Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932545AbWEXB7r (ORCPT ); Tue, 23 May 2006 21:59:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932546AbWEXB7r (ORCPT ); Tue, 23 May 2006 21:59:47 -0400 Received: from vbn.0050556.lodgenet.net ([216.142.194.234]:62169 "EHLO vbn.0050556.lodgenet.net") by vger.kernel.org with ESMTP id S932545AbWEXB7q (ORCPT ); Tue, 23 May 2006 21:59:46 -0400 Subject: Re: [PATCH] Per-superblock unused dentry LRU lists. From: Arjan van de Ven To: David Chinner Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org In-Reply-To: <20060524012412.GB7412499@melbourne.sgi.com> References: <20060524012412.GB7412499@melbourne.sgi.com> Content-Type: text/plain Date: Wed, 24 May 2006 03:59:40 +0200 Message-Id: <1148435980.3049.11.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1386 Lines: 35 On Wed, 2006-05-24 at 11:24 +1000, David Chinner wrote: > http://marc.theaimsgroup.com/?l=linux-kernel&m=114491661527656&w=2 > > shrink_dcache_sb() becomes a severe bottleneck when the unused dentry > list becomes long and mounts and unmounts occur frequently on the > machine. how does a per SB list deal with umounts that occur frequently? I suppose it means destroying just your list... > I've attempted to make reclaim fair by keeping track of the last superblock > we pruned, and starting from the next on in the list each time. how fair is this in the light of a non-equal sizes? say you have a 4Gb fs and a 1Tb list. Will your approach result in trying to prune 1000 from the 4Gb, then 1000 from the 1Tb, then 1000 from the 4Gb etc ? while that is fair in absolute terms, in relative terms it's highly not fair to the small filesystem.... (I'm not sure there is ONE right answer here, well maybe by scaling the count to the per fs count rather than to the total...) this makes me wonder btw if we can do a per superblock slab for these dentries, that may decrease fragmentation of slabs in combination with your patch.... - 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/