From: Andrew Morton <andrewm@uow.edu.au>
To: Andi Kleen <ak@suse.de>
Cc: Alexander Viro <viro@math.psu.edu>,
"Jeff V. Merkey" <jmerkey@timpanogas.org>,
kumon@flab.fujitsu.co.jp, Rik van Riel <riel@conectiva.com.br>,
linux-kernel@vger.kernel.org
Subject: Re: Negative scalability by removal of lock_kernel()?(Was: Strange performance behavior of 2.4.0-test9)
Date: Fri, 27 Oct 2000 21:23:56 +1100 [thread overview]
Message-ID: <39F957BC.4289FF10@uow.edu.au> (raw)
In-Reply-To: <39F92187.A7621A09@timpanogas.org> <Pine.GSO.4.21.0010270257550.18660-100000@weyl.math.psu.edu>, <Pine.GSO.4.21.0010270257550.18660-100000@weyl.math.psu.edu>; from viro@math.psu.edu on Fri, Oct 27, 2000 at 03:13:33AM -0400 <20001027094613.A18382@gruyere.muc.suse.de>
Andi Kleen wrote:
>
> When you have two CPUs contending on common paths it is better to do:
> [ spinlock stuff ]
Andi, if the lock_kernel() is removed then the first time the CPUs will butt heads is on a semaphore. This is much more expensive.
I bet if acquire_fl_sem() and release_fl_sem() are turned into lock_kernel()/unlock_kernel() then the scalability will come back.
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next prev parent reply other threads:[~2000-10-27 10:25 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200010250736.QAA12373@asami.proc.flab.fujitsu.co.jp>
[not found] ` <Pine.LNX.4.21.0010251242050.943-100000@duckman.distro.conectiva>
[not found] ` <200010260138.KAA17028@asami.proc.flab.fujitsu.co.jp>
[not found] ` <200010261405.XAA19135@asami.proc.flab.fujitsu.co.jp>
2000-10-27 6:24 ` Negative scalability by removal of lock_kernel()? (Was: Strange performance behavior of 2.4.0-test9) kumon
2000-10-27 6:32 ` Negative scalability by removal of lock_kernel()?(Was: " Jeff V. Merkey
2000-10-27 7:13 ` Alexander Viro
2000-10-27 7:46 ` Andi Kleen
2000-10-27 10:23 ` Andrew Morton [this message]
2000-10-27 10:25 ` Andi Kleen
2000-10-27 12:57 ` [PATCH] " kumon
2000-10-28 15:46 ` Andrew Morton
2000-10-28 15:58 ` Andi Kleen
2000-10-28 16:05 ` Jeff Garzik
2000-10-28 16:20 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was: Alan Cox
2000-10-29 19:45 ` dean gaudet
2000-10-30 6:29 ` Andi Kleen
2000-10-30 15:28 ` Andrea Arcangeli
2000-10-30 16:36 ` Rik van Riel
2000-10-30 18:02 ` Andrea Arcangeli
2000-10-28 16:46 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was: Strange performance behavior of 2.4.0-test9) Andrew Morton
2000-10-30 9:27 ` kumon
2000-10-30 15:00 ` Andrew Morton
2000-10-30 23:24 ` dean gaudet
2000-11-04 5:08 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was:Strange " Andrew Morton
2000-11-04 6:23 ` Linus Torvalds
2000-11-04 10:54 ` [PATCH] Re: Negative scalability by removal of Alan Cox
2000-11-04 17:22 ` Linus Torvalds
2000-11-05 16:22 ` Andrea Arcangeli
2000-11-05 20:21 ` dean gaudet
2000-11-05 22:43 ` Alan Cox
2000-11-04 20:03 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was:Strange performance behavior of 2.4.0-test9) dean gaudet
2000-11-04 20:42 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was:Strange Alan Cox
2000-11-04 20:11 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was:Strange performance behavior of 2.4.0-test9) dean gaudet
2000-11-04 20:43 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was:Strange Alan Cox
2000-11-05 4:52 ` dean gaudet
2000-10-31 15:36 ` [PATCH] Re: Negative scalability by removal of lock_kernel()?(Was: Strange performance behavior of 2.4.0-test9) Andrew Morton
2000-11-01 1:02 ` kumon
2000-11-02 11:09 ` kumon
2000-11-02 12:50 ` kumon
2000-11-04 5:07 ` Andrew Morton
2000-10-27 8:17 ` Jeff V. Merkey
2000-10-27 10:11 ` kumon
2000-11-04 5:55 ` Preemptive scheduling of woken-up processes kumon
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