Re: [PATCH] NMI: fix NMI period is not correct when cpu frequencychanges issue.

[Andrew Morton]

On Tue, 16 Apr 2013 03:45:15 +0000 "Pan, Zhenjie" <zhenjie.pan@xxxxxxxxx> wrote:

> > Overall the patch looks desirable, but it increases the kernel size by several
> > hundred bytes when CONFIG_CPU_FREQ=n.  It should produce no code in
> > this case!  Take a look at the magic in register_hotcpu_notifier(), the way in
> > which it causes all the code to be removed by the compiler in the
> > CONFIG_HOTPLUG_CPU=n case.  That trick can be used here.
> 
> I have checked if CONFIG_CPU_FREQ=n, cpufreq_register_notifier() will be a blank function.
> So I think it will not increases the kernel size.

I tested it.  The patch adds ~350 bytes of dead code.

This is partly an infrastructural problem: unlike
register_hotcpu_notifier(), the cpufreq notifier code lacks the
infrastructure with which we can prevent this problem.

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