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From: Matthew Wilcox <matthew@wil.cx>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	"J. Bruce Fields" <bfields@citi.umich.edu>,
	"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Alexander Viro <viro@ftp.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org
Subject: Re: AIM7 40% regression with 2.6.26-rc1
Date: Wed, 7 May 2008 10:38:12 -0600	[thread overview]
Message-ID: <20080507163811.GY19219@parisc-linux.org> (raw)
In-Reply-To: <20080506102153.5484c6ac.akpm@linux-foundation.org>

On Tue, May 06, 2008 at 10:21:53AM -0700, Andrew Morton wrote:
> up() seems to be doing wake-one, FIFO which is nice.  Did the
> implementation which we just removed also do that?  Was it perhaps
> accidentally doing LIFO or something like that?

If heavily contended, it could do this.

up() would increment sem->count and cal __up() which would call wake_up()
down() would decrement sem->count.
The unlucky task woken by __up would lose the race and go back to sleep.

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

  parent reply	other threads:[~2008-05-07 16:38 UTC|newest]

Thread overview: 140+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-06  5:48 AIM7 40% regression with 2.6.26-rc1 Zhang, Yanmin
2008-05-06 11:18 ` Matthew Wilcox
2008-05-06 11:44 ` Ingo Molnar
2008-05-06 12:09   ` Matthew Wilcox
2008-05-06 16:23     ` Matthew Wilcox
2008-05-06 16:36       ` Linus Torvalds
2008-05-06 16:42         ` Matthew Wilcox
2008-05-06 16:39           ` Alan Cox
2008-05-06 16:51             ` Matthew Wilcox
2008-05-06 16:45               ` Alan Cox
2008-05-06 17:42               ` Linus Torvalds
2008-05-06 20:28           ` Linus Torvalds
2008-05-06 16:44         ` J. Bruce Fields
2008-05-06 17:21       ` Andrew Morton
2008-05-06 17:31         ` Matthew Wilcox
2008-05-06 17:49           ` Ingo Molnar
2008-05-06 18:07             ` Andrew Morton
2008-05-11 11:11               ` Matthew Wilcox
2008-05-06 17:39         ` Ingo Molnar
2008-05-07  6:49           ` Zhang, Yanmin
2008-05-06 17:45         ` Linus Torvalds
2008-05-07 16:38         ` Matthew Wilcox [this message]
2008-05-07 16:55           ` Linus Torvalds
2008-05-07 17:08             ` Linus Torvalds
2008-05-07 17:16               ` Andrew Morton
2008-05-07 17:27                 ` Linus Torvalds
2008-05-07 17:22               ` Ingo Molnar
2008-05-07 17:25                 ` Ingo Molnar
2008-05-07 17:31                 ` Linus Torvalds
2008-05-07 17:47                   ` Linus Torvalds
2008-05-07 17:49                   ` Ingo Molnar
2008-05-07 18:02                     ` Linus Torvalds
2008-05-07 18:17                       ` Ingo Molnar
2008-05-07 18:27                         ` Linus Torvalds
2008-05-07 18:43                           ` Ingo Molnar
2008-05-07 19:01                             ` Linus Torvalds
2008-05-07 19:09                               ` Ingo Molnar
2008-05-07 19:24                               ` Matthew Wilcox
2008-05-07 19:44                                 ` Linus Torvalds
2008-05-07 20:00                                   ` Oi. NFS people. Read this Matthew Wilcox
2008-05-07 22:10                                     ` Trond Myklebust
2008-05-09  1:43                                       ` J. Bruce Fields
2008-05-08  3:24       ` AIM7 40% regression with 2.6.26-rc1 Zhang, Yanmin
2008-05-08  3:34         ` Linus Torvalds
2008-05-08  4:37           ` Zhang, Yanmin
2008-05-08 14:58             ` Linus Torvalds
2008-05-07  2:11   ` Zhang, Yanmin
2008-05-07  3:41     ` Zhang, Yanmin
2008-05-07  3:59       ` Andrew Morton
2008-05-07  4:46         ` Zhang, Yanmin
2008-05-07  6:26       ` Ingo Molnar
2008-05-07  6:28         ` Ingo Molnar
2008-05-07  7:05           ` Zhang, Yanmin
2008-05-07 11:00       ` Andi Kleen
2008-05-07 11:46         ` Matthew Wilcox
2008-05-07 12:21           ` Andi Kleen
2008-05-07 14:36             ` Linus Torvalds
2008-05-07 14:35               ` Alan Cox
2008-05-07 15:00                 ` Linus Torvalds
2008-05-07 15:02                   ` Linus Torvalds
2008-05-07 14:57               ` Andi Kleen
2008-05-07 15:31                 ` Andrew Morton
2008-05-07 16:22                   ` Matthew Wilcox
2008-05-07 15:19               ` Linus Torvalds
2008-05-07 17:14                 ` Ingo Molnar
2008-05-08  2:44                 ` Zhang, Yanmin
2008-05-08  3:29                   ` Linus Torvalds
2008-05-08  4:08                     ` Zhang, Yanmin
2008-05-08  4:17                       ` Linus Torvalds
2008-05-08 12:01                         ` [patch] speed up / fix the new generic semaphore code (fix AIM7 40% regression with 2.6.26-rc1) Ingo Molnar
2008-05-08 12:28                           ` Ingo Molnar
2008-05-08 14:43                             ` Ingo Molnar
2008-05-08 15:10                               ` [git pull] scheduler fixes Ingo Molnar
2008-05-08 15:33                                 ` Adrian Bunk
2008-05-08 15:41                                   ` Ingo Molnar
2008-05-08 19:42                                     ` Adrian Bunk
2008-05-11 11:03                                 ` Matthew Wilcox
2008-05-11 11:14                                   ` Matthew Wilcox
2008-05-11 11:48                                   ` Matthew Wilcox
2008-05-11 12:50                                     ` Ingo Molnar
2008-05-11 12:52                                       ` Ingo Molnar
2008-05-11 13:02                                         ` Matthew Wilcox
2008-05-11 13:26                                           ` Matthew Wilcox
2008-05-11 14:00                                             ` Ingo Molnar
2008-05-11 14:18                                               ` Matthew Wilcox
2008-05-11 14:42                                                 ` Ingo Molnar
2008-05-11 14:48                                                   ` Matthew Wilcox
2008-05-11 15:19                                                     ` Ingo Molnar
2008-05-11 15:29                                                       ` Matthew Wilcox
2008-05-13 14:11                                                         ` Ingo Molnar
2008-05-13 14:21                                                           ` Matthew Wilcox
2008-05-13 14:42                                                             ` Ingo Molnar
2008-05-13 15:28                                                               ` Matthew Wilcox
2008-05-13 17:13                                                                 ` Ingo Molnar
2008-05-13 17:22                                                                   ` Linus Torvalds
2008-05-13 21:05                                                                     ` Ingo Molnar
2008-05-11 13:54                                           ` Ingo Molnar
2008-05-11 14:22                                             ` Matthew Wilcox
2008-05-11 14:32                                               ` Ingo Molnar
2008-05-11 14:46                                                 ` Matthew Wilcox
2008-05-11 16:47                                                 ` Linus Torvalds
2008-05-11 13:01                                   ` Ingo Molnar
2008-05-11 13:06                                     ` Matthew Wilcox
2008-05-11 13:45                                       ` Ingo Molnar
2008-05-11 14:10                                   ` Sven Wegener
2008-05-08 16:02                             ` [patch] speed up / fix the new generic semaphore code (fix AIM7 40% regression with 2.6.26-rc1) Linus Torvalds
2008-05-08 18:30                               ` Linus Torvalds
2008-05-08 20:19                                 ` Ingo Molnar
2008-05-08 20:27                                   ` Linus Torvalds
2008-05-08 21:45                                     ` Ingo Molnar
2008-05-08 22:02                                       ` Ingo Molnar
2008-05-08 22:55                                       ` Linus Torvalds
2008-05-08 23:07                                         ` Linus Torvalds
2008-05-08 23:14                                           ` Linus Torvalds
2008-05-08 23:16                                         ` Alan Cox
2008-05-08 23:33                                           ` Linus Torvalds
2008-05-08 23:27                                             ` Alan Cox
2008-05-09  6:50                                             ` Ingo Molnar
2008-05-09  8:29                                             ` Andi Kleen
2008-05-08 13:20                           ` Matthew Wilcox
2008-05-08 15:01                             ` Ingo Molnar
2008-05-08 13:56                           ` Arjan van de Ven
2008-05-08  6:43                   ` AIM7 40% regression with 2.6.26-rc1 Ingo Molnar
2008-05-08  6:48                     ` Andrew Morton
2008-05-08  7:14                     ` Zhang, Yanmin
2008-05-08  7:39                       ` Ingo Molnar
2008-05-08  8:44                         ` Zhang, Yanmin
2008-05-08  9:21                           ` Ingo Molnar
2008-05-08  9:29                             ` Ingo Molnar
2008-05-08  9:30                             ` Zhang, Yanmin
2008-05-07 16:20               ` Ingo Molnar
2008-05-07 16:35                 ` Linus Torvalds
2008-05-07 17:05                   ` Ingo Molnar
2008-05-07 17:24                     ` Linus Torvalds
2008-05-07 17:36                       ` Ingo Molnar
2008-05-07 17:55                         ` Linus Torvalds
2008-05-07 17:59                           ` Matthew Wilcox
2008-05-07 18:17                             ` Linus Torvalds
2008-05-07 18:49                               ` Ingo Molnar
2008-05-07 13:59         ` Alan Cox

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