Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761071AbXIMBtw (ORCPT ); Wed, 12 Sep 2007 21:49:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754921AbXIMBtn (ORCPT ); Wed, 12 Sep 2007 21:49:43 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:49395 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750814AbXIMBtm (ORCPT ); Wed, 12 Sep 2007 21:49:42 -0400 Date: Thu, 13 Sep 2007 11:49:05 +1000 From: David Chinner To: Nick Piggin Cc: David Chinner , Mel Gorman , Christoph Lameter , andrea@suse.de, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig , William Lee Irwin III , Jens Axboe , Badari Pulavarty , Maxim Levitsky , Fengguang Wu , swin wang , totty.lu@gmail.com, hugh@veritas.com, joern@lazybastard.org Subject: Re: [00/41] Large Blocksize Support V7 (adds memmap support) Message-ID: <20070913014905.GV995458@sgi.com> References: <20070911060349.993975297@sgi.com> <200709111600.18756.nickpiggin@yahoo.com.au> <20070912014917.GJ995458@sgi.com> <200709120127.33832.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200709120127.33832.nickpiggin@yahoo.com.au> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1118 Lines: 30 On Wed, Sep 12, 2007 at 01:27:33AM +1000, Nick Piggin wrote: > > IOWs, we already play these vmap harm-minimisation games in the places > > where we can, but still the overhead is high and something we'd prefer > > to be able to avoid. > > I don't think you've looked nearly far enough with all this low hanging > fruit. Ok, so we need to hack the vm to optimise it further. When it comes to TLB flush code and optimising that sort of stuff, I'm out of my depth. > I just gave 4 things which combined might easily reduce xfs vmap overhead > by several orders of magnitude, all without changing much code at all. Patches would be greatly appreciately. You obviously understand this vm code much better than I do, so if it's easy to fix by adding some generic vmap cache thingy, please do. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - 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/