Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753560AbXIPRv1 (ORCPT ); Sun, 16 Sep 2007 13:51:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752137AbXIPRvS (ORCPT ); Sun, 16 Sep 2007 13:51:18 -0400 Received: from lazybastard.de ([212.112.238.170]:37280 "EHLO longford.lazybastard.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751718AbXIPRvR (ORCPT ); Sun, 16 Sep 2007 13:51:17 -0400 Date: Sun, 16 Sep 2007 19:46:58 +0200 From: =?utf-8?B?SsO2cm4=?= Engel To: Andrea Arcangeli Cc: Goswin von Brederlow , Andrew Morton , Joern Engel , Nick Piggin , Christoph Lameter , torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Mel Gorman , William Lee Irwin III , David Chinner , Jens Axboe , Badari Pulavarty , Maxim Levitsky , Fengguang Wu , swin wang , totty.lu@gmail.com, hugh@veritas.com Subject: Re: [00/41] Large Blocksize Support V7 (adds memmap support) Message-ID: <20070916174657.GA2393@lazybastard.org> References: <20070911060349.993975297@sgi.com> <200709110452.20363.nickpiggin@yahoo.com.au> <20070911121225.GE13132@lazybastard.org> <20070915014449.4f9cdb51.akpm@linux-foundation.org> <87ir6c3z2l.fsf@informatik.uni-tuebingen.de> <20070915155100.GA21861@v2.random> <87tzpvy9cb.fsf@informatik.uni-tuebingen.de> <20070915223032.GA6708@v2.random> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20070915223032.GA6708@v2.random> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1493 Lines: 32 On Sun, 16 September 2007 00:30:32 +0200, Andrea Arcangeli wrote: > > Movable? I rather assume all slab allocations aren't movable. Then > slab defrag can try to tackle on users like dcache and inodes. Keep in > mind that with the exception of updatedb, those inodes/dentries will > be pinned and you won't move them, which is why I prefer to consider > them not movable too... since there's no guarantee they are. I have been toying with the idea of having seperate caches for pinned and movable dentries. Downside of such a patch would be the number of memcpy() operations when moving dentries from one cache to the other. Upside is that a fair amount of slab cache can be made movable. memcpy() is still faster than reading an object from disk. Most likely the current reaction to such a patch would be to shoot it down due to overhead, so I didn't pursue it. All I have is an old patch to seperate never-cached from possibly-cached dentries. It will increase the odds of freeing a slab, but provide no guarantee. But the point here is: dentries/inodes can be made movable if there are clear advantages to it. Maybe they should? Jörn -- Joern's library part 2: http://www.art.net/~hopkins/Don/unix-haters/tirix/embarrassing-memo.html - 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/