From: Andrew Morton Subject: Re: partially uptodate page reads Date: Sun, 27 Jul 2008 23:51:24 -0700 Message-ID: <20080727235124.5b04fd8b.akpm@linux-foundation.org> References: <200807250117.11331.nickpiggin@yahoo.com.au> <20080724175913.GA32117@infradead.org> <20080724120841.81c72be9.akpm@linux-foundation.org> <6.0.0.20.2.20080728115511.045088a8@172.19.0.2> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , Nick Piggin , jack@ucw.cz, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com To: Hisashi Hifumi Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:42449 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751578AbYG1Gvl (ORCPT ); Mon, 28 Jul 2008 02:51:41 -0400 In-Reply-To: <6.0.0.20.2.20080728115511.045088a8@172.19.0.2> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 28 Jul 2008 13:34:12 +0900 Hisashi Hifumi wrote: > Hi > > >> > > >> > Are there significant numbers of people using block size < page size in > >> > situations where performance is important and significantly improved by > >> > this patch? Can you give any performance numbers to illustrate perhaps? > >> > >> With XFS lots of people use 4k blocksize filesystems on ia64 systems > >> with 16k pages, so an optimization like this would be useful. > > > >As Nick says, we really should have some measurement results which > >confirm this theory. Maybe we did do some but they didn't find theor > >way into the changelog. > > > >I've put the patch on hold until this confirmation data is available. > > > > I've got some performance number. > I wrote a benchmark program and got result number with this program. > This benchmark do: > 1, mount and open a test file. > 2, create a 512MB file. > 3, close a file and umount. > 4, mount and again open a test file. > 5, pwrite randomly 300000 times on a test file. offset is aligned by IO size(1024bytes). > 6, measure time of preading randomly 100000 times on a test file. > > The result was: > 2.6.26 > 330 sec > > 2.6.26-patched > 226 sec > > Arch:i386 > Filesystem:ext3 > Blocksize:1024 bytes > Memory: 1GB > > On ext3/4, a file is written through buffer/block. So random read/write mixed workloads > or random read after random write workloads are optimized with this patch under > pagesize != blocksize environment. This test result showed this. OK, thanks. Those are pretty nice numbers for what is probably a fairly common workload.