From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932409AbWGLD4A (ORCPT ); Tue, 11 Jul 2006 23:56:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932407AbWGLD4A (ORCPT ); Tue, 11 Jul 2006 23:56:00 -0400 Received: from ms-smtp-03.nyroc.rr.com ([24.24.2.57]:37618 "EHLO ms-smtp-03.nyroc.rr.com") by vger.kernel.org with ESMTP id S932406AbWGLDz7 (ORCPT ); Tue, 11 Jul 2006 23:55:59 -0400 Subject: Re: 2.6.17-mm6 From: Steven Rostedt To: Andrew Morton Cc: Keith Mannthey , linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner , "Eric W. Biederman" In-Reply-To: <20060705172545.815872b6.akpm@osdl.org> References: <20060703030355.420c7155.akpm@osdl.org> <20060705155037.7228aa48.akpm@osdl.org> <20060705164457.60e6dbc2.akpm@osdl.org> <20060705164820.379a69ba.akpm@osdl.org> <20060705172545.815872b6.akpm@osdl.org> Content-Type: text/plain Date: Tue, 11 Jul 2006 23:55:21 -0400 Message-Id: <1152676521.8309.9.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2006-07-05 at 17:25 -0700, Andrew Morton wrote: > On Wed, 5 Jul 2006 17:05:49 -0700 > "Keith Mannthey" wrote: > > > On 7/5/06, Andrew Morton wrote: > > > On Wed, 5 Jul 2006 16:44:57 -0700 > > > Andrew Morton wrote: > > > > > > > I guess a medium-term fix would be to add a boot parameter to override > > > > PERCPU_ENOUGH_ROOM - it's hard to justify increasing it permanently just > > > > for the benefit of the tiny minority of kernels which are hand-built with > > > > lots of drivers in vmlinux. > > [snip] > > So you've been hit by the expansion of NR_IRQS which bloats kernel_stat > which gobbles per-cpu data. > > In 2.6.17 NR_IRQS is 244. In -mm (due to the x86_64 genirq conversion) > NR_IRQS became (256 + 32 * NR_CPUS). Hence the kstat "array" became > two-dimensional. It's now O(NR_CPUS^2). > > I don't know what's a sane max for NR_CPUS on x86_64, but that'll sure be a > showstopper if the ia64 guys try the same trick. > > I guess one fix would be to de-percpuify kernel_stat.irqs[]. Or > dynamically allocate it with alloc_percpu(). And people wondered why I'm fighting for the robust per_cpu variables. http://marc.theaimsgroup.com/?l=linux-kernel&m=114785997413023&w=2 Yes there's still problems with this. But if I ever get some more time to work on it, I would like to solve those issues. Having that PERCPU_ENOUGH_ROOM laying around in the kernel is just disgusting ;) Sorry, for the noise, I have another 2288 more LKML emails to read :) -- Steve