From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932095Ab2JPR6K (ORCPT ); Tue, 16 Oct 2012 13:58:10 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:48470 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755016Ab2JPR6I (ORCPT ); Tue, 16 Oct 2012 13:58:08 -0400 Date: Tue, 16 Oct 2012 09:32:11 -0700 From: "Paul E. McKenney" To: "Srivatsa S. Bhat" Cc: peterz@infradead.org, acme@ghostprotocols.net, mingo@kernel.org, tglx@linutronix.de, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [RESEND PATCH 2/2] perf, cpu hotplug: Use cached value of smp_processor_id() Message-ID: <20121016163211.GB2385@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20121016075809.3572.47848.stgit@srivatsabhat.in.ibm.com> <20121016075817.3572.76733.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121016075817.3572.76733.stgit@srivatsabhat.in.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12101617-5406-0000-0000-0000012BB623 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 16, 2012 at 01:28:17PM +0530, Srivatsa S. Bhat wrote: > The perf_cpu_notifier() macro invokes smp_processor_id() multiple > times. Optimize it by using a local variable. > > Signed-off-by: Srivatsa S. Bhat Reviewed-by: Paul E. McKenney > --- > > include/linux/perf_event.h | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 0647805..6bfb2faa 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -803,15 +803,16 @@ static inline void perf_event_task_tick(void) { } > do { \ > static struct notifier_block fn##_nb __cpuinitdata = \ > { .notifier_call = fn, .priority = CPU_PRI_PERF }; \ > + unsigned long cpu = smp_processor_id(); \ > unsigned long flags; \ > fn(&fn##_nb, (unsigned long)CPU_UP_PREPARE, \ > - (void *)(unsigned long)smp_processor_id()); \ > + (void *)(unsigned long)cpu); \ > local_irq_save(flags); \ > fn(&fn##_nb, (unsigned long)CPU_STARTING, \ > - (void *)(unsigned long)smp_processor_id()); \ > + (void *)(unsigned long)cpu); \ > local_irq_restore(flags); \ > fn(&fn##_nb, (unsigned long)CPU_ONLINE, \ > - (void *)(unsigned long)smp_processor_id()); \ > + (void *)(unsigned long)cpu); \ > register_cpu_notifier(&fn##_nb); \ > } while (0) > >