Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965360AbXATUQY (ORCPT ); Sat, 20 Jan 2007 15:16:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965368AbXATUQY (ORCPT ); Sat, 20 Jan 2007 15:16:24 -0500 Received: from ns2.uludag.org.tr ([193.140.100.220]:38243 "EHLO uludag.org.tr" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965360AbXATUQX convert rfc822-to-8bit (ORCPT ); Sat, 20 Jan 2007 15:16:23 -0500 From: Ismail =?utf-8?q?D=C3=B6nmez?= Organization: TUBITAK/UEKAE To: Tim Schmielau Subject: Re: Abysmal disk performance, how to debug? Date: Sat, 20 Jan 2007 22:16:15 +0200 User-Agent: KMail/1.9.5 Cc: Willy Tarreau , linux-kernel@vger.kernel.org References: <200701201920.54620.ismail@pardus.org.tr> <200701201952.54714.ismail@pardus.org.tr> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200701202216.16637.ismail@pardus.org.tr> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1011 Lines: 29 20 Oca 2007 Cts 22:10 tarihinde, Tim Schmielau şunları yazmıştı: [...] > > Note that these dd "benchmarks" are completely bogus, because the data=20 > doesn't actually get written to disk in that time. For some enlightening=20 > data, try > > time dd if=3D/dev/zero of=3D/tmp/1GB bs=3D1M count=3D1024; time sync > > The dd returns as soon as all data could be buffered in RAM. Only sync=20 > will show how long it takes to actually write out the data to disk. > also explains why you see better results is writeout starts earlier. Still not that bad: [~]> time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024;sync 1024+0 records in 1024+0 records out 1073741824 bytes (1,1 GB) copied, 53,3194 s, 20,1 MB/s real 0m53.517s user 0m0.003s sys 0m3.193s - 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/