Re: [PATCH] Extend mwait idle to optimize away CAL and RESinterrupts to an idle CPU -v1

From: Ingo Molnar
Date: Thu Feb 23 2012 - 02:50:48 EST



* Venkatesh Pallipadi <venki@xxxxxxxxxx> wrote:

> * Do we need some accounting for these wakeups exported for powertop?

If then tracepoints.

> * We can also eliminate TS_POLLING flag in favor of this. But, that will have
> a lot more touchpoints and better done as a standlone change.

Should most definitely be done for this series to be acceptble -
as a preparatory patch in the series, with the feature at the
end of the series.

> +DECLARE_PER_CPU(atomic_t *, idle_task_ti_flags);

That's ugly, we should access the idle task's ti flags directly.

To have efficient percpu access to the idle threads another
clean-up is needed: we should turn idle_thread_array into a
full-structure PER_CPU area.

For that we need a small variant of fork_idle(), which does not
dup the init thread - pretty trivial.

fork_idle() should also make sure it does not schedule the child
thread: thus we'd also be able to further simplify smpboot.c and
get rid of all that extremely ugly 'struct create_idle'
gymnastics in smpboot.c.

Thanks,

Ingo
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