Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754687AbZCGFfS (ORCPT ); Sat, 7 Mar 2009 00:35:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752143AbZCGFes (ORCPT ); Sat, 7 Mar 2009 00:34:48 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:55045 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752402AbZCGFer (ORCPT ); Sat, 7 Mar 2009 00:34:47 -0500 Date: Fri, 6 Mar 2009 21:34:44 -0800 From: "Paul E. McKenney" To: Christoph Lameter Cc: Lai Jiangshan , Andrew Morton , Pekka Enberg , Nick Piggin , Manfred Spraul , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm 3/6] slub: introduce __kfree_rcu Message-ID: <20090307053444.GB10625@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <49AD343E.6010903@cn.fujitsu.com> <49AF28C4.1000300@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1138 Lines: 27 On Thu, Mar 05, 2009 at 09:39:03AM -0500, Christoph Lameter wrote: > On Thu, 5 Mar 2009, Lai Jiangshan wrote: > > > The first parameter of __kfree_rcu() is unused in slab,slub,slqb. > > (I used it before, for CONFIG_SLUB_DEBUG=y ...etc. But I found > > these debugging code is needless) > > > > Object sizes of the memory objects in slob's kmalloc-slab are various. > > We hardly calculate the start address of the object from the rcu address. > > But you can start with the descriptor at the beginning of the page and > scan until you find the object. Another approach would be to keep a per-page bitmap of the objects that are awaiting a grace period. Not sure whether or not it is worthwhile, but it does reduce the per-object overhead to two bits (one for the objects awaiting the current grace period, the other for objects that will await the next grace period). Thanx, Paul -- 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/