From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 9 Sep 2001 12:54:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 9 Sep 2001 12:54:48 -0400 Received: from colorfullife.com ([216.156.138.34]:268 "EHLO colorfullife.com") by vger.kernel.org with ESMTP id ; Sun, 9 Sep 2001 12:54:40 -0400 Message-ID: <3B9B9EE4.4D40AAB6@colorfullife.com> Date: Sun, 09 Sep 2001 18:55:00 +0200 From: Manfred Spraul X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.8-ac1 i686) X-Accept-Language: en, de MIME-Version: 1.0 To: Alan Cox CC: Linus Torvalds , Andrea Arcangeli , linux-kernel@vger.kernel.org Subject: Re: Purpose of the mm/slab.c changes In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Alan Cox wrote: > > > > doesn't matter which free page is used first/last. > > > > You're full of crap. > > LIFO is obviously superior due to cache re-use. > > Interersting question however. On SMP without sufficient per CPU slab caches > is tht still the case ? Correct. SMP was perfect LIFO even without Andrea's changes. I thought Andrea tried to reduce the fragmentation, therefore I wrote "free is free". But even for cache re-use his changes are not a big change: The main fifo/lifo ordering on UP is mandated by the defragmentation property of the slab allocator. Afaics there is exactly one case where my code is not lifo and Andrea's is: kmem_cache_free frees the last object in slab, each slab contains more than one object, and there are no further partial slabs. In all other cases Andrea just adds list_del();list_add() instead of changes to the firstnotfull pointer. full->partial is/was lifo, partial->partial doesn't change the lists at all partial->empty was fifo, is now lifo_if_no_partial_slab_exists -- Manfred