From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268458AbUHLIIb (ORCPT ); Thu, 12 Aug 2004 04:08:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268459AbUHLIIb (ORCPT ); Thu, 12 Aug 2004 04:08:31 -0400 Received: from imap.gmx.net ([213.165.64.20]:33476 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S268458AbUHLII3 (ORCPT ); Thu, 12 Aug 2004 04:08:29 -0400 X-Authenticated: #4512188 Message-ID: <411B2576.6010903@gmx.de> Date: Thu, 12 Aug 2004 10:08:22 +0200 From: "Prakash K. Cheemplavam" User-Agent: Mozilla Thunderbird 0.7.3 (X11/20040805) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Con Kolivas CC: linux kernel mailing list Subject: Re: Scheduler fairness problem on 2.6 series References: <20040811022143.4892.qmail@web13910.mail.yahoo.com> <4119F3D9.7040708@gmx.de> <411A024B.6060100@kolivas.org> <411A0B71.4030503@gmx.de> <411A71F1.3090504@gmx.de> <411AAEDA.9070601@kolivas.org> In-Reply-To: <411AAEDA.9070601@kolivas.org> X-Enigmail-Version: 0.85.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Con Kolivas wrote: | Prakash K. Cheemplavam wrote: | |> 124910 9.8170 vmlinux tcp_poll |> 123356 9.6949 vmlinux sys_select |> 85634 6.7302 vmlinux do_select |> 71858 5.6475 vmlinux sysenter_past_esp |> 62093 4.8801 vmlinux kfree |> 51658 4.0600 vmlinux __copy_to_user_ll |> 37495 2.9468 vmlinux max_select_fd |> 36949 2.9039 vmlinux __kmalloc |> 22700 1.7841 vmlinux __copy_from_user_ll |> 14587 1.1464 vmlinux do_gettimeofday |> | It looks like your select timeouts are too short and when the cpu load | goes up they repeatedly timeout wasting cpu cycles. | I quote from `man select_tut` under the section SELECT LAW: | | 1. You should always try use select without a timeout. Your program | should have nothing to do if there is no data available. Code | that depends on timeouts is not usually portable and difficult | to debug. | Thanks for your explanation. I cannot do anything about it, as it is mpich related. So I'll ask them if they could change its behaviour a bit so that it eats less CPU on a single CPU machine. Cheers, Prakash -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFBGyV1xU2n/+9+t5gRAqHEAJ9hW/AJYtMenL6mXQ4JZYvTvRrRkgCdHwQD LbJ1MYJ/pbpNbrT8vvlD8uI= =9AUE -----END PGP SIGNATURE-----