From: Howard Chu <hyc-aQkYFu9vm6AAvxtiuMwx3w@public.gmane.org>
To: General Discussion of SQLite Database
<sqlite-users-CzDROfG0BjIdnm+yROfE0A@public.gmane.org>
Cc: Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>,
drh-X1OJI8nnyKUAvxtiuMwx3w@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Vladislav Bolkhovitin <vst-d+Crzxg7Rs0@public.gmane.org>,
Alan Cox <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
Subject: Re: light weight write barriers
Date: Thu, 01 Nov 2012 17:38:25 -0700 [thread overview]
Message-ID: <50931601.4060102@symas.com> (raw)
In-Reply-To: <20121101212418.140e3a82-38n7/U1jhRXW96NNrWNlrekiAK3p4hvP@public.gmane.org>
Alan Cox wrote:
>> How about that recently preliminary infrastructure to send ORDERED commands
>> instead of queue draining was deleted from the kernel, because "there's no
>> difference where to drain the queue, on the kernel or the storage side"?
>
> Send patches.
Isn't any type of kernel-side ordering an exercise in futility, since
a) the kernel has no knowledge of the disk's actual geometry
b) most drives will internally re-order requests anyway
c) cheap drives won't support barriers
Even assuming the drives honored all your requests without lying, how would
you really want this behavior exposed? From the userland perspective, there
are very few apps that care. Probably only transactional databases, really.
As a DB author, I'm not sure I'd be keen on this as an open() or fcntl()
option. Databases that really care would be on dedicated filesystems and/or
devices, so per-file control would be tedious. You would most likely want to
say "all writes to this string of devices should be order-preserving" and
forget about it. With that guarantee, a careful writer can have perfectly
intact data structures all the time, without ever slowing down for a fsync.
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
WARNING: multiple messages have this Message-ID (diff)
From: Howard Chu <hyc@symas.com>
To: General Discussion of SQLite Database <sqlite-users@sqlite.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Vladislav Bolkhovitin <vst@vlnb.net>,
"Theodore Ts'o" <tytso@mit.edu>,
drh@hwaci.com, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [sqlite] light weight write barriers
Date: Thu, 01 Nov 2012 17:38:25 -0700 [thread overview]
Message-ID: <50931601.4060102@symas.com> (raw)
In-Reply-To: <20121101212418.140e3a82@pyramind.ukuu.org.uk>
Alan Cox wrote:
>> How about that recently preliminary infrastructure to send ORDERED commands
>> instead of queue draining was deleted from the kernel, because "there's no
>> difference where to drain the queue, on the kernel or the storage side"?
>
> Send patches.
Isn't any type of kernel-side ordering an exercise in futility, since
a) the kernel has no knowledge of the disk's actual geometry
b) most drives will internally re-order requests anyway
c) cheap drives won't support barriers
Even assuming the drives honored all your requests without lying, how would
you really want this behavior exposed? From the userland perspective, there
are very few apps that care. Probably only transactional databases, really.
As a DB author, I'm not sure I'd be keen on this as an open() or fcntl()
option. Databases that really care would be on dedicated filesystems and/or
devices, so per-file control would be tedious. You would most likely want to
say "all writes to this string of devices should be order-preserving" and
forget about it. With that guarantee, a careful writer can have perfectly
intact data structures all the time, without ever slowing down for a fsync.
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
next prev parent reply other threads:[~2012-11-02 0:38 UTC|newest]
Thread overview: 146+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <415E76CC-A53D-4643-88AB-3D7D7DC56F98@dubeyko.com>
2012-10-06 13:54 ` [PATCH 00/16] f2fs: introduce flash-friendly file system Vyacheslav Dubeyko
2012-10-06 20:06 ` Jaegeuk Kim
2012-10-07 7:09 ` Marco Stornelli
2012-10-07 9:31 ` Jaegeuk Kim
2012-10-07 9:31 ` Jaegeuk Kim
2012-10-07 12:08 ` Vyacheslav Dubeyko
2012-10-07 12:08 ` Vyacheslav Dubeyko
2012-10-08 8:25 ` Jaegeuk Kim
2012-10-08 8:25 ` Jaegeuk Kim
2012-10-08 9:59 ` Namjae Jeon
2012-10-08 9:59 ` Namjae Jeon
2012-10-08 10:52 ` Jaegeuk Kim
2012-10-08 11:21 ` Namjae Jeon
2012-10-08 12:11 ` Jaegeuk Kim
2012-10-09 3:52 ` Namjae Jeon
2012-10-09 8:00 ` Jaegeuk Kim
2012-10-09 8:31 ` Lukáš Czerner
2012-10-09 10:45 ` Jaegeuk Kim
2012-10-09 10:45 ` Jaegeuk Kim
2012-10-09 11:01 ` Lukáš Czerner
2012-10-09 12:01 ` Jaegeuk Kim
2012-10-09 12:39 ` Lukáš Czerner
2012-10-09 13:10 ` Jaegeuk Kim
2012-10-09 21:20 ` Dave Chinner
2012-10-09 21:20 ` Dave Chinner
2012-10-10 2:32 ` Jaegeuk Kim
2012-10-10 4:53 ` Theodore Ts'o
2012-10-10 4:53 ` Theodore Ts'o
2012-10-12 20:55 ` Arnd Bergmann
2012-10-10 10:36 ` David Woodhouse
2012-10-12 20:58 ` Arnd Bergmann
2012-10-13 4:26 ` Namjae Jeon
2012-10-13 12:37 ` Jaegeuk Kim
2012-10-13 12:37 ` Jaegeuk Kim
2012-10-17 11:12 ` Namjae Jeon
[not found] ` <000001cdacef$b2f6eaa0$18e4bfe0$%kim@samsung.com>
2012-10-18 13:39 ` Vyacheslav Dubeyko
2012-10-18 22:14 ` Jaegeuk Kim
2012-10-19 9:20 ` NeilBrown
2012-10-08 19:22 ` Vyacheslav Dubeyko
2012-10-09 7:08 ` Jaegeuk Kim
2012-10-09 7:08 ` Jaegeuk Kim
2012-10-09 19:53 ` Jooyoung Hwang
2012-10-09 19:53 ` Jooyoung Hwang
2012-10-10 8:05 ` Vyacheslav Dubeyko
2012-10-10 9:02 ` Theodore Ts'o
2012-10-10 11:52 ` SQLite on flash (was: [PATCH 00/16] f2fs: introduce flash-friendly file system) Clemens Ladisch
[not found] ` <50756199.1090103-P6GI/4k7KOmELgA04lAiVw@public.gmane.org>
2012-10-10 12:47 ` Richard Hipp
2012-10-10 17:17 ` light weight write barriers Andi Kleen
[not found] ` <m2fw5mtffg.fsf_-_-Vw/NltI1exuRpAAqCnN02g@public.gmane.org>
2012-10-10 17:48 ` Richard Hipp
[not found] ` <CALwJ=MyR+nU3zqi3V3JMuEGNwd8FUsw9xLACJvd0HoBv3kRi0w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-10-11 16:38 ` Nico Williams
2012-10-11 16:38 ` [sqlite] " Nico Williams
[not found] ` <CAK3OfOi3E1ePfzWjq1epFaXsjtn8V_=r3h+PG6ankWW2fOr6GA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-10-11 16:48 ` Nico Williams
2012-10-11 16:48 ` [sqlite] " Nico Williams
2012-10-11 16:32 ` 杨苏立 Yang Su Li
2012-10-11 16:32 ` [sqlite] " 杨苏立 Yang Su Li
2012-10-11 17:41 ` Christoph Hellwig
2012-10-23 19:53 ` Vladislav Bolkhovitin
[not found] ` <5086F5A7.9090406-d+Crzxg7Rs0@public.gmane.org>
2012-10-24 21:17 ` Nico Williams
2012-10-24 21:17 ` [sqlite] " Nico Williams
2012-10-24 22:03 ` david
[not found] ` <alpine.DEB.2.02.1210241447210.8519-Z4YwzcCRHZnr5h6Zg1Auow@public.gmane.org>
2012-10-25 0:20 ` Nico Williams
2012-10-25 0:20 ` [sqlite] " Nico Williams
2012-10-25 1:04 ` david
[not found] ` <alpine.DEB.2.02.1210241748180.8519-Z4YwzcCRHZnr5h6Zg1Auow@public.gmane.org>
2012-10-25 5:18 ` Nico Williams
2012-10-25 5:18 ` [sqlite] " Nico Williams
2012-10-25 6:02 ` Theodore Ts'o
2012-10-25 6:58 ` david
[not found] ` <alpine.DEB.2.02.1210242331060.31862-Z4YwzcCRHZnr5h6Zg1Auow@public.gmane.org>
2012-10-25 14:03 ` Theodore Ts'o
2012-10-25 14:03 ` [sqlite] " Theodore Ts'o
[not found] ` <20121025140327.GB13562-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2012-10-25 18:03 ` david-gFPdbfVZQbY
2012-10-25 18:03 ` [sqlite] " david
[not found] ` <alpine.DEB.2.02.1210251048280.8519-Z4YwzcCRHZnr5h6Zg1Auow@public.gmane.org>
2012-10-25 18:29 ` Theodore Ts'o
2012-10-25 18:29 ` [sqlite] " Theodore Ts'o
2012-11-05 20:03 ` Pavel Machek
[not found] ` <20121105200348.GB15821-5NIqAleC692hcjWhqY66xCZi+YwRKgec@public.gmane.org>
2012-11-05 22:04 ` Theodore Ts'o
2012-11-05 22:04 ` [sqlite] " Theodore Ts'o
[not found] ` <20121105220440.GB25378-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2012-11-05 22:37 ` Richard Hipp
[not found] ` <CALwJ=Mx-uEFLXK2wywekk=0dwrwVFb68wocnH9bjXJmHRsJx3w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-05 23:00 ` Theodore Ts'o
2012-11-05 23:00 ` [sqlite] " Theodore Ts'o
2012-10-30 23:49 ` Nico Williams
2012-10-25 5:42 ` Theodore Ts'o
2012-10-25 7:11 ` david
2012-10-27 1:52 ` Vladislav Bolkhovitin
2012-10-25 5:14 ` Theodore Ts'o
2012-10-25 13:03 ` Alan Cox
[not found] ` <20121025140325.49cd7c79-38n7/U1jhRXW96NNrWNlrekiAK3p4hvP@public.gmane.org>
2012-10-25 13:50 ` Theodore Ts'o
2012-10-25 13:50 ` [sqlite] " Theodore Ts'o
2012-10-27 1:55 ` Vladislav Bolkhovitin
2012-10-27 1:54 ` Vladislav Bolkhovitin
[not found] ` <508B3EED.2080003-d+Crzxg7Rs0@public.gmane.org>
2012-10-27 4:44 ` Theodore Ts'o
2012-10-27 4:44 ` [sqlite] " Theodore Ts'o
2012-10-30 22:22 ` Vladislav Bolkhovitin
[not found] ` <5090532D.4050902-d+Crzxg7Rs0@public.gmane.org>
2012-10-31 9:54 ` Alan Cox
2012-10-31 9:54 ` [sqlite] " Alan Cox
2012-11-01 20:18 ` Vladislav Bolkhovitin
[not found] ` <5092D90F.7020105-d+Crzxg7Rs0@public.gmane.org>
2012-11-01 21:24 ` Alan Cox
2012-11-01 21:24 ` [sqlite] " Alan Cox
2012-11-02 0:15 ` Vladislav Bolkhovitin
[not found] ` <20121101212418.140e3a82-38n7/U1jhRXW96NNrWNlrekiAK3p4hvP@public.gmane.org>
2012-11-02 0:38 ` Howard Chu [this message]
2012-11-02 0:38 ` Howard Chu
[not found] ` <50931601.4060102-aQkYFu9vm6AAvxtiuMwx3w@public.gmane.org>
2012-11-02 12:24 ` Richard Hipp
2012-11-13 3:41 ` [sqlite] " Vladislav Bolkhovitin
2012-11-02 12:33 ` Alan Cox
2012-11-02 12:33 ` [sqlite] " Alan Cox
2012-11-13 3:41 ` Vladislav Bolkhovitin
[not found] ` <50A1C15E.2080605-d+Crzxg7Rs0@public.gmane.org>
2012-11-13 17:40 ` Alan Cox
2012-11-13 17:40 ` [sqlite] " Alan Cox
[not found] ` <20121113174000.6457a68b-38n7/U1jhRXW96NNrWNlrekiAK3p4hvP@public.gmane.org>
2012-11-13 19:13 ` Nico Williams
2012-11-13 19:13 ` [sqlite] " Nico Williams
2012-11-15 1:17 ` Vladislav Bolkhovitin
[not found] ` <50A442AF.9020407-d+Crzxg7Rs0@public.gmane.org>
2012-11-15 12:07 ` David Lang
2012-11-15 12:07 ` [sqlite] " David Lang
[not found] ` <alpine.DEB.2.02.1211150353080.32408-UEhY+ZBZOcqqLGM74eQ/YA@public.gmane.org>
2012-11-15 16:14 ` 杨苏立 Yang Su Li
2012-11-17 5:02 ` [sqlite] " Vladislav Bolkhovitin
2012-11-17 5:02 ` Vladislav Bolkhovitin
2012-11-16 15:06 ` Howard Chu
2012-11-16 15:06 ` [sqlite] " Howard Chu
2012-11-16 15:31 ` Ric Wheeler
[not found] ` <50A65C68.6080001-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-11-16 15:54 ` Howard Chu
2012-11-16 15:54 ` [sqlite] " Howard Chu
2012-11-16 18:03 ` Ric Wheeler
2012-11-16 18:03 ` Ric Wheeler
[not found] ` <50A65681.8000204-aQkYFu9vm6AAvxtiuMwx3w@public.gmane.org>
2012-11-16 19:14 ` David Lang
2012-11-16 19:14 ` [sqlite] " David Lang
2012-11-17 5:02 ` Vladislav Bolkhovitin
2012-11-15 17:06 ` Ryan Johnson
2012-11-15 17:06 ` [sqlite] " Ryan Johnson
2012-11-15 22:35 ` Chris Friesen
2012-11-17 5:02 ` Vladislav Bolkhovitin
2012-11-20 1:23 ` Vladislav Bolkhovitin
2012-11-26 20:05 ` Nico Williams
[not found] ` <CAK3OfOjD4XBGfu3cnMwTvCfec0Lvg3zrO16+pXtiFF4UWpFjDw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-29 2:15 ` Vladislav Bolkhovitin
2012-11-29 2:15 ` [sqlite] " Vladislav Bolkhovitin
2012-11-15 1:16 ` Vladislav Bolkhovitin
2012-11-13 3:37 ` Vladislav Bolkhovitin
2012-11-11 4:25 ` 杨苏立 Yang Su Li
2012-11-13 3:42 ` [sqlite] " Vladislav Bolkhovitin
2012-10-10 7:57 ` [PATCH 00/16] f2fs: introduce flash-friendly file system Vyacheslav Dubeyko
2012-10-10 9:43 ` Jaegeuk Kim
2012-10-11 3:14 ` Namjae Jeon
[not found] ` <CAN863PuyMkSZtZCvqX+kwei9v=rnbBYVYr3TqBXF_6uxwJe2_Q@mail.gmail.com>
2012-10-17 11:13 ` Namjae Jeon
2012-10-17 23:06 ` Changman Lee
2012-10-12 12:30 ` Vyacheslav Dubeyko
2012-10-12 14:25 ` Jaegeuk Kim
2012-10-07 10:15 ` Vyacheslav Dubeyko
2012-10-07 10:15 ` Vyacheslav Dubeyko
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