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SubjectRe: [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U0

* Karim Yaghmour <> wrote:

> Ingo Molnar wrote:
> >
> I notice:
> + local_irq_save(flags);
> + ____trace(&__get_cpu_var(trace), eip, parent_eip);
> + local_irq_restore(flags);
> Why not use the lockless logging available in relayfs, you'll avoid
> the interrupt disabling altogether since, umm ... it's lockless.

i just added something ad-hoc. I wanted it to be accurate across
interrupt entries. I have not looked at the relayfs locking but how does
it solve that? Also, cli/sti makes it obviously SMP-safe and is pretty
cheap on all x86 CPUs. (Also, i didnt want to use preempt_disable/enable
because the tracer interacts with that code quite heavily.)

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