Satyam Sharma
2007-07-23 16:05 ` [PATCH 1/8] i386: bitops: Update/correct comments Satyam Sharma
2007-07-23 16:05 ` [PATCH 2/8] i386: bitops: Rectify bogus "Ir" constraints Satyam Sharma
2007-07-23 16:10 ` Andi Kleen
2007-07-23 16:21 ` Satyam Sharma
2007-07-23 16:30 ` Andi Kleen
2007-07-23 16:36 ` Jan Hubicka
2007-07-23 18:05 ` H. Peter Anvin
2007-07-23 18:28 ` H. Peter Anvin
2007-07-23 17:57 ` Linus Torvalds
2007-07-23 18:14 ` Satyam Sharma
2007-07-23 18:32 ` Andi Kleen
2007-07-23 18:39 ` H. Peter Anvin
2007-07-23 18:52 ` Satyam Sharma
2007-07-23 16:05 ` [PATCH 3/8] i386: bitops: Rectify bogus "+m" constraints Satyam Sharma
2007-07-23 16:37 ` Andi Kleen
2007-07-23 17:15 ` Satyam Sharma
2007-07-23 17:46 ` Linus Torvalds
2007-07-24 9:22 ` David Howells
2007-07-23 16:05 ` [PATCH 4/8] i386: bitops: Kill volatile-casting of memory addresses Satyam Sharma
2007-07-23 17:52 ` Linus Torvalds
2007-07-24 4:19 ` Nick Piggin
2007-07-24 6:23 ` Satyam Sharma
2007-07-24 7:16 ` Nick Piggin
2007-07-24 9:49 ` Benjamin Herrenschmidt
2007-07-24 17:20 ` Linus Torvalds
2007-07-24 17:39 ` Jeff Garzik
2007-07-25 4:54 ` Nick Piggin
2007-07-23 16:05 ` [PATCH 5/8] i386: bitops: Contain warnings fallout from the death of volatiles Satyam Sharma
2007-07-23 16:05 ` [PATCH 6/8] i386: bitops: Don't mark memory as clobbered unnecessarily Satyam Sharma
2007-07-23 16:13 ` Andi Kleen [this message]
2007-07-23 16:26 ` Satyam Sharma
2007-07-23 16:33 ` Andi Kleen
2007-07-23 17:12 ` Satyam Sharma
2007-07-23 17:49 ` Jeremy Fitzhardinge
2007-07-23 17:55 ` Linus Torvalds
2007-07-24 9:52 ` Benjamin Herrenschmidt
2007-07-24 17:24 ` Linus Torvalds
2007-07-24 17:42 ` Trond Myklebust
2007-07-24 18:13 ` Linus Torvalds
2007-07-24 18:28 ` Trond Myklebust
2007-07-24 21:37 ` Benjamin Herrenschmidt
2007-07-24 21:55 ` Trond Myklebust
2007-07-24 22:32 ` Benjamin Herrenschmidt
2007-07-25 4:10 ` Nick Piggin
2007-07-24 21:36 ` Benjamin Herrenschmidt
2007-07-24 3:57 ` Nick Piggin
2007-07-24 6:38 ` Satyam Sharma
2007-07-24 7:24 ` Nick Piggin
2007-07-24 8:29 ` Satyam Sharma
2007-07-24 8:39 ` Nick Piggin
2007-07-24 8:38 ` Trent Piepho
2007-07-24 19:39 ` Linus Torvalds
2007-07-24 20:37 ` Andi Kleen
2007-07-24 20:08 ` Linus Torvalds
2007-07-24 21:31 ` Jeremy Fitzhardinge
2007-07-24 21:46 ` Linus Torvalds
2007-07-26 1:07 ` Trent Piepho
2007-07-26 1:18 ` Linus Torvalds
2007-07-26 1:22 ` Linus Torvalds
2007-07-24 9:44 ` David Howells
2007-07-24 10:02 ` Satyam Sharma
2007-07-23 16:06 ` [PATCH 7/8] i386: bitops: Kill needless usage of __asm__ __volatile__ Satyam Sharma
2007-07-23 16:18 ` Andi Kleen
2007-07-23 16:22 ` [PATCH 7/8] i386: bitops: Kill needless usage of __asm__ __volatile__ II Andi Kleen
2007-07-23 16:32 ` [PATCH 7/8] i386: bitops: Kill needless usage of __asm__ __volatile__ Satyam Sharma
2007-07-23 16:23 ` Jeremy Fitzhardinge
2007-07-23 16:43 ` Satyam Sharma
2007-07-23 17:39 ` Jeremy Fitzhardinge
2007-07-23 18:07 ` Satyam Sharma
2007-07-23 18:28 ` Jeremy Fitzhardinge
2007-07-23 20:29 ` Trent Piepho
2007-07-23 20:40 ` Jeremy Fitzhardinge
2007-07-23 21:06 ` Trent Piepho
2007-07-23 21:30 ` Andi Kleen
2007-07-23 21:48 ` Nicholas Miell
2007-07-23 16:06 ` [PATCH 8/8] i386: bitops: smp_mb__{before, after}_clear_bit() definitions Satyam Sharma
2007-07-24 3:53 ` Nick Piggin
2007-07-24 7:34 ` Satyam Sharma
2007-07-24 7:48 ` Jeremy Fitzhardinge
2007-07-24 8:31 ` Nick Piggin
2007-07-24 8:20 ` Nick Piggin
2007-07-24 9:21 ` Satyam Sharma
2007-07-24 10:25 ` Nick Piggin
2007-07-24 11:10 ` Satyam Sharma
2007-07-24 11:32 ` Nick Piggin
2007-07-24 11:45 ` Satyam Sharma
2007-07-24 12:01 ` Nick Piggin
2007-07-24 17:12 ` Linus Torvalds
2007-07-24 19:01 ` Satyam Sharma
2007-07-30 17:57 ` [PATCH 0/8] i386: bitops: Cleanup, sanitize, optimize Denis Vlasenko
2007-07-31 1:07 ` Satyam Sharma
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