Re: [patch] x86_64: fix sched_clock()

[Andi Kleen]

On Fri, May 25, 2007 at 11:03:15AM +0200, Andi Kleen wrote:
> > This?    I sent it to you earlier this week:
> 
> Sorry haven't processed those yet.
> 
> Ah. The correct fix here is to clear the tsc flag in boot_cpu_data
> when the option is set. Will do that.

Hmm I double checked this now; tsc_disable indeed clears
X86_FEATURE_TSC in identify_cpu and that should be always
called before anything sched_clock related runs on a CPU.

Also the only possibly faulting division is protected
by a cpu_has_tsc which even checks boot_cpu_data. this means
even if the resync frequency code was called for
some reason before the identify_cpu of a AP it should
still work. For the BP this definitely cannot happen.

I also tried it with qemu myself (both one and two cpus) and it worked

Rusty, was this really on a standard kernel? Was it with multiple
CPUs? 

-Andi
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