From patchwork Thu Aug 6 22:57:50 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 39706 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n76MxLok000974 for ; Thu, 6 Aug 2009 22:59:47 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753537AbZHFW7p (ORCPT ); Thu, 6 Aug 2009 18:59:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756491AbZHFW7p (ORCPT ); Thu, 6 Aug 2009 18:59:45 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:41776 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753537AbZHFW7o (ORCPT ); Thu, 6 Aug 2009 18:59:44 -0400 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [140.211.169.55]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id n76Mvp2u015696 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 6 Aug 2009 15:57:52 -0700 Received: from localhost.localdomain (localhost [127.0.0.1]) by imap1.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id n76Mvow2024171; Thu, 6 Aug 2009 15:57:50 -0700 Message-Id: <200908062257.n76Mvow2024171@imap1.linux-foundation.org> Subject: [patch 3/9] arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c: avoid cross-CPU interrupts by using smp_call_function_any() To: lenb@kernel.org Cc: linux-acpi@vger.kernel.org, akpm@linux-foundation.org, davej@redhat.com, efault@gmx.de, jaswinder@kernel.org, len.brown@intel.com, mingo@elte.hu, rusty@rustcorp.com.au, tglx@linutronix.de, venkatesh.pallipadi@intel.com, yakui.zhao@intel.com, yanmin_zhang@linux.intel.com From: akpm@linux-foundation.org Date: Thu, 06 Aug 2009 15:57:50 -0700 X-Spam-Status: No, hits=-3.511 required=5 tests=AWL, BAYES_00, OSDL_HEADER_SUBJECT_BRACKETED X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org From: Andrew Morton Presently acpi-cpufreq will perform the MSR read on the first CPU in the mask. That's inefficient if that CPU differs from the current CPU. Because we have to perform a cross-CPU call, but we could have run the rdmsr on the current CPU. So switch to using the new smp_call_function_any(), whcih will perform the call on the current CPU if that CPU is present in the mask (it is). Cc: "Zhang, Yanmin" Cc: Dave Jones Cc: Ingo Molnar Cc: Jaswinder Singh Rajput Cc: Len Brown Cc: Mike Galbraith Cc: Rusty Russell Cc: Thomas Gleixner Cc: Venkatesh Pallipadi Cc: Zhao Yakui Signed-off-by: Andrew Morton --- arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c~arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-cross-cpu-interrupts-by-using-smp_call_function_any arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c~arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-cross-cpu-interrupts-by-using-smp_call_function_any +++ a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c @@ -197,9 +197,11 @@ static void do_drv_write(void *_cmd) static void drv_read(struct drv_cmd *cmd) { + int err; cmd->val = 0; - smp_call_function_single(cpumask_any(cmd->mask), do_drv_read, cmd, 1); + err = smp_call_function_any(cmd->mask, do_drv_read, cmd, 1); + WARN_ON_ONCE(err); /* smp_call_function_any() was buggy? */ } static void drv_write(struct drv_cmd *cmd)