From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752370AbXA0ToS (ORCPT ); Sat, 27 Jan 2007 14:44:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752371AbXA0ToS (ORCPT ); Sat, 27 Jan 2007 14:44:18 -0500 Received: from main.gmane.org ([80.91.229.2]:36663 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752369AbXA0ToR (ORCPT ); Sat, 27 Jan 2007 14:44:17 -0500 X-Injected-Via-Gmane: http://gmane.org/ To: linux-kernel@vger.kernel.org From: Bill Davidsen Subject: Re: Abysmal disk performance, how to debug? Date: Sat, 27 Jan 2007 14:43:04 -0500 Message-ID: <45BBAB48.9060304@tmr.com> References: <200701201920.54620.ismail@pardus.org.tr> <20070120174503.GZ24090@1wt.eu> <200701201952.54714.ismail@pardus.org.tr> <20070120180344.GA23841@1wt.eu> <8355959a0701201144x290362d8ja6cd5bc1408475da@mail.gmail.com> <45B273E4.8040302@seclark.us> <20070120200916.GB25307@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@sea.gmane.org Cc: Sunil Naidu , =?ISO-8859-1?Q?Ismail_D=F6nme?= =?ISO-8859-1?Q?z?= , linux-kernel@vger.kernel.org X-Gmane-NNTP-Posting-Host: mail.tmr.com User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061105 SeaMonkey/1.0.6 In-Reply-To: <20070120200916.GB25307@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Willy Tarreau wrote: > On Sat, Jan 20, 2007 at 02:56:20PM -0500, Stephen Clark wrote: >> Sunil Naidu wrote: >> >>> On 1/20/07, Willy Tarreau wrote: >>> >>> >>>> It is not expected to increase write performance, but it should help >>>> you do something else during that time, or also give more responsiveness >>>> to Ctrl-C. It is possible that you have fast and slow RAM, or that your >>>> video card uses shared memory which slows down some parts of memory >>>> which are not used anymore with those parameters. >>>> >>>> >>> I did test some SATA drives, am getting these value for 2.6.20-rc5:- >>> >>> [sukhoi@Typhoon ~]$ time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024 >>> 1024+0 records in >>> 1024+0 records out >>> 1073741824 bytes (1.1 GB) copied, 21.0962 seconds, 50.9 MB/s >>> >>> What can you suggest here w.r.t my RAM & disk? >>> >>> >>> >>>> Willy >>>> >>>> >>> 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/ >>> >>> >>> >> Hi, >> whitebook vbi s96f core 2 duo t5600 2gb hitachi ATA HTS721060G9AT00 >> using libata >> time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024 >> 1024+0 records in >> 1024+0 records out >> 1073741824 bytes (1.1 GB) copied, 10.0092 seconds, 107 MB/s >> >> real 0m10.196s >> user 0m0.004s >> sys 0m3.440s > > You have too much RAM, it's possible that writes did not complete before > the end of your measurement. Try this instead : > > $ time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024 | sync > I'm not sure that does what you think it does, the sync runs first, and data is still in the cache. Replace sync with "/bin/echo RAN" if you doubt me. What you want is this: sync; time bash -c "dd if=/dev/zero of=/tmp/1GB bs=1M count=1024; sync" which will actually time the write with the time command. -- Bill Davidsen "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot