From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Matthew Wilcox <matthew@wil.cx>,
Andrew Morton <akpm@linux-foundation.org>,
"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>,
linux-fsdevel@vger.kernel.org
Subject: Re: AIM7 40% regression with 2.6.26-rc1
Date: Wed, 7 May 2008 11:27:21 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.1.10.0805071125090.3024@woody.linux-foundation.org> (raw)
In-Reply-To: <20080507181714.GA14980@elte.hu>
On Wed, 7 May 2008, Ingo Molnar wrote:
>
> [ this patch should in fact be a bit worse, because there's two more
> atomics in the fastpath - the fastpath atomics of the old semaphore
> code. ]
Well, it doesn't have the irq stuff, which is also pretty costly. Also, it
doesn't nest the accesses the same way (with the counts being *inside* the
spinlock and serialized against each other), so I'm not 100% sure you'd
get the same behaviour.
But yes, it certainly has the potential to show the same slowdown. But
it's not a very good patch, since not showing it doesn't really prove
much.
Linus
next prev parent reply other threads:[~2008-05-07 18:27 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1210052904.3453.30.camel@ymzhang>
[not found] ` <20080506114449.GC32591@elte.hu>
2008-05-06 12:09 ` AIM7 40% regression with 2.6.26-rc1 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
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 [this message]
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
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