From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 13 Oct 2004 17:23:53 +1000 From: Nathan Scott Subject: Re: Page cache write performance issue Message-ID: <20041013172352.B4917536@wobbly.melbourne.sgi.com> References: <20041013054452.GB1618@frodo> <20041012231945.2aff9a00.akpm@osdl.org> <20041013063955.GA2079@frodo> <20041013000206.680132ad.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041013000206.680132ad.akpm@osdl.org>; from akpm@osdl.org on Wed, Oct 13, 2004 at 12:02:06AM -0700 Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: piggin@cyberone.com.au, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@oss.sgi.com List-ID: On Wed, Oct 13, 2004 at 12:02:06AM -0700, Andrew Morton wrote: > > Well something else if fishy: how can you possibly achieve only 4MB/sec? These are 1K writes too remember, so it feels a bit like we write 'em out one at a time, sync (though no O_SYNC, or fsync, or such involved here). This is on an i686, so 4K pages, and using 4K filesystem blocksizes (both xfs and ext2). And now that you mention, yes, this is multiple times below the direct IO numbers too (which on this box are ~30MB/sec for direct blkdev writes, IIRC, & XFS has similar numbers). > Using floppy disks or something? Heh, uh, no. (and no, not "pencils" either ;) > Does the same happen on ext2? Yes. > It's exactly a 500MB write on a 1000MB machine, yes? Thats correct. No slab/page/.. debug options enabled either - its the same .config that was performing ~10x better on 2.6.8. I also verified that it wasn't any of the XFS changes either (they wouldn't have affected ext2 anyway, of course) - the same XFS code backported to 2.6.8 performs fine also. cheers. -- Nathan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org