Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965389AbXATVMo (ORCPT ); Sat, 20 Jan 2007 16:12:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965390AbXATVMo (ORCPT ); Sat, 20 Jan 2007 16:12:44 -0500 Received: from nf-out-0910.google.com ([64.233.182.189]:28775 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965389AbXATVMo (ORCPT ); Sat, 20 Jan 2007 16:12:44 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=A5Jo7kwRycm03RDPIooYIEfocInxItnFkYdfuIBqd424Tp9OU8SwaKs0uX9NmbZOBu2mwqCHR+rYPpdrkxvk6sZuLgKbcd8FsGbysH+bGEJfpuF3QHSvBRLWwS4kVU7UZsLdsU0TKPZjbgQsy/eK9bvgAe0nTitZxFmtKn+9Ru4= Message-ID: <8355959a0701201312r9a3aac4ufd151ca18ef7e64e@mail.gmail.com> Date: Sun, 21 Jan 2007 02:42:42 +0530 From: "Sunil Naidu" To: "Tim Schmielau" Subject: Re: Abysmal disk performance, how to debug? Cc: "=?ISO-8859-1?Q?Ismail_D=F6nmez?=" , "Willy Tarreau" , linux-kernel@vger.kernel.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200701201920.54620.ismail@pardus.org.tr> <20070120174503.GZ24090@1wt.eu> <200701201952.54714.ismail@pardus.org.tr> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1600 Lines: 58 On 1/21/07, Tim Schmielau wrote: > > Note that these dd "benchmarks" are completely bogus, because the data > doesn't actually get written to disk in that time. For some enlightening > data, try > > time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024; time sync > > The dd returns as soon as all data could be buffered in RAM. Only sync > 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. I am still getting better I feel: [sukhoi@Typhoon ~]$ time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024; time sync 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB) copied, 19.5007 seconds, 55.1 MB/s real 0m20.439s user 0m0.004s sys 0m4.535s real 0m4.625s user 0m0.000s sys 0m0.125s [sukhoi@Typhoon ~]$ 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, 20.8707 seconds, 51.4 MB/s real 0m22.449s user 0m0.002s sys 0m4.922s Linux used here is not 2.6.20-rc5, but it's a FC6 2.6.19 binary. Shall post the results with 2.6.20-rc5. BTW, does the results vary with a customized kernel (configured w.r.t Processor & Hardware) than a generic kernel like FC6? Are there any other such test cases? > > Tim > Thanks, ~Akula2 - 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/