From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756783AbZDKG0s (ORCPT ); Sat, 11 Apr 2009 02:26:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756142AbZDKG0Q (ORCPT ); Sat, 11 Apr 2009 02:26:16 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:46385 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755763AbZDKG0P (ORCPT ); Sat, 11 Apr 2009 02:26:15 -0400 Message-Id: <200904110617.n3B6HHi4026499@imap1.linux-foundation.org> Subject: [patch for 2.6.30 1/2] arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c: avoid using work_on_cpu() To: lenb@kernel.org Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, davej@redhat.com, efault@gmx.de, 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: Fri, 10 Apr 2009 23:17:17 -0700 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrew Morton Atttempting to rid us of the problematic work_on_cpu(). Just use smp_call_fuction_single() here. This repairs a 10% sysbench(oltp)+mysql regression which Mike reported, due to commit 6b44003e5ca66a3fffeb5bc90f40ada2c4340896 Author: Andrew Morton Date: Thu Apr 9 09:50:37 2009 -0600 work_on_cpu(): rewrite it to create a kernel thread on demand It seems that the kernel calls these acpi-cpufreq functions at a quite high frequency. Cc: Rusty Russell Cc: Ingo Molnar Cc: Venkatesh Pallipadi Cc: Len Brown Cc: Zhao Yakui Cc: Dave Jones Cc: Thomas Gleixner Tested-by: Mike Galbraith Cc: "Zhang, Yanmin" Signed-off-by: Andrew Morton --- arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 25 ++++++++----------- 1 file changed, 11 insertions(+), 14 deletions(-) diff -puN arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c~arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-using-work_on_cpu 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-using-work_on_cpu +++ a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c @@ -153,7 +153,8 @@ struct drv_cmd { u32 val; }; -static long do_drv_read(void *_cmd) +/* Called via smp_call_function_single(), on the target CPU */ +static void do_drv_read(void *_cmd) { struct drv_cmd *cmd = _cmd; u32 h; @@ -170,10 +171,10 @@ static long do_drv_read(void *_cmd) default: break; } - return 0; } -static long do_drv_write(void *_cmd) +/* Called via smp_call_function_single(), on the target CPU */ +static void do_drv_write(void *_cmd) { struct drv_cmd *cmd = _cmd; u32 lo, hi; @@ -192,23 +193,21 @@ static long do_drv_write(void *_cmd) default: break; } - return 0; } static void drv_read(struct drv_cmd *cmd) { cmd->val = 0; - work_on_cpu(cpumask_any(cmd->mask), do_drv_read, cmd); + smp_call_function_single(cpumask_any(cmd->mask), do_drv_read, cmd, 1); } static void drv_write(struct drv_cmd *cmd) { - unsigned int i; + unsigned int cpu; - for_each_cpu(i, cmd->mask) { - work_on_cpu(i, do_drv_write, cmd); - } + for_each_cpu(cpu, cmd->mask) + smp_call_function_single(cpu, do_drv_write, cmd, 1); } static u32 get_cur_val(const struct cpumask *mask) @@ -252,15 +251,13 @@ struct perf_pair { } aperf, mperf; }; - -static long read_measured_perf_ctrs(void *_cur) +/* Called via smp_call_function_single(), on the target CPU */ +static void read_measured_perf_ctrs(void *_cur) { struct perf_pair *cur = _cur; rdmsr(MSR_IA32_APERF, cur->aperf.split.lo, cur->aperf.split.hi); rdmsr(MSR_IA32_MPERF, cur->mperf.split.lo, cur->mperf.split.hi); - - return 0; } /* @@ -283,7 +280,7 @@ static unsigned int get_measured_perf(st unsigned int perf_percent; unsigned int retval; - if (!work_on_cpu(cpu, read_measured_perf_ctrs, &readin)) + if (smp_call_function_single(cpu, read_measured_perf_ctrs, &cur, 1)) return 0; cur.aperf.whole = readin.aperf.whole - _