Re: [PATCH 1/3] dynticks - implement no idle hz for x86

[Srivatsa Vaddagiri <vatsa@in.ibm.com>]

On Wed, Sep 07, 2005 at 09:42:24AM -0700, Nish Aravamudan wrote:
> Hrm, got dropped from the Cc... :) Yes, the dynamic-tick generic
> infrastructure being proposed, with the idle CPU mask and the
> set_all_cpus_idle() tick_source hook, would allow exactly this in
> arch-specific code.

I think Bill is referring to the "resume" interface i.e an
unset_all_cpus_idle() interface, which is missing (set/unset
probably are not good prefixes maybe?). I feel we can
add one.

> Is there a generic location where the all-idle state is entered?

Should be from the place where the last cpu is set in the bitmap
and bitmap is found equal to cpu_online_map.

> Currently, I think we can do it via the generic reprogram() routine
> checking the mask and then calling set_all_cpus_idle(), if
> appropriate, after reprogramming the last idle CPU.

So are you saying that setting of the CPU in the bitmap will be done
inside reprogram_timer routine? If we consider that reprogram_timer can 
directly point to a routine in a interrupt source file (like apic.c/timer_pit.c)
I dont think that it is the right place to set bits in the nohz_cpu_mask.
It can be done by the callee of reprogram_timer itself.

-- 


Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017
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