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authorAndrew Morton <akpm@linux-foundation.org>2009-12-21 16:19:58 -0800
committerLen Brown <len.brown@intel.com>2009-12-22 15:03:57 -0500
commit4a28395d72a956f2dad24e343d06bc08c9afb89a (patch)
tree37418b244175d017061bb4aef257c379dce859f4 /arch
parent55639353a0035052d9ea6cfe4dde0ac7fcbb2c9f (diff)
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" <yanmin_zhang@linux.intel.com> Cc: Dave Jones <davej@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jaswinder Singh Rajput <jaswinder@kernel.org> Cc: Len Brown <len.brown@intel.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Zhao Yakui <yakui.zhao@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index f28decf8dde..1b1920fa7c8 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)