Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754875AbZJTGgC (ORCPT ); Tue, 20 Oct 2009 02:36:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752269AbZJTGgA (ORCPT ); Tue, 20 Oct 2009 02:36:00 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:60881 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750962AbZJTGgA (ORCPT ); Tue, 20 Oct 2009 02:36:00 -0400 Date: Tue, 20 Oct 2009 08:35:55 +0200 From: Ingo Molnar To: Jiri Kosina Cc: Jeff Mahoney , Peter Zijlstra , Linux Kernel Mailing List , Tony Luck , Fenghua Yu , linux-ia64@vger.kernel.org Subject: Re: Commit 34d76c41 causes linker errors on ia64 with NR_CPUS=4096 Message-ID: <20091020063555.GJ8550@elte.hu> References: <4ADB967A.4080707@suse.com> <20091020061557.GE8550@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.19 (2009-01-05) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1229 Lines: 33 * Jiri Kosina wrote: > On Tue, 20 Oct 2009, Ingo Molnar wrote: > > > > Commit 34d76c41 introduced percpu array update_shares_data, size of which > > > being proportional to NR_CPUS. Unfortunately this blows up ia64 for large > > > NR_CPUS configuration, as ia64 allows only 64k for .percpu section. > > > > > > Fix this by allocating this array dynamically and keep only pointer to it > > > percpu. > > > > > > Signed-off-by: Jiri Kosina > > > --- > > > kernel/sched.c | 15 +++++++-------- > > > 1 files changed, 7 insertions(+), 8 deletions(-) > > > > Seems like an IA64 bug to me. > > IA64 guys actually use that as some kind of optimization for fast > access to the percpu data in their pagefault handler, as far as I > know. Still looks like a bug if it causes a breakage (linker error) on IA64, and if the 'fix' (i'd call it a workaround) causes a (small but nonzero) performance regression on other architectures. Ingo -- 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/