Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751935AbZGJGyu (ORCPT ); Fri, 10 Jul 2009 02:54:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751023AbZGJGyn (ORCPT ); Fri, 10 Jul 2009 02:54:43 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:54419 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750939AbZGJGym (ORCPT ); Fri, 10 Jul 2009 02:54:42 -0400 Subject: Re: [patch v2] slub: add option to disable higher order debugging slabs From: Pekka Enberg To: David Rientjes Cc: Christoph Lameter , Larry Finger , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List , Johannes Berg In-Reply-To: References: <1246374095.8014.28.camel@penberg-laptop> <84144f020906302253n2424d4a5k3aaf124838a041df@mail.gmail.com> <84144f020907030023v2d09632bt13b6c25f96c0b803@mail.gmail.com> Date: Fri, 10 Jul 2009 09:54:39 +0300 Message-Id: <1247208879.19026.2.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit X-Mailer: Evolution 2.24.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1742 Lines: 37 On Tue, 7 Jul 2009, Christoph Lameter wrote: > > > + * Debugging flags that require metadata to be stored in the slab, up to > > > + * DEBUG_SIZE in size. > > > + */ > > > +#define DEBUG_SIZE_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER) > > > +#define DEBUG_SIZE (3 * sizeof(void *) + 2 * sizeof(struct track)) > > > > There is no need for DEBUG_SIZE since slub keeps both the size of the > > object kmem_cache->objsize and the size with the metadata kmem_cache->size > > > > If the order of both is different then the order would increase. On Thu, 2009-07-09 at 16:26 -0700, David Rientjes wrote: > Without DEBUG_SIZE_FLAGS, the only way to determine what flags have > increased the size is in calculate_sizes() and then disable them by > default if slub_debug=O is specified. calculate_sizes() is used by > the `store', `poison', and `red_zone' callbacks, so the admin still has > the ability to enable these options even though slub_debug=O was used. > > So we can either mask off the size-increasing debug bits when the cache is > created in kmem_cache_flags() like I did, or we can move the logic to > calculate_sizes() with an added formal to determine whether this is from > kmem_cache_open() or one of the attribute callbacks. > > I think my solution is the cleanest and provides a single entity, > DEBUG_SIZE_FLAGS, which specifies the flags that slub_debug=O clears if > the minimum order increases. Yup, agreed. I applied the patch, thanks everyone! Pekka -- 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/