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SubjectRe: [patch 7/9] Adapt the time initialization code
On Thu, Feb 01, 2007 at 12:26:33PM +0100, Andi Kleen wrote:
> > +extern void time_initialize_cpu(void);
> Never put externs into .c files. Multiple occurrences.

Ok, will fix it, sorry.

> > +void time_initialize_cpu(void *info)
> > +{
> > + unsigned long flags;
> > + int cpu = smp_processor_id();
> Are you sure this can never preempt?

yes, preemption is explicitly disabled in start_secondary() that
calls this function.

> > + /* FIXME: what speed does the cpu really start at; I doubt cpu_khz is right at this point ??!!!
> It should be. It comes from measurements. Unless the CPU changes frequency
> behind the kernel's back, but there is nothing that can be done then.

Well, I'm not sure. I think the global variable cpu_khz is wrong
in the first place. This should be per-cpu, because each CPU can
have a different frequency, right?

And cpu_khz is adjusted in time_cpufreq_notifier() when whichever
CPU's frequency changes. To me it seems that it's a leftover from
the times when all CPUs in a system ran at the same speed. I
think it should be killed. I just did not want to make too many
unrelated changes in one patchset.

It doesn't matter that much in this case that it probably is
wrong (as the comment explains)...

Jiri Bohac <>

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