Re: [patch for 2.6.30 2/2]arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c: avoid cross-CPUinterrupts

From: Dave Jones
Date: Sat Apr 11 2009 - 20:08:59 EST


On Fri, Apr 10, 2009 at 11:17:18PM -0700, Andrew Morton wrote:
> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>
> In drv_read(), check to see whether we can run the rdmsr() on the current
> CPU. If so, do that. So smp_call_function_single() can avoid the IPI.

Wouldn't it be a better to make smp_call_function_single do this check
itself, so all callers benefit from this optimisation?

*looks*

Wait, won't this already be caught by this code in smp_call_function_single() ?

286 this_cpu = get_cpu();
...
291 if (cpu == this_cpu) {
292 local_irq_save(flags);
293 func(info);
294 local_irq_restore(flags);
295 } else {



Dave

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