Re: [GIT PULL] oprofile fixes for v2.6.40

From: Ingo Molnar
Date: Mon May 30 2011 - 06:10:09 EST



* Robert Richter <robert.richter@xxxxxxx> wrote:

> > But i really do not see how this can work. get_eilvt() twiddles
> > the APIC LVT of this current CPU. Does IBS only activate on a
> > single CPU? How will this LVT entry be cleared on deinit?
>
> This is done on the current cpu to get the offset which is then
> used on all cpus of the system. The actually per-core setup for ibs
> is in op_amd_setup_ctrs(). Deinit is in op_amd_cpu_shutdown().

The way IBS is set up is not very obvious and atypical of existing
preempt_*() patters. Might be worth adding a comment to the
preempt_disable(), to unconfuse unsuspecting readers who are
wondering about its oddness?

Anyway, i suspected that it was correctly working code so i pulled it
and pushed it to Linus, it should all be in 3.0-rc1.

Thanks,

Ingo
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