From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751116AbWAYLAd (ORCPT ); Wed, 25 Jan 2006 06:00:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751117AbWAYLAd (ORCPT ); Wed, 25 Jan 2006 06:00:33 -0500 Received: from cantor2.suse.de ([195.135.220.15]:37355 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1751116AbWAYLAc (ORCPT ); Wed, 25 Jan 2006 06:00:32 -0500 Date: Wed, 25 Jan 2006 12:00:31 +0100 From: Nick Piggin To: Pekka Enberg Cc: Nick Piggin , Linux Kernel Mailing List , Linux Memory Management List Subject: Re: [RFC] non-refcounted pages, application to slab? Message-ID: <20060125110031.GC30421@wotan.suse.de> References: <20060125093909.GE32653@wotan.suse.de> <84144f020601250230s2d5da5d9jf11f754f184d495b@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <84144f020601250230s2d5da5d9jf11f754f184d495b@mail.gmail.com> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 25, 2006 at 12:30:03PM +0200, Pekka Enberg wrote: > Hi Nick, > > On 1/25/06, Nick Piggin wrote: > > This is probably not worthwhile for most cases, but slab did strike me > > as a potential candidate (however the complication here is that some > > code I think uses the refcount of underlying pages of slab allocations > > eg nommu code). So it is not a complete patch, but I wonder if anyone > > thinks the savings might be worth the complexity? > > > > Is there any particular code that is really heavy on slab allocations? > > That isn't mostly handled by the slab's internal freelists? > > I certainly hope not. For heavy users, the slab allocator should grow > caches enough to satisfy most allocations from the them. Also, I think I figured this would usually be the case. > we want to keep the reference counting for slab pages so that we can > use kmalloc'd memory in the block layer. > Does that happen now? Where is it needed (nbd or something I guess?) Nick