From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: ext4_fallocate Date: Tue, 26 Jun 2012 15:57:09 -0400 Message-ID: <4FEA1415.8040809@redhat.com> References: <4FE8086F.4070506@zoho.com> <20120625085159.GA18931@gmail.com> <20120625191744.GB9688@thunk.org> <4FE9B57F.4030704@redhat.com> <4FE9F9F4.7010804@zoho.com> <4FEA0DD1.8080403@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Fredrick , Ric Wheeler , "Theodore Ts'o" , linux-ext4@vger.kernel.org, Andreas Dilger , wenqing.lz@taobao.com To: Ric Wheeler Return-path: Received: from mx1.redhat.com ([209.132.183.28]:6180 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751960Ab2FZT5T (ORCPT ); Tue, 26 Jun 2012 15:57:19 -0400 In-Reply-To: <4FEA0DD1.8080403@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 6/26/12 3:30 PM, Ric Wheeler wrote: > Thanks! Eric is also running some tests to evaluate the impact of various techniques :) > > ric Yup forgive me for interjecting actual numbers into the discussion ;) I tried running this fio recipe on v3.3, which I think does a decent job of emulating the situation (fallocate 1G, do random 1M writes into it, with fsyncs after each): [test] filename=testfile rw=randwrite size=1g filesize=1g bs=1024k ioengine=sync fallocate=1 fsync=1 Stock ext4 (3 tests w/ file remove & cache drop in between): WRITE: io=1024.0MB, aggrb=16322KB/s, minb=16713KB/s, maxb=16713KB/s, mint=64243msec, maxt=64243msec WRITE: io=1024.0MB, aggrb=16249KB/s, minb=16639KB/s, maxb=16639KB/s, mint=64528msec, maxt=64528msec WRITE: io=1024.0MB, aggrb=16370KB/s, minb=16763KB/s, maxb=16763KB/s, mint=64052msec, maxt=64052msec With the patch which exposes other users' data: WRITE: io=1024.0MB, aggrb=17840KB/s, minb=18268KB/s, maxb=18268KB/s, mint=58776msec, maxt=58776msec WRITE: io=1024.0MB, aggrb=17841KB/s, minb=18269KB/s, maxb=18269KB/s, mint=58773msec, maxt=58773msec WRITE: io=1024.0MB, aggrb=17828KB/s, minb=18255KB/s, maxb=18255KB/s, mint=58816msec, maxt=58816msec so about 10% faster than without. XFS, FWIW: WRITE: io=1024.0MB, aggrb=24008KB/s, minb=24584KB/s, maxb=24584KB/s, mint=43675msec, maxt=43675msec WRITE: io=1024.0MB, aggrb=24069KB/s, minb=24647KB/s, maxb=24647KB/s, mint=43564msec, maxt=43564msec WRITE: io=1024.0MB, aggrb=24054KB/s, minb=24632KB/s, maxb=24632KB/s, mint=43591msec, maxt=43591msec which is 35% faster than ext4 with the risky patch. Haven't yet tried overwrites or done any tracing or profiling, but I think the fio recipe is a decent demonstrator, I'll try the overwrites etc in a bit when I get a moment. -Eric