Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755045AbZFKOjp (ORCPT ); Thu, 11 Jun 2009 10:39:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752638AbZFKOji (ORCPT ); Thu, 11 Jun 2009 10:39:38 -0400 Received: from fmailhost02.isp.att.net ([204.127.217.102]:43672 "EHLO fmailhost02.isp.att.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751989AbZFKOjh (ORCPT ); Thu, 11 Jun 2009 10:39:37 -0400 X-Originating-IP: [65.28.94.183] Message-ID: <4A311727.40403@lwfinger.net> Date: Thu, 11 Jun 2009 09:39:35 -0500 From: Larry Finger User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Pekka Enberg CC: Christoph Lameter , linux-kernel@vger.kernel.org, mel@csn.ul.ie Subject: Re: [PATCH 2/2] SLUB: Disable debugging if it increases the minimum page order References: <1244728824.17483.51.camel@penberg-laptop> In-Reply-To: <1244728824.17483.51.camel@penberg-laptop> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2496 Lines: 64 Pekka Enberg wrote: > Hi Christoph, > > On Thu, 2009-06-11 at 09:43 -0400, Christoph Lameter wrote: >> We have had that with SLAB. NO! This leads to the situation that some >> slabs have debug on and some have not. You just do not know which. > > I do see your point but surely we don't want to use order 1 allocations > in the fall-back case for kmalloc-4096? Couldn't we just add a printk > saying that debug was disabled for the cache? After all, my patch is > much better than what SLAB does. > > On Thu, 2009-06-11 at 09:43 -0400, Christoph Lameter wrote: >> Note that CONFIG_SLUB_DEBUG only enables the code to debug a slab. It does >> not enable debugging for each slab. CONFIG_SLUB_DEBUG_ON does that. > > True. Larry, do you have CONFIG_SLUB_DEBUG_ON enabled or are you passing > SLUB debugging options to the kernel? It is enabled in the kernel. My SLUB options in .config are: finger@larrylap:~> grep SLUB .config CONFIG_SLUB_DEBUG=y CONFIG_SLUB=y CONFIG_SLUB_DEBUG_ON=y # CONFIG_SLUB_STATS is not set Would having STATS enabled help? For a bug that hits infrequently, determining that it is fixed is difficult. That said, my system has been up about 22.5 hours during which I have tried to force the failure. I see the fragmentation of memory vary widely as shown below: finger@larrylap:~> date ; cat /proc/buddyinfo Wed Jun 10 20:15:34 CDT 2009 Node 0, zone DMA 4 3 5 2 4 1 2 0 1 0 0 Node 0, zone DMA32 5920 11678 2245 369 117 21 2 1 0 0 0 finger@larrylap:~> date ; cat /proc/buddyinfo Wed Jun 10 23:32:39 CDT 2009 Node 0, zone DMA 4 3 5 2 4 1 2 0 1 0 0 Node 0, zone DMA32 2605 4140 3804 7 0 1 1 1 0 0 0 finger@larrylap:~> date ; cat /proc/buddyinfo Thu Jun 11 09:28:06 CDT 2009 Node 0, zone DMA 4 3 5 2 4 1 2 0 1 0 0 Node 0, zone DMA32 2231 429 2726 54 1 0 1 1 0 0 0 finger@larrylap:~> cat /proc/uptime 80678.11 78.54 The latest value of the number of O(1) fragments is about as low as I have seen. Larry -- 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/