From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030304AbWFUVA3 (ORCPT ); Wed, 21 Jun 2006 17:00:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030287AbWFUVA2 (ORCPT ); Wed, 21 Jun 2006 17:00:28 -0400 Received: from rhlx01.fht-esslingen.de ([129.143.116.10]:52967 "EHLO rhlx01.fht-esslingen.de") by vger.kernel.org with ESMTP id S1030281AbWFUVAY (ORCPT ); Wed, 21 Jun 2006 17:00:24 -0400 Date: Wed, 21 Jun 2006 23:00:23 +0200 From: Andreas Mohr To: Andrew Morton Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: [PATCH -mm 4/6] cpu_relax(): smpboot.c Message-ID: <20060621210023.GD22516@rhlx01.fht-esslingen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i X-Priority: none Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Add cpu_relax() to various smpboot.c init loops. Kept mb() since it's said to be required in some postings. Tested on 2.6.17-mm1. Signed-off-by: Andreas Mohr diff -urN linux-2.6.17-mm1.orig/arch/i386/kernel/smpboot.c linux-2.6.17-mm1.my/arch/i386/kernel/smpboot.c --- linux-2.6.17-mm1.orig/arch/i386/kernel/smpboot.c 2006-06-21 14:28:15.000000000 +0200 +++ linux-2.6.17-mm1.my/arch/i386/kernel/smpboot.c 2006-06-21 14:43:24.000000000 +0200 @@ -251,8 +251,10 @@ /* * all APs synchronize but they loop on '== num_cpus' */ - while (atomic_read(&tsc_count_start) != num_booting_cpus()-1) + while (atomic_read(&tsc_count_start) != num_booting_cpus()-1) { + cpu_relax(); mb(); + } atomic_set(&tsc_count_stop, 0); wmb(); /* @@ -270,8 +272,10 @@ /* * Wait for all APs to leave the synchronization point: */ - while (atomic_read(&tsc_count_stop) != num_booting_cpus()-1) + while (atomic_read(&tsc_count_stop) != num_booting_cpus()-1) { + cpu_relax(); mb(); + } atomic_set(&tsc_count_start, 0); wmb(); atomic_inc(&tsc_count_stop); @@ -328,19 +332,27 @@ * this gets called, so we first wait for the BP to * finish SMP initialization: */ - while (!atomic_read(&tsc_start_flag)) mb(); + while (!atomic_read(&tsc_start_flag)) { + cpu_relax(); + mb(); + } for (i = 0; i < NR_LOOPS; i++) { atomic_inc(&tsc_count_start); - while (atomic_read(&tsc_count_start) != num_booting_cpus()) + while (atomic_read(&tsc_count_start) != num_booting_cpus()) { + cpu_relax(); mb(); + } rdtscll(tsc_values[smp_processor_id()]); if (i == NR_LOOPS-1) write_tsc(0, 0); atomic_inc(&tsc_count_stop); - while (atomic_read(&tsc_count_stop) != num_booting_cpus()) mb(); + while (atomic_read(&tsc_count_stop) != num_booting_cpus()) { + cpu_relax(); + mb(); + } } } #undef NR_LOOPS @@ -1446,8 +1458,10 @@ per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; /* Unleash the CPU! */ cpu_set(cpu, smp_commenced_mask); - while (!cpu_isset(cpu, cpu_online_map)) + while (!cpu_isset(cpu, cpu_online_map)) { + cpu_relax(); mb(); + } return 0; }