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From: Alan <alan@lxorguk.ukuu.org.uk>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Viktor <vvp01@inbox.ru>, Aubrey <aubreylee@gmail.com>,
	Hua Zhong <hzhong@gmail.com>, Hugh Dickins <hugh@veritas.com>,
	linux-kernel@vger.kernel.org, hch@infradead.org,
	kenneth.w.chen@intel.com, akpm@osdl.org, mjt@tls.msk.ru
Subject: Re: O_DIRECT question
Date: Thu, 11 Jan 2007 17:42:14 +0000	[thread overview]
Message-ID: <20070111174214.676d15b9@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.64.0701110750520.3594@woody.osdl.org>

> space, just as an example) is wrong in the first place, but the really 
> subtle problems come when you realize that you can't really just "bypass" 
> the OS.

Well you can - its called SG_IO and that really does get the OS out of
the way. O_DIRECT gets crazy when you stop using it on devices directly
and use it on files

You do need some way to avoid the copy cost of caches and get data direct
to user space, it also needs to be a way that works without MMU tricks
because many of that need it are the embedded platforms.

Alan

  parent reply	other threads:[~2007-01-11 17:33 UTC|newest]

Thread overview: 130+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-11  2:57 O_DIRECT question Aubrey
2007-01-11  3:05 ` Linus Torvalds
2007-01-11  3:15   ` Linus Torvalds
2007-01-11  6:09     ` Nick Piggin
2007-01-11 15:50       ` Linus Torvalds
2007-01-11 16:19         ` Aubrey
2007-01-16  3:41           ` Jörn Engel
2007-01-11 16:23         ` bert hubert
2007-01-11 16:52         ` Xavier Bestel
2007-01-11 17:04           ` Linus Torvalds
2007-01-11 18:41             ` Trond Myklebust
2007-01-11 19:00               ` Linus Torvalds
2007-01-11 19:49                 ` Trond Myklebust
2007-01-12 17:03             ` Viktor
2007-01-20 16:19         ` Denis Vlasenko
2007-01-22 15:52           ` Phillip Susi
2007-01-11  5:50   ` Aubrey
2007-01-11  6:06     ` Andrew Morton
2007-01-11  6:45       ` Aubrey
2007-01-11  6:57         ` Andrew Morton
2007-01-11  7:05           ` Nick Piggin
2007-01-11  7:54             ` Aubrey
2007-01-11  8:05               ` Roy Huang
2007-01-11 16:45                 ` Linus Torvalds
2007-01-17  4:29                   ` Aubrey Li
2007-01-12  2:12                 ` Aubrey
2007-01-12  2:47                   ` Nick Piggin
2007-01-12  3:59                   ` Roy Huang
2007-01-11  8:12               ` Nick Piggin
2007-01-11  8:49                 ` Roy Huang
2007-01-11  9:09                   ` Nick Piggin
2007-01-12  2:48                 ` Bill Davidsen
2007-01-12  4:30                   ` Nick Piggin
2007-01-12  4:46                     ` Linus Torvalds
2007-01-12  4:56                       ` Nick Piggin
2007-01-12  4:58                         ` Nick Piggin
2007-01-12  5:18                         ` Linus Torvalds
2007-01-12  5:22                         ` Aubrey
2007-01-12 14:59                           ` Bill Davidsen
2007-01-13  4:51                             ` Nick Piggin
2007-01-11  6:16     ` Alexander Shishkin
2007-01-11  6:57       ` Aubrey
2007-01-11 12:13   ` Viktor
2007-01-11 15:53     ` Phillip Susi
2007-01-11 16:20     ` Linus Torvalds
2007-01-11 17:13       ` Michael Tokarev
2007-01-11 23:01         ` Phillip Susi
2007-01-11 23:06           ` Hua Zhong
2007-01-12 15:21             ` Phillip Susi
2007-01-20 16:36         ` Denis Vlasenko
2007-01-20 20:55           ` Michael Tokarev
2007-01-20 23:05             ` Denis Vlasenko
2007-01-21 12:09               ` Michael Tokarev
2007-01-21 20:02                 ` Denis Vlasenko
2007-01-22 16:17                   ` Phillip Susi
2007-01-24 21:15                     ` Denis Vlasenko
2007-01-25 15:44                       ` Phillip Susi
2007-01-25 17:38                         ` Denis Vlasenko
2007-01-25 19:28                           ` Phillip Susi
2007-01-25 19:52                             ` Denis Vlasenko
2007-01-25 20:03                               ` Phillip Susi
2007-01-25 20:45                                 ` Michael Tokarev
2007-01-25 21:11                                   ` Denis Vlasenko
2007-01-26 16:02                                     ` Mark Lord
2007-01-26 16:52                                       ` Viktor
2007-01-26 16:58                                       ` Phillip Susi
2007-01-26 17:05                                     ` Phillip Susi
2007-01-26 23:16                                       ` Denis Vlasenko
2007-02-06 20:39                                         ` Pavel Machek
2007-01-26 18:23                                     ` Bill Davidsen
2007-01-26 23:35                                       ` Denis Vlasenko
2007-01-28 15:18                                         ` Bill Davidsen
2007-01-28 17:03                                           ` Denis Vlasenko
2007-01-29 15:43                                             ` Phillip Susi
2007-01-29 17:00                                             ` Andrea Arcangeli
2007-01-30  0:05                                               ` Denis Vlasenko
     [not found]                                               ` <45BE7D99.70200@cfl.rr.com>
     [not found]                                                 ` <20070130023056.GN8030@opteron.random>
     [not found]                                                   ` <45BF65E3.6070102@cfl.rr.com>
     [not found]                                                     ` <20070130164806.GQ8030@opteron.random>
2007-01-30 18:50                                                       ` Phillip Susi
2007-01-30 19:57                                                         ` Andrea Arcangeli
2007-01-30 20:06                                                           ` Andrea Arcangeli
2007-01-30 23:07                                                           ` Phillip Susi
2007-01-31  2:28                                                             ` Andrea Arcangeli
2007-01-31  9:37                                                             ` Michael Tokarev
2007-01-26 15:53                   ` Bill Davidsen
2007-01-11 17:42       ` Alan [this message]
2007-01-11 18:00         ` Linus Torvalds
2007-01-12  7:57       ` dean gaudet
2007-01-12 15:27         ` Phillip Susi
2007-01-12 18:06         ` Linus Torvalds
2007-01-12 20:23           ` Chris Mason
2007-01-12 20:46             ` Michael Tokarev
2007-01-12 20:52               ` Michael Tokarev
2007-01-12 21:03                 ` Michael Tokarev
2007-01-12 21:17                   ` Linus Torvalds
2007-01-12 21:54                     ` Michael Tokarev
2007-01-12 22:09                       ` Linus Torvalds
2007-01-12 22:26                         ` Michael Tokarev
2007-01-12 22:35                         ` Erik Andersen
2007-01-12 22:47                           ` Andrew Morton
2007-01-14  9:11                             ` Nate Diller
2007-01-20 16:45                               ` Denis Vlasenko
2007-01-22  1:47                             ` Andrea Arcangeli
2007-01-13 20:07                     ` Bill Davidsen
2007-01-13 20:27                       ` Michael Tokarev
2007-01-14 15:39                         ` Bill Davidsen
2007-01-12 21:39                   ` Disk Cache, Was: " Zan Lynx
2007-01-12 22:10                     ` Michael Tokarev
2007-01-15 12:11               ` Helge Hafting
2007-01-12 16:59       ` Viktor
2007-01-11 12:45   ` Erik Mouw
2007-01-11  4:51 ` Andrew Morton
2007-01-11  5:06   ` Gerrit Huizenga
2007-01-11 16:09   ` Badari Pulavarty
2007-01-11 12:34 ` linux-os (Dick Johnson)
2007-01-11 13:06   ` Martin Mares
2007-01-11 14:15   ` Jens Axboe
2007-01-12  2:13   ` Bill Davidsen
  -- strict thread matches above, loose matches on Subject: below --
2007-01-17 14:27 Alex Tomas
2007-01-22 15:59 Al Boldi
     [not found] <7BYkO-5OV-17@gated-at.bofh.it>
     [not found] ` <7BYul-6gz-5@gated-at.bofh.it>
     [not found]   ` <7C18X-1zo-5@gated-at.bofh.it>
     [not found]     ` <7C1iw-22q-7@gated-at.bofh.it>
     [not found]       ` <7C1Vb-2Ny-3@gated-at.bofh.it>
     [not found]         ` <7C256-2ZR-27@gated-at.bofh.it>
     [not found]           ` <7C2eE-3rT-15@gated-at.bofh.it>
     [not found]             ` <7C31d-4qb-11@gated-at.bofh.it>
     [not found]               ` <7C3kj-55E-9@gated-at.bofh.it>
2007-01-11 13:20                 ` Bodo Eggert
     [not found]   ` <7C74B-2A4-23@gated-at.bofh.it>
     [not found]     ` <7CaYA-mT-19@gated-at.bofh.it>
     [not found]       ` <7Cpuz-64X-1@gated-at.bofh.it>
     [not found]         ` <7Cz0T-4PH-17@gated-at.bofh.it>
     [not found]           ` <7CBcl-86B-9@gated-at.bofh.it>
     [not found]             ` <7CBvH-52-9@gated-at.bofh.it>
     [not found]               ` <7CBFn-hw-1@gated-at.bofh.it>
     [not found]                 ` <7CBP1-KI-3@gated-at.bofh.it>
     [not found]                   ` <7CBYG-WK-3@gated-at.bofh.it>
2007-01-13 16:53                     ` Bodo Eggert
2007-01-13 19:30                       ` Bill Davidsen
2007-01-14 18:51                         ` Bodo Eggert
     [not found]                     ` <7CXmz-88G-29@gated-at.bofh.it>
     [not found]                       ` <7CXFR-8vZ-15@gated-at.bofh.it>
     [not found]                         ` <7DfMP-2ak-19@gated-at.bofh.it>
2007-01-14 19:39                           ` Bodo Eggert
     [not found]               ` <7DyYK-6lE-3@gated-at.bofh.it>
2007-01-16 20:26                 ` Bodo Eggert
2007-01-17  5:55                   ` Arjan van de Ven
2007-01-17 22:36                     ` Bodo Eggert
     [not found] ` <7HkaQ-2Nb-9@gated-at.bofh.it>
     [not found]   ` <7HDZP-Pv-1@gated-at.bofh.it>
     [not found]     ` <7HIPV-8kp-35@gated-at.bofh.it>
2007-01-27 14:01       ` Bodo Eggert
2007-01-27 14:14         ` Denis Vlasenko
2007-01-28 15:30           ` Bill Davidsen
2007-01-28 17:18             ` Denis Vlasenko

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