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From: Phillip Susi <psusi@cfl.rr.com>
To: Denis Vlasenko <vda.linux@googlemail.com>
Cc: Michael Tokarev <mjt@tls.msk.ru>,
	Linus Torvalds <torvalds@osdl.org>, 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@in
Subject: Re: O_DIRECT question
Date: Thu, 25 Jan 2007 14:28:15 -0500	[thread overview]
Message-ID: <45B904CF.1070102@cfl.rr.com> (raw)
In-Reply-To: <200701251838.30796.vda.linux@googlemail.com>

Denis Vlasenko wrote:
> If you opened a file and are doing only O_DIRECT writes, you
> *always* have your written data flushed, by each write().
> How is it different from writes done using
> "normal" write() + fdatasync() pairs?

Because you can do writes async, but not fdatasync ( unless there is an 
async version I don't know about ).

> Ahhh shit, are you saying that fdatasync will wait until writes
> *by all other processes* to thios file will hit the disk?
> Is that thue?


I think all processes yes, but certainly all writes to this file by this 
process.  That means you have to sync for every write, which means you 
block.  Blocking stalls the pipeline.


  reply	other threads:[~2007-01-25 19:28 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 [this message]
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
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
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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