From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 8 Jun 2001 03:38:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 8 Jun 2001 03:38:44 -0400 Received: from 196-41-175-253.citec.net ([196.41.175.253]:41109 "EHLO penguin.wetton.prism.co.za") by vger.kernel.org with ESMTP id ; Fri, 8 Jun 2001 03:38:31 -0400 Date: Fri, 8 Jun 2001 09:37:29 +0200 From: Bernd Jendrissek To: Brian D Heaton Cc: linux-kernel@vger.kernel.org Subject: Re: Break 2.4 VM in five easy steps Message-ID: <20010608093729.A11720@prism.co.za> In-Reply-To: <20010607124621.A30328@prism.co.za> <20010607153835.T14203@jessica> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0pre3us In-Reply-To: <20010607153835.T14203@jessica> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Thu, Jun 07, 2001 at 03:38:35PM -0600, Brian D Heaton wrote: > Maybe i'm missing something. I just tried this (with the 262144k/1 > and 128k/2048 params) and my results are within .1s of each other. This is > without any special patches. Am I doing something wrong???? Oh, I don't mean the time elapsed, It's that nothing _else_ can happen while dd is hogging the kernel. > Oh yes - > > SMP - dual PIII866/133 Yes, this is what you are doing wrong ;) My hypothesis is that in your case, one cpu gets pegged copying pages from /dev/zero into dd's buffer, while the other cpu can do things like updating mouse cursors, run setiathome, etc. What happens if you do *two* dd-tortures with huge buffers at the same time? And then, please don't happen to have a quad box! I don't know if my symptom (loss of interactivity on heavy writing) is related to swapoff -a causing the same symptom on deeply-swapped boxes. BTW keep in mind my 4-liner is based more on voodoo than on analysis. Bernd Jendrissek -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE7IICU/FmLrNfLpjMRAnpTAJ48/jAFxZqfxUf2NXT0O542KDbNOwCfaoZo Q2xaNE4GBqnbn/cl2vrRxLc= =4sGO -----END PGP SIGNATURE-----