From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932992AbXGLOpI (ORCPT ); Thu, 12 Jul 2007 10:45:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754013AbXGLOo6 (ORCPT ); Thu, 12 Jul 2007 10:44:58 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:45061 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752863AbXGLOo5 (ORCPT ); Thu, 12 Jul 2007 10:44:57 -0400 Date: Fri, 13 Jul 2007 00:44:49 +1000 From: David Chinner To: Andrea Arcangeli Cc: David Chinner , linux-kernel@vger.kernel.org Subject: Re: RFC: CONFIG_PAGE_SHIFT (aka software PAGE_SIZE) Message-ID: <20070712144449.GZ31489@sgi.com> References: <20070706222651.GG5777@v2.random> <20070708232031.GF12413810@sgi.com> <20070710101148.GJ1482@v2.random> <20070712001256.GI31489@sgi.com> <20070712111436.GG28613@v2.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070712111436.GG28613@v2.random> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 12, 2007 at 01:14:36PM +0200, Andrea Arcangeli wrote: > On Thu, Jul 12, 2007 at 10:12:56AM +1000, David Chinner wrote: > > I need really large filesystems that contain both small and large files to > > work more efficiently on small boxes where we can't throw endless amounts of > > RAM and CPUs at the problem. Hence things like 64k page size are just not an > > option because of the wastage that it entails. > > I didn't know you were allocating 4k pages for the small files and 64k > for the large ones in the same fs. That sounds quite a bit > overkill. We already have rudimentary multi-block size support via the per-inode extent size hint, but we still cache based on the filesystem block size ('coz we can't increase it). All I want is to be able to change the index granularity in the page cache with minimal impact and everything in XFS falls almost straight out in a pretty optimal manner. > I still think you should run those systems with PAGE_SIZE 64k even if > it'll waste you more memory on the small files. That's crap. Just because a machine has lots of memory does not make it OK to waste lots of memory. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group