From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755080AbZAJWxO (ORCPT ); Sat, 10 Jan 2009 17:53:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751441AbZAJWw6 (ORCPT ); Sat, 10 Jan 2009 17:52:58 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:51506 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163AbZAJWw6 (ORCPT ); Sat, 10 Jan 2009 17:52:58 -0500 Date: Sat, 10 Jan 2009 23:52:29 +0100 From: Ingo Molnar To: Mike Travis , Andrew Morton Cc: Ingo Molnar , Rusty Russell , Yinghai Lu , Jack Steiner , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] kstat: modify kstat_irqs_legacy to be variable sized Message-ID: <20090110225229.GE17917@elte.hu> References: <20090110223818.459493000@polaris-admin.engr.sgi.com> <20090110223819.033438000@polaris-admin.engr.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090110223819.033438000@polaris-admin.engr.sgi.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: 1.0 X-ELTE-SpamLevel: s X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=1.0 required=5.9 tests=BAYES_50 autolearn=no SpamAssassin version=3.2.3 1.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.4934] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Travis wrote: > Impact: reduce memory usage. > > Allocate kstat_irqs_legacy based on nr_cpu_ids to deal with this > memory usage bump when NR_CPUS bumped from 128 to 4096: > > 8192 +253952 262144 +3100% kstat_irqs_legacy(.bss) > > This is only when CONFIG_SPARSE_IRQS=y. > > Signed-off-by: Mike Travis > --- > kernel/irq/handle.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > --- linux-2.6-for-ingo.orig/kernel/irq/handle.c > +++ linux-2.6-for-ingo/kernel/irq/handle.c > @@ -124,8 +124,7 @@ static struct irq_desc irq_desc_legacy[N > } > }; > > -/* FIXME: use bootmem alloc ...*/ > -static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS]; > +static unsigned int *kstat_irqs_legacy; > > int __init early_irq_init(void) > { > @@ -146,9 +145,13 @@ int __init early_irq_init(void) > /* allocate irq_desc_ptrs array based on nr_irqs */ > irq_desc_ptrs = alloc_bootmem(nr_irqs * sizeof(void *)); > > + /* allocate based on nr_cpu_ids */ > + kstat_irqs_legacy = alloc_bootmem(NR_IRQS_LEGACY * nr_cpu_ids * > + sizeof(int)); > + > for (i = 0; i < legacy_count; i++) { > desc[i].irq = i; > - desc[i].kstat_irqs = kstat_irqs_legacy[i]; > + desc[i].kstat_irqs = kstat_irqs_legacy + i * NR_IRQS_LEGACY; > lockdep_set_class(&desc[i].lock, &irq_desc_lock_class); > init_alloc_desc_masks(&desc[i], 0, true); > irq_desc_ptrs[i] = desc + i; btw., while at it - dont we want to upgrade this to a 'long' (in a separate commit)? Having more than 4 billion irqs after bootup is easily possible. Ingo