Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753651AbXJ2VpA (ORCPT ); Mon, 29 Oct 2007 17:45:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752410AbXJ2Vox (ORCPT ); Mon, 29 Oct 2007 17:44:53 -0400 Received: from caffeine.csclub.uwaterloo.ca ([129.97.134.17]:54196 "EHLO caffeine.csclub.uwaterloo.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267AbXJ2Vox (ORCPT ); Mon, 29 Oct 2007 17:44:53 -0400 Date: Mon, 29 Oct 2007 17:44:52 -0400 To: Pavel Machek Cc: Rik van Riel , linux-kernel@vger.kernel.org Subject: Re: WANTED: kernel projects for CS students Message-ID: <20071029214452.GA27643@csclub.uwaterloo.ca> References: <20071014190128.6e3cdb44@bree.surriel.com> <20071028180707.GA6111@ucw.cz> <20071029194820.GC27646@csclub.uwaterloo.ca> <20071029201911.GB3537@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071029201911.GB3537@elf.ucw.cz> User-Agent: Mutt/1.5.13 (2006-08-11) From: lsorense@csclub.uwaterloo.ca (Lennart Sorensen) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1498 Lines: 35 On Mon, Oct 29, 2007 at 09:19:11PM +0100, Pavel Machek wrote: > Tell it to your profesor ;-). I don't have one. I graduated 7 years ago. I was just pointing holes in the spec. :) > Not neccessarily but yes, that would be nice, too. If it doesn't it seems the compression feature is going to be rather unpredictable and my optimization would be perfectly within spec and make it pretty much useless. > Yes. Typically for all zeros. It will be similar for > highly-compressible data (pictures, timetables, ....) That would make it tricky to say if you should ever skip compression due to cpu load. There is a chance cpu load would be better off by doing the compression. > root@amd:/data/tmp# time ( cat /dev/zero | head -c 100000000 > delme; sync ) > 0.04user 0.48system 6.52 (0m6.521s) elapsed 7.97%CPU > root@amd:/data/tmp# time ( cat /dev/zero | head -c 100000000 > delme; sync ) > 0.05user 0.61system 6.33 (0m6.333s) elapsed 10.42%CPU > root@amd:/data/tmp# time ( cat /dev/zero | head -c 100000000 | gzip - > delme; sync ) > 1.57user 0.32system 1.74 (0m1.749s) elapsed 100.00%CPU > root@amd:/data/tmp# time ( cat /dev/zero | head -c 100000000 | gzip - > delme; sync ) > 1.61user 0.18system 1.65 (0m1.652s) elapsed 100.00%CPU -- Len Sorensen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/