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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: David Miller <davem@davemloft.net>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	linuxppc-dev@ozlabs.org, scottwood@freescale.com,
	torvalds@linux-foundation.org, tpiepho@freescale.com
Subject: Re: MMIO and gcc re-ordering issue
Date: Tue, 27 May 2008 09:24:30 +0100	[thread overview]
Message-ID: <20080527092430.6380d962@core> (raw)
In-Reply-To: <20080526.192812.184590464.davem@davemloft.net>

> It's just another complicated thing for driver authors to get wrong.
> The other side of the coin is of course the cost.
> 
> The only thing I am absolutely sure of is that we should make a
> decision fast, document it, and just stick to it.

It's unfortunate that the __read/___write versions have other different
semantics. The default should definitely be ordered but having un-ordered
ones as an option would be good for zapping the hot paths that matter.

Most I/O paths aren't even worth the thinking time for non-ordered I/O.

Alan

  parent reply	other threads:[~2008-05-27  8:41 UTC|newest]

Thread overview: 160+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-20 20:40 [PATCH] [POWERPC] Improve (in|out)_beXX() asm code Trent Piepho
2008-05-20 21:16 ` Benjamin Herrenschmidt
2008-05-20 21:38   ` Scott Wood
2008-05-20 22:02     ` Benjamin Herrenschmidt
2008-05-20 22:21       ` Trent Piepho
2008-05-20 22:15     ` Alan Cox
2008-05-20 22:35       ` Scott Wood
2008-05-20 22:39         ` David Miller
2008-05-20 22:43           ` Scott Wood
2008-05-20 22:53             ` David Miller
2008-05-23  4:24               ` Benjamin Herrenschmidt
2008-05-22 22:56                 ` Trent Piepho
2008-05-23 12:36                   ` MMIO and gcc re-ordering (Was: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code) Benjamin Herrenschmidt
2008-05-23 12:50                     ` Benjamin Herrenschmidt
2008-05-23 21:14                       ` Scott Wood
2008-05-23 22:47                         ` Benjamin Herrenschmidt
2008-05-27  1:33                   ` MMIO and gcc re-ordering issue Benjamin Herrenschmidt
2008-05-27  1:40                     ` David Miller
2008-05-27  2:15                       ` Benjamin Herrenschmidt
2008-05-27  2:28                         ` David Miller
2008-05-27  3:39                           ` Benjamin Herrenschmidt
2008-05-27 15:35                             ` Linus Torvalds
2008-05-27 16:47                               ` Linus Torvalds
2008-05-27 17:31                                 ` Linus Torvalds
2008-06-02 10:36                                   ` Ingo Molnar
2008-06-02 21:53                                     ` Benjamin Herrenschmidt
2008-05-27 21:12                                 ` Benjamin Herrenschmidt
2008-05-27 18:23                               ` Trent Piepho
2008-05-27 18:33                                 ` Scott Wood
2008-05-27 21:10                               ` Benjamin Herrenschmidt
2008-05-27 21:30                                 ` Linus Torvalds
2008-05-27 21:38                                   ` Alan Cox
2008-05-27 21:53                                     ` Matthew Wilcox
2008-05-27 21:46                                       ` Alan Cox
2008-05-27 22:02                                       ` Linus Torvalds
2008-05-27 21:59                                     ` Linus Torvalds
2008-05-27 21:38                                   ` Benjamin Herrenschmidt
2008-05-27 21:42                                     ` Matthew Wilcox
2008-05-27 22:17                                       ` Benjamin Herrenschmidt
2008-05-28  8:36                                         ` Haavard Skinnemoen
2008-05-29 11:05                                           ` Pantelis Antoniou
2008-05-30  1:13                                           ` Benjamin Herrenschmidt
2008-05-30  6:07                                             ` Haavard Skinnemoen
2008-05-30  7:24                                               ` Benjamin Herrenschmidt
2008-05-30  8:27                                                 ` Haavard Skinnemoen
2008-05-30  9:22                                                   ` Geert Uytterhoeven
2008-06-02  8:11                                                     ` Haavard Skinnemoen
2008-06-02 15:48                                                       ` Scott Wood
2008-06-03  7:46                                                         ` Haavard Skinnemoen
2008-06-04 15:31                                                       ` Linus Torvalds
2008-05-27 21:55                                     ` Linus Torvalds
2008-05-27 22:19                                       ` Benjamin Herrenschmidt
2008-05-29  7:10                                         ` Arnd Bergmann
2008-05-29 10:46                                           ` Alan Cox
2008-06-02  7:24                                       ` Russell King
2008-06-03  4:16                                         ` Nick Piggin
2008-06-03  4:32                                           ` Benjamin Herrenschmidt
2008-06-03  6:11                                             ` Nick Piggin
2008-06-03  6:48                                               ` Benjamin Herrenschmidt
2008-06-03  6:53                                               ` Paul Mackerras
2008-06-03  7:18                                                 ` Nick Piggin
2008-06-03 14:47                                           ` Linus Torvalds
2008-06-03 18:47                                             ` Trent Piepho
2008-06-03 18:55                                               ` Matthew Wilcox
2008-06-03 19:57                                                 ` Trent Piepho
2008-06-03 21:35                                                   ` Matthew Wilcox
2008-06-03 21:58                                                     ` Trent Piepho
2008-06-04  2:00                                                       ` Nick Piggin
2008-06-03 19:07                                               ` Linus Torvalds
2008-06-04  2:05                                                 ` Nick Piggin
2008-06-04  2:46                                                   ` Linus Torvalds
2008-06-04 11:47                                                     ` Alan Cox
2008-06-10  6:56                                                 ` Nick Piggin
2008-06-10 17:41                                                   ` Jesse Barnes
2008-06-10 18:10                                                     ` James Bottomley
2008-06-10 19:05                                                       ` Roland Dreier
2008-06-10 19:19                                                         ` Jesse Barnes
2008-06-11  3:29                                                           ` Nick Piggin
2008-06-11  3:40                                                             ` Benjamin Herrenschmidt
2008-06-11  4:06                                                               ` Nick Piggin
2008-06-11 16:07                                                             ` Jesse Barnes
2008-06-12 11:27                                                               ` Nick Piggin
2008-06-11  4:18                                                   ` Paul Mackerras
2008-06-11  5:00                                                     ` Nick Piggin
2008-06-11  5:13                                                       ` Paul Mackerras
2008-06-11  5:35                                                         ` Nick Piggin
2008-06-11  6:02                                                           ` Nick Piggin
2008-06-12 12:14                                                           ` Paul Mackerras
2008-06-12 13:08                                                             ` Nick Piggin
2008-06-11 14:46                                                       ` Linus Torvalds
2008-06-11  5:20                                                   ` Paul Mackerras
2008-06-04  2:19                                             ` Nick Piggin
2008-06-03 19:43                                           ` Trent Piepho
2008-06-03 21:33                                             ` Matthew Wilcox
2008-06-03 21:44                                               ` Trent Piepho
2008-06-04  2:25                                                 ` Nick Piggin
2008-06-04  6:39                                                   ` Trent Piepho
2008-06-03 22:26                                             ` Benjamin Herrenschmidt
2008-05-27  3:42                           ` Arjan van de Ven
2008-05-27  4:08                             ` Roland Dreier
2008-05-27  4:20                               ` Arjan van de Ven
2008-05-27  7:08                             ` Benjamin Herrenschmidt
2008-05-27 15:50                               ` Roland Dreier
2008-05-27 16:37                                 ` James Bottomley
2008-05-27 17:38                                   ` Roland Dreier
2008-05-27 17:53                                     ` James Bottomley
2008-05-27 18:07                                       ` Roland Dreier
2008-05-27 18:17                                         ` Roland Dreier
2008-05-27 21:23                                         ` Chris Friesen
2008-05-27 21:29                                           ` Roland Dreier
2008-05-27 23:04                                           ` Paul Mackerras
2008-05-27 21:11                                 ` Benjamin Herrenschmidt
2008-05-27 21:33                                   ` Roland Dreier
2008-05-27 22:13                                     ` Benjamin Herrenschmidt
2008-05-27 22:39                                       ` Roland Dreier
2008-05-29 14:47                                     ` Jes Sorensen
2008-05-29 15:01                                       ` James Bottomley
2008-05-30  9:36                                         ` Jes Sorensen
2008-05-30 17:21                                           ` Jesse Barnes
2008-05-31  7:57                                             ` Jeremy Higdon
2008-05-29 21:40                                       ` Benjamin Herrenschmidt
2008-05-29 21:48                                         ` Trent Piepho
2008-05-29 22:05                                           ` Benjamin Herrenschmidt
2008-05-30  1:53                                             ` Trent Piepho
2008-05-29 21:53                                         ` Jesse Barnes
2008-05-30  9:39                                           ` Jes Sorensen
2008-05-30  9:48                                         ` Jes Sorensen
2008-05-31  8:14                                           ` Pavel Machek
2008-06-02  9:48                                             ` Jes Sorensen
2008-05-29 22:06                                       ` Roland Dreier
2008-05-29 22:25                                         ` Trent Piepho
2008-05-30  3:56                                           ` Paul Mackerras
2008-05-31  7:52                                       ` Jeremy Higdon
2008-06-02  9:56                                         ` Jes Sorensen
2008-06-02 21:02                                           ` Jeremy Higdon
2008-06-03  4:33                                           ` Nick Piggin
2008-06-03  8:15                                             ` Jeremy Higdon
2008-06-03  8:19                                               ` Nick Piggin
2008-06-03  8:45                                                 ` Jeremy Higdon
2008-06-03 16:52                                             ` Jesse Barnes
2008-06-05  8:40                                               ` Jes Sorensen
2008-06-05  8:43                                                 ` Benjamin Herrenschmidt
2008-06-12 15:07                                                   ` Matthew Wilcox
2008-06-13  0:07                                                     ` Benjamin Herrenschmidt
2008-05-31  8:04                                 ` Pavel Machek
2008-05-27  8:24                           ` Alan Cox [this message]
2008-05-27 15:28                     ` Jonathan Corbet
2008-05-20 22:55         ` [PATCH] [POWERPC] Improve (in|out)_beXX() asm code Trent Piepho
2008-05-21 14:01           ` Benjamin Herrenschmidt
2008-05-20 22:00   ` Trent Piepho
2008-05-21 14:00     ` Benjamin Herrenschmidt
2008-05-21 19:44       ` Trent Piepho
2008-05-21 20:41         ` Benjamin Herrenschmidt
2008-05-20 22:00 ` Andreas Schwab
2008-05-20 22:11   ` Trent Piepho
2008-05-20 22:47     ` Andreas Schwab
2008-05-20 23:14       ` Trent Piepho
2008-05-21  8:03         ` Andreas Schwab
2008-05-21 20:25           ` Trent Piepho
2008-05-27 23:48           ` [PATCH V2] [POWERPC] Improve (in|out)_[bl]eXX() " Trent Piepho

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