From 4a28395d72a956f2dad24e343d06bc08c9afb89a Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 21 Dec 2009 16:19:58 -0800 Subject: [PATCH] arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c: avoid cross-CPU interrupts by using smp_call_function_any() 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(), which 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 Signed-off-by: Len Brown --- arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c index f28decf8dde3..1b1920fa7c80 100644 --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c @@ -190,9 +190,11 @@ 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) -- 2.20.1