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From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Satyam Sharma <satyam@infradead.org>,
	Christoph Lameter <clameter@sgi.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Paul Mackerras <paulus@samba.org>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	heiko.carstens@de.ibm.com, horms@verge.net.au,
	linux-kernel@vger.kernel.org, rpjday@mindspring.com, ak@suse.de,
	netdev@vger.kernel.org, cfriesen@nortel.com,
	akpm@linux-foundation.org, jesper.juhl@gmail.com,
	linux-arch@vger.kernel.org, zlynx@acm.org,
	schwidefsky@de.ibm.com, Chris Snook <csnook@redhat.com>,
	davem@davemloft.net, wensong@linux-vs.org, wjiang@resilience.com
Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures
Date: Sat, 18 Aug 2007 15:41:13 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.0.999.0708181526270.30176@woody.linux-foundation.org> (raw)
In-Reply-To: <20070818215409.GC7628@linux.vnet.ibm.com>



On Sat, 18 Aug 2007, Paul E. McKenney wrote:
> 
> One of the gcc guys claimed that he thought that the two-instruction
> sequence would be faster on some x86 machines.  I pointed out that
> there might be a concern about code size.  I chose not to point out
> that people might also care about the other x86 machines.  ;-)

Some (very few) x86 uarchs do tend to prefer "load-store" like code 
generation, and doing a "mov [mem],reg + op reg" instead of "op [mem]" can 
actually be faster on some of them. Not any that are relevant today, 
though.

Also, that has nothing to do with volatile, and should be controlled by 
optimization flags (like -mtune). In fact, I thought there was a separate 
flag to do that (ie something like "-mload-store"), but I can't find it, 
so maybe that's just my fevered brain..

			Linus

  reply	other threads:[~2007-08-18 22:49 UTC|newest]

Thread overview: 333+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-09 13:14 [PATCH 0/24] make atomic_read() behave consistently across all architectures Chris Snook
2007-08-09 12:41 ` Arnd Bergmann
2007-08-09 14:29   ` Chris Snook
2007-08-09 15:30     ` Arnd Bergmann
2007-08-14 22:31 ` Christoph Lameter
2007-08-14 22:45   ` Chris Snook
2007-08-14 22:51     ` Christoph Lameter
2007-08-14 23:08   ` Satyam Sharma
2007-08-14 23:04     ` Chris Snook
2007-08-14 23:14       ` Christoph Lameter
2007-08-15  6:49       ` Herbert Xu
2007-08-15  6:49         ` Herbert Xu
2007-08-15  8:18         ` Heiko Carstens
2007-08-15 13:53           ` Stefan Richter
2007-08-15 14:35             ` Satyam Sharma
2007-08-15 14:52               ` Herbert Xu
2007-08-15 16:09                 ` Stefan Richter
2007-08-15 16:27                   ` Paul E. McKenney
2007-08-15 17:13                     ` Satyam Sharma
2007-08-15 18:31                     ` Segher Boessenkool
2007-08-15 18:57                       ` Paul E. McKenney
2007-08-15 19:54                         ` Satyam Sharma
2007-08-15 20:17                           ` Paul E. McKenney
2007-08-15 20:52                             ` Segher Boessenkool
2007-08-15 22:42                               ` Paul E. McKenney
2007-08-15 20:47                           ` Segher Boessenkool
2007-08-16  0:36                             ` Satyam Sharma
2007-08-16  0:36                               ` (unknown) Satyam Sharma
2007-08-16  0:32                               ` your mail Herbert Xu
2007-08-16  0:58                                 ` [PATCH 0/24] make atomic_read() behave consistently across all architectures Satyam Sharma
2007-08-16  0:51                                   ` Herbert Xu
2007-08-16  1:18                                     ` Satyam Sharma
2007-08-16  1:38                               ` Segher Boessenkool
2007-08-15 21:05                         ` [PATCH 0/24] make atomic_read() behave consistently across all architectures Segher Boessenkool
2007-08-15 22:44                           ` Paul E. McKenney
2007-08-16  1:23                             ` Segher Boessenkool
2007-08-16  2:22                               ` Paul E. McKenney
2007-08-15 19:58               ` Stefan Richter
2007-08-16  0:39           ` [PATCH] i386: Fix a couple busy loops in mach_wakecpu.h:wait_for_init_deassert() Satyam Sharma
2007-08-24 11:59             ` Denys Vlasenko
2007-08-24 12:07               ` Andi Kleen
2007-08-24 12:12               ` Kenn Humborg
2007-08-24 12:12                 ` Kenn Humborg
2007-08-24 14:25                 ` Denys Vlasenko
2007-08-24 17:34                   ` Linus Torvalds
2007-08-24 13:30               ` Satyam Sharma
2007-08-24 17:06                 ` Christoph Lameter
2007-08-24 20:26                   ` Denys Vlasenko
2007-08-24 20:34                     ` Chris Snook
2007-08-24 16:19               ` Luck, Tony
2007-08-24 16:19                 ` Luck, Tony
2007-08-15 16:13         ` [PATCH 0/24] make atomic_read() behave consistently across all architectures Chris Snook
2007-08-15 23:40           ` Herbert Xu
2007-08-15 23:51             ` Paul E. McKenney
2007-08-16  1:30               ` Segher Boessenkool
2007-08-16  2:30                 ` Paul E. McKenney
2007-08-16 19:33                   ` Segher Boessenkool
2007-08-16  1:26             ` Segher Boessenkool
2007-08-16  2:23               ` Nick Piggin
2007-08-16 19:32                 ` Segher Boessenkool
2007-08-17  2:19                   ` Nick Piggin
2007-08-17  3:16                     ` Paul Mackerras
2007-08-17  3:32                       ` Nick Piggin
2007-08-17  3:50                         ` Linus Torvalds
2007-08-17 23:59                           ` Paul E. McKenney
2007-08-18  0:09                             ` Herbert Xu
2007-08-18  1:08                               ` Paul E. McKenney
2007-08-18  1:24                                 ` Christoph Lameter
2007-08-18  1:41                                   ` Satyam Sharma
2007-08-18  4:13                                     ` Linus Torvalds
2007-08-18 13:36                                       ` Satyam Sharma
2007-08-18 21:54                                       ` Paul E. McKenney
2007-08-18 22:41                                         ` Linus Torvalds [this message]
2007-08-18 23:19                                           ` Paul E. McKenney
2007-08-24 12:19                                       ` Denys Vlasenko
2007-08-24 17:19                                         ` Linus Torvalds
2007-08-18 21:56                                   ` Paul E. McKenney
2007-08-20 13:31                                   ` Chris Snook
2007-08-20 22:04                                     ` Segher Boessenkool
2007-08-20 22:48                                       ` Russell King
2007-08-20 23:02                                         ` Segher Boessenkool
2007-08-21  0:05                                           ` Paul E. McKenney
2007-08-21  7:08                                             ` Russell King
2007-08-21  7:05                                           ` Russell King
2007-08-21  9:33                                             ` Paul Mackerras
2007-08-21 11:37                                               ` Andi Kleen
2007-08-21 14:48                                               ` Segher Boessenkool
2007-08-21 16:16                                                 ` Paul E. McKenney
2007-08-21 22:51                                                   ` Valdis.Kletnieks
2007-08-22  0:50                                                     ` Paul E. McKenney
2007-08-22 21:38                                                     ` Adrian Bunk
2007-08-21 14:39                                             ` Segher Boessenkool
2007-08-17  3:42                       ` Linus Torvalds
2007-08-17  5:18                         ` Paul E. McKenney
2007-08-17  5:56                         ` Satyam Sharma
2007-08-17  7:26                           ` Nick Piggin
2007-08-17  8:47                             ` Satyam Sharma
2007-08-17  9:15                               ` Nick Piggin
2007-08-17 10:12                                 ` Satyam Sharma
2007-08-17 12:14                                   ` Nick Piggin
2007-08-17 13:05                                     ` Satyam Sharma
2007-08-17  9:48                               ` Paul Mackerras
2007-08-17 10:23                                 ` Satyam Sharma
2007-08-17 22:49                           ` Segher Boessenkool
2007-08-17 23:51                             ` Satyam Sharma
2007-08-17 23:55                               ` Segher Boessenkool
2007-08-17  6:42                         ` Geert Uytterhoeven
2007-08-17  8:52                         ` Andi Kleen
2007-08-17 10:08                           ` Satyam Sharma
2007-08-17 22:29                         ` Segher Boessenkool
2007-08-17 17:37                     ` Segher Boessenkool
2007-08-14 23:26     ` Paul E. McKenney
2007-08-15 10:35     ` Stefan Richter
2007-08-15 12:04       ` Herbert Xu
2007-08-15 12:31       ` Satyam Sharma
2007-08-15 13:08         ` Stefan Richter
2007-08-15 13:11           ` Stefan Richter
2007-08-15 13:47           ` Satyam Sharma
2007-08-15 14:25             ` Paul E. McKenney
2007-08-15 15:33               ` Herbert Xu
2007-08-15 16:08                 ` Paul E. McKenney
2007-08-15 17:18                   ` Satyam Sharma
2007-08-15 17:33                     ` Paul E. McKenney
2007-08-15 18:05                       ` Satyam Sharma
2007-08-15 17:55               ` Satyam Sharma
2007-08-15 19:07                 ` Paul E. McKenney
2007-08-15 21:07                   ` Segher Boessenkool
2007-08-15 20:58                 ` Segher Boessenkool
2007-08-15 18:19               ` David Howells
2007-08-15 18:45                 ` Paul E. McKenney
2007-08-15 23:41                   ` Herbert Xu
2007-08-15 23:53                     ` Paul E. McKenney
2007-08-16  0:12                       ` Herbert Xu
2007-08-16  0:23                         ` Paul E. McKenney
2007-08-16  0:30                           ` Herbert Xu
2007-08-16  0:49                             ` Paul E. McKenney
2007-08-16  0:53                               ` Herbert Xu
2007-08-16  1:14                                 ` Paul E. McKenney
2007-08-15 18:31         ` Segher Boessenkool
2007-08-15 19:40           ` Satyam Sharma
2007-08-15 20:42             ` Segher Boessenkool
2007-08-16  1:23               ` Satyam Sharma
2007-08-15 23:22         ` Paul Mackerras
2007-08-16  0:26           ` Christoph Lameter
2007-08-16  0:34             ` Paul Mackerras
2007-08-16  0:40               ` Christoph Lameter
2007-08-16  0:39             ` Paul E. McKenney
2007-08-16  0:42               ` Christoph Lameter
2007-08-16  0:53                 ` Paul E. McKenney
2007-08-16  0:59                   ` Christoph Lameter
2007-08-16  1:14                     ` Paul E. McKenney
2007-08-16  1:41                       ` Christoph Lameter
2007-08-16  2:15                         ` Satyam Sharma
2007-08-16  2:08                           ` Herbert Xu
2007-08-16  2:18                             ` Christoph Lameter
2007-08-16  3:23                               ` Paul Mackerras
2007-08-16  3:33                                 ` Herbert Xu
2007-08-16  3:48                                   ` Paul Mackerras
2007-08-16  4:03                                     ` Herbert Xu
2007-08-16  4:34                                       ` Paul Mackerras
2007-08-16  5:37                                         ` Herbert Xu
2007-08-16  6:00                                           ` Paul Mackerras
2007-08-16 18:50                                             ` Christoph Lameter
2007-08-16 18:48                                 ` Christoph Lameter
2007-08-16 19:44                                 ` Segher Boessenkool
2007-08-16  2:18                             ` Chris Friesen
2007-08-16  2:32                         ` Paul E. McKenney
2007-08-16  1:51                 ` Paul Mackerras
2007-08-16  2:00                   ` Herbert Xu
2007-08-16  2:05                     ` Paul Mackerras
2007-08-16  2:11                       ` Herbert Xu
2007-08-16  2:35                         ` Paul E. McKenney
2007-08-16  3:15                         ` Paul Mackerras
2007-08-16  3:43                           ` Herbert Xu
2007-08-16  2:15                       ` Christoph Lameter
2007-08-16  2:17                         ` Christoph Lameter
2007-08-16  2:33                       ` Satyam Sharma
2007-08-16  3:01                         ` Satyam Sharma
2007-08-16  4:11                           ` Paul Mackerras
2007-08-16  5:39                             ` Herbert Xu
2007-08-16  6:56                               ` Paul Mackerras
2007-08-16  7:09                                 ` Herbert Xu
2007-08-16  8:06                                   ` Stefan Richter
2007-08-16  8:10                                     ` Herbert Xu
2007-08-16  9:54                                       ` Stefan Richter
2007-08-16 10:31                                         ` Stefan Richter
2007-08-16 10:42                                           ` Herbert Xu
2007-08-16 16:34                                             ` Paul E. McKenney
2007-08-16 23:59                                               ` Herbert Xu
2007-08-17  1:01                                                 ` Paul E. McKenney
2007-08-17  7:39                                                   ` Satyam Sharma
2007-08-17 14:31                                                     ` Paul E. McKenney
2007-08-17 18:31                                                       ` Satyam Sharma
2007-08-17 18:56                                                         ` Paul E. McKenney
2007-08-17  3:15                                               ` Nick Piggin
2007-08-17  4:02                                                 ` Paul Mackerras
2007-08-17  4:39                                                   ` Nick Piggin
2007-08-17  7:25                                                 ` Stefan Richter
2007-08-17  8:06                                                   ` Nick Piggin
2007-08-17  8:58                                                     ` Satyam Sharma
2007-08-17  9:15                                                       ` Nick Piggin
2007-08-17 10:03                                                         ` Satyam Sharma
2007-08-17 11:50                                                           ` Nick Piggin
2007-08-17 12:50                                                             ` Satyam Sharma
2007-08-17 12:56                                                               ` Nick Piggin
2007-08-17 12:56                                                                 ` Nick Piggin
2007-08-18  2:15                                                                 ` Satyam Sharma
2007-08-17 10:48                                                     ` Stefan Richter
2007-08-17 10:58                                                       ` Stefan Richter
2007-08-18 14:35                                                     ` LDD3 pitfalls (was Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures) Stefan Richter
2007-08-20 13:28                                                       ` Chris Snook
2007-08-17 22:14                                                 ` [PATCH 0/24] make atomic_read() behave consistently across all architectures Segher Boessenkool
2007-08-17  5:04                                             ` Paul Mackerras
2007-08-16 10:35                                         ` Herbert Xu
2007-08-16 19:48                                       ` Chris Snook
2007-08-17  0:02                                         ` Herbert Xu
2007-08-17  2:04                                           ` Chris Snook
2007-08-17  2:13                                             ` Herbert Xu
2007-08-17  2:31                                             ` Nick Piggin
2007-08-17  5:09                                       ` Paul Mackerras
2007-08-17  5:32                                         ` Herbert Xu
2007-08-17  5:41                                           ` Paul Mackerras
2007-08-17  8:28                                             ` Satyam Sharma
2007-08-16 14:48                                   ` Ilpo Järvinen
2007-08-16 16:19                                     ` Stefan Richter
2007-08-16 19:55                                     ` Chris Snook
2007-08-16 20:20                                       ` Christoph Lameter
2007-08-17  1:02                                         ` Paul E. McKenney
2007-08-17  1:28                                           ` Herbert Xu
2007-08-17  5:07                                             ` Paul E. McKenney
2007-08-17  2:16                                         ` Paul Mackerras
2007-08-17  3:03                                           ` Linus Torvalds
2007-08-17  3:43                                             ` Paul Mackerras
2007-08-17  3:53                                               ` Herbert Xu
2007-08-17  6:26                                                 ` Satyam Sharma
2007-08-17  8:38                                                   ` Nick Piggin
2007-08-17  9:14                                                     ` Satyam Sharma
2007-08-17  9:31                                                       ` Nick Piggin
2007-08-17 10:55                                                         ` Satyam Sharma
2007-08-17 12:39                                                           ` Nick Piggin
2007-08-17 12:39                                                             ` Nick Piggin
2007-08-17 13:36                                                             ` Satyam Sharma
2007-08-17 16:48                                                             ` Linus Torvalds
2007-08-17 18:50                                                               ` Chris Friesen
2007-08-17 18:50                                                                 ` Chris Friesen
2007-08-17 18:54                                                                 ` Arjan van de Ven
2007-08-17 19:49                                                                   ` Paul E. McKenney
2007-08-17 19:49                                                                     ` Arjan van de Ven
2007-08-17 20:12                                                                       ` Paul E. McKenney
2007-08-17 19:08                                                                 ` Linus Torvalds
2007-08-20 13:15                                                               ` Chris Snook
2007-08-20 13:15                                                                 ` Chris Snook
2007-08-20 13:32                                                                 ` Herbert Xu
2007-08-20 13:38                                                                   ` Chris Snook
2007-08-20 22:07                                                                     ` Segher Boessenkool
2007-08-21  5:46                                                                 ` Linus Torvalds
2007-08-21  7:04                                                                   ` David Miller
2007-08-21 13:50                                                                     ` Chris Snook
2007-08-21 14:59                                                                       ` Segher Boessenkool
2007-08-21 16:31                                                                       ` Satyam Sharma
2007-08-21 16:43                                                                       ` Linus Torvalds
2007-09-09 18:02                                                               ` Denys Vlasenko
2007-09-09 18:18                                                                 ` Arjan van de Ven
2007-09-10 10:56                                                                   ` Denys Vlasenko
2007-09-10 11:15                                                                     ` Herbert Xu
2007-09-10 12:22                                                                     ` Kyle Moffett
2007-09-10 12:22                                                                       ` Kyle Moffett
2007-09-10 13:38                                                                       ` Denys Vlasenko
2007-09-10 13:38                                                                         ` Denys Vlasenko
2007-09-10 14:16                                                                         ` Denys Vlasenko
2007-09-10 14:16                                                                           ` Denys Vlasenko
2007-09-10 15:09                                                                           ` Linus Torvalds
2007-09-10 16:46                                                                             ` Denys Vlasenko
2007-09-10 19:59                                                                               ` Kyle Moffett
2007-09-10 19:59                                                                                 ` Kyle Moffett
2007-09-10 18:59                                                                             ` Christoph Lameter
2007-09-10 23:19                                                                             ` [PATCH] Document non-semantics of atomic_read() and atomic_set() Chris Snook
2007-09-10 23:19                                                                               ` Chris Snook
2007-09-10 23:44                                                                               ` Paul E. McKenney
2007-09-10 23:44                                                                                 ` Paul E. McKenney
2007-09-11 19:35                                                                               ` Christoph Lameter
2007-09-11 19:35                                                                                 ` Christoph Lameter
2007-09-10 14:51                                                                     ` [PATCH 0/24] make atomic_read() behave consistently across all architectures Arjan van de Ven
2007-09-10 14:38                                                                       ` Denys Vlasenko
2007-09-10 17:02                                                                         ` Arjan van de Ven
2007-08-17 11:08                                                     ` Stefan Richter
2007-08-17 22:09                                             ` Segher Boessenkool
2007-08-17 22:09                                               ` Segher Boessenkool
2007-08-17 17:41                                         ` Segher Boessenkool
2007-08-17 18:38                                           ` Satyam Sharma
2007-08-17 23:17                                             ` Segher Boessenkool
2007-08-17 23:17                                               ` Segher Boessenkool
2007-08-17 23:55                                               ` Satyam Sharma
2007-08-18  0:04                                                 ` Segher Boessenkool
2007-08-18  0:04                                                   ` Segher Boessenkool
2007-08-18  1:56                                                   ` Satyam Sharma
2007-08-18  2:15                                                     ` Segher Boessenkool
2007-08-18  2:15                                                       ` Segher Boessenkool
2007-08-18  3:33                                                       ` Satyam Sharma
2007-08-18  5:18                                                         ` Segher Boessenkool
2007-08-18  5:18                                                           ` Segher Boessenkool
2007-08-18 13:20                                                           ` Satyam Sharma
2007-09-10 18:59                                           ` Christoph Lameter
2007-09-10 20:54                                             ` Paul E. McKenney
2007-09-10 21:36                                               ` Christoph Lameter
2007-09-10 21:50                                                 ` Paul E. McKenney
2007-09-11  2:27                                             ` Segher Boessenkool
2007-09-11  2:27                                               ` Segher Boessenkool
2007-08-16 21:08                                       ` Luck, Tony
2007-08-16 21:08                                         ` Luck, Tony
2007-08-16 19:55                                     ` Chris Snook
2007-08-16 18:54                             ` Christoph Lameter
2007-08-16 20:07                               ` Paul E. McKenney
2007-08-16  3:05                         ` Paul Mackerras
2007-08-16 19:39                           ` Segher Boessenkool
2007-08-16  2:07                   ` Segher Boessenkool
2007-08-24 12:50           ` Denys Vlasenko
2007-08-24 17:15             ` Christoph Lameter
2007-08-24 20:21               ` Denys Vlasenko
2007-08-16  3:37         ` Bill Fink
2007-08-16  5:20           ` Satyam Sharma
2007-08-16  5:57             ` Satyam Sharma
2007-08-16  9:25               ` Satyam Sharma
2007-08-16 21:00               ` Segher Boessenkool
2007-08-17  4:32                 ` Satyam Sharma
2007-08-17 22:38                   ` Segher Boessenkool
2007-08-18 14:42                     ` Satyam Sharma
2007-08-16 20:50             ` Segher Boessenkool
2007-08-16 22:40               ` David Schwartz
2007-08-17  4:36                 ` Satyam Sharma
2007-08-17  4:24               ` Satyam Sharma
2007-08-17 22:34                 ` Segher Boessenkool
2007-08-15 19:59       ` Christoph Lameter

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