From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Jaswinder Singh Rajput <jaswinder@xxxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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
@@ -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)
_
--
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