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Re: O_DIRECT question

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From: Martin Mares
Subject: Re: O_DIRECT question
Date: Thursday, January 11, 2007 - 6:06 am

Hello!


Incidentally, I was writing an external-memory radix-sort some time ago
and it turned out that writing to 256 files at once is much faster with
O_DIRECT than through the page cache, very likely because the page cache
is flushing pages in essentially random order. Tweaking VM parameters
and block device queue size helped, but only a little.

				Have a nice fortnight
-- 
Martin `MJ' Mares                          <mj@ucw.cz>   http://mj.ucw.cz/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
Linux vs. Windows is a no-WIN situation.
-
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Messages in current thread:
O_DIRECT question, Aubrey, (Wed Jan 10, 7:57 pm)
Re: O_DIRECT question, Linus Torvalds, (Wed Jan 10, 8:05 pm)
Re: O_DIRECT question, Linus Torvalds, (Wed Jan 10, 8:15 pm)
Re: O_DIRECT question, Andrew Morton, (Wed Jan 10, 9:51 pm)
Re: O_DIRECT question , Gerrit Huizenga, (Wed Jan 10, 10:06 pm)
Re: O_DIRECT question, Aubrey, (Wed Jan 10, 10:50 pm)
Re: O_DIRECT question, Andrew Morton, (Wed Jan 10, 11:06 pm)
Re: O_DIRECT question, Nick Piggin, (Wed Jan 10, 11:09 pm)
Re: O_DIRECT question, Alexander Shishkin, (Wed Jan 10, 11:16 pm)
Re: O_DIRECT question, Aubrey, (Wed Jan 10, 11:45 pm)
Re: O_DIRECT question, Andrew Morton, (Wed Jan 10, 11:57 pm)
Re: O_DIRECT question, Aubrey, (Wed Jan 10, 11:57 pm)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 12:05 am)
Re: O_DIRECT question, Aubrey, (Thu Jan 11, 12:54 am)
Re: O_DIRECT question, Roy Huang, (Thu Jan 11, 1:05 am)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 1:12 am)
Re: O_DIRECT question, Roy Huang, (Thu Jan 11, 1:49 am)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 2:09 am)
Re: O_DIRECT question, Viktor, (Thu Jan 11, 5:13 am)
Re: O_DIRECT question, linux-os (Dick Johnson), (Thu Jan 11, 5:34 am)
Re: O_DIRECT question, Erik Mouw, (Thu Jan 11, 5:45 am)
Re: O_DIRECT question, Martin Mares, (Thu Jan 11, 6:06 am)
Re: O_DIRECT question, Jens Axboe, (Thu Jan 11, 7:15 am)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 8:50 am)
Re: O_DIRECT question, Phillip Susi, (Thu Jan 11, 8:53 am)
Re: O_DIRECT question, Badari Pulavarty, (Thu Jan 11, 9:09 am)
Re: O_DIRECT question, Aubrey, (Thu Jan 11, 9:19 am)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 9:20 am)
Re: O_DIRECT question, bert hubert, (Thu Jan 11, 9:23 am)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 9:45 am)
Re: O_DIRECT question, Xavier Bestel, (Thu Jan 11, 9:52 am)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 10:04 am)
Re: O_DIRECT question, Michael Tokarev, (Thu Jan 11, 10:13 am)
Re: O_DIRECT question, Alan, (Thu Jan 11, 10:42 am)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 11:00 am)
Re: O_DIRECT question, Trond Myklebust, (Thu Jan 11, 11:41 am)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 12:00 pm)
Re: O_DIRECT question, Trond Myklebust, (Thu Jan 11, 12:49 pm)
Re: O_DIRECT question, Phillip Susi, (Thu Jan 11, 4:01 pm)
RE: O_DIRECT question, Hua Zhong, (Thu Jan 11, 4:06 pm)
Re: O_DIRECT question, Aubrey, (Thu Jan 11, 7:12 pm)
Re: O_DIRECT question, Bill Davidsen, (Thu Jan 11, 7:13 pm)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 7:47 pm)
Re: O_DIRECT question, Bill Davidsen, (Thu Jan 11, 7:48 pm)
Re: O_DIRECT question, Roy Huang, (Thu Jan 11, 8:59 pm)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 9:30 pm)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 9:46 pm)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 9:56 pm)
Re: O_DIRECT question, Nick Piggin, (Thu Jan 11, 9:58 pm)
Re: O_DIRECT question, Linus Torvalds, (Thu Jan 11, 10:18 pm)
Re: O_DIRECT question, Aubrey, (Thu Jan 11, 10:22 pm)
Re: O_DIRECT question, dean gaudet, (Fri Jan 12, 12:57 am)
Re: O_DIRECT question, Bill Davidsen, (Fri Jan 12, 7:59 am)
Re: O_DIRECT question, Phillip Susi, (Fri Jan 12, 8:21 am)
Re: O_DIRECT question, Phillip Susi, (Fri Jan 12, 8:27 am)
Re: O_DIRECT question, Viktor, (Fri Jan 12, 9:59 am)
Re: O_DIRECT question, Viktor, (Fri Jan 12, 10:03 am)
Re: O_DIRECT question, Linus Torvalds, (Fri Jan 12, 11:06 am)
Re: O_DIRECT question, Chris Mason, (Fri Jan 12, 1:23 pm)
Re: O_DIRECT question, Michael Tokarev, (Fri Jan 12, 1:46 pm)
Re: O_DIRECT question, Michael Tokarev, (Fri Jan 12, 1:52 pm)
Re: O_DIRECT question, Michael Tokarev, (Fri Jan 12, 2:03 pm)
Re: O_DIRECT question, Linus Torvalds, (Fri Jan 12, 2:17 pm)
Disk Cache, Was: O_DIRECT question, Zan Lynx, (Fri Jan 12, 2:39 pm)
Re: O_DIRECT question, Michael Tokarev, (Fri Jan 12, 2:54 pm)
Re: O_DIRECT question, Linus Torvalds, (Fri Jan 12, 3:09 pm)
Re: Disk Cache, Was: O_DIRECT question, Michael Tokarev, (Fri Jan 12, 3:10 pm)
Re: O_DIRECT question, Michael Tokarev, (Fri Jan 12, 3:26 pm)
Re: O_DIRECT question, Erik Andersen, (Fri Jan 12, 3:35 pm)
Re: O_DIRECT question, Andrew Morton, (Fri Jan 12, 3:47 pm)
Re: O_DIRECT question, Nick Piggin, (Fri Jan 12, 9:51 pm)
Re: O_DIRECT question, Bill Davidsen, (Sat Jan 13, 1:07 pm)
Re: O_DIRECT question, Michael Tokarev, (Sat Jan 13, 1:27 pm)
Re: O_DIRECT question, Nate Diller, (Sun Jan 14, 2:11 am)
Re: O_DIRECT question, Bill Davidsen, (Sun Jan 14, 8:39 am)
Re: O_DIRECT question, Helge Hafting, (Mon Jan 15, 5:11 am)
Re: O_DIRECT question, Jörn, (Mon Jan 15, 8:41 pm)
Re: O_DIRECT question, Aubrey Li, (Tue Jan 16, 9:29 pm)
Re: O_DIRECT question, Denis Vlasenko, (Sat Jan 20, 9:19 am)
Re: O_DIRECT question, Denis Vlasenko, (Sat Jan 20, 9:36 am)
Re: O_DIRECT question, Denis Vlasenko, (Sat Jan 20, 9:45 am)
Re: O_DIRECT question, Michael Tokarev, (Sat Jan 20, 1:55 pm)
Re: O_DIRECT question, Denis Vlasenko, (Sat Jan 20, 4:05 pm)
Re: O_DIRECT question, Michael Tokarev, (Sun Jan 21, 5:09 am)
Re: O_DIRECT question, Denis Vlasenko, (Sun Jan 21, 1:02 pm)
Re: O_DIRECT question, Andrea Arcangeli, (Sun Jan 21, 6:47 pm)
Re: O_DIRECT question, Phillip Susi, (Mon Jan 22, 8:52 am)
Re: O_DIRECT question, Phillip Susi, (Mon Jan 22, 9:17 am)
Re: O_DIRECT question, Denis Vlasenko, (Wed Jan 24, 2:15 pm)
Re: O_DIRECT question, Phillip Susi, (Thu Jan 25, 8:44 am)
Re: O_DIRECT question, Denis Vlasenko, (Thu Jan 25, 10:38 am)
Re: O_DIRECT question, Phillip Susi, (Thu Jan 25, 12:28 pm)
Re: O_DIRECT question, Denis Vlasenko, (Thu Jan 25, 12:52 pm)
Re: O_DIRECT question, Phillip Susi, (Thu Jan 25, 1:03 pm)
Re: O_DIRECT question, Michael Tokarev, (Thu Jan 25, 1:45 pm)
Re: O_DIRECT question, Denis Vlasenko, (Thu Jan 25, 2:11 pm)
Re: O_DIRECT question, Bill Davidsen, (Fri Jan 26, 8:53 am)
Re: O_DIRECT question, Mark Lord, (Fri Jan 26, 9:02 am)
Re: O_DIRECT question, Viktor, (Fri Jan 26, 9:52 am)
Re: O_DIRECT question, Phillip Susi, (Fri Jan 26, 9:58 am)
Re: O_DIRECT question, Phillip Susi, (Fri Jan 26, 10:05 am)
Re: O_DIRECT question, Bill Davidsen, (Fri Jan 26, 11:23 am)
Re: O_DIRECT question, Denis Vlasenko, (Fri Jan 26, 4:16 pm)
Re: O_DIRECT question, Denis Vlasenko, (Fri Jan 26, 4:35 pm)
Re: O_DIRECT question, Bill Davidsen, (Sun Jan 28, 8:18 am)
Re: O_DIRECT question, Denis Vlasenko, (Sun Jan 28, 10:03 am)
Re: O_DIRECT question, Phillip Susi, (Mon Jan 29, 8:43 am)
Re: O_DIRECT question, Andrea Arcangeli, (Mon Jan 29, 10:00 am)
Re: O_DIRECT question, Denis Vlasenko, (Mon Jan 29, 5:05 pm)
Re: O_DIRECT question, Pavel Machek, (Tue Feb 6, 1:39 pm)