Re: [PATCH 1/3] dynticks - implement no idle hz for x86
From: Bill Davidsen
Date: Wed Sep 07 2005 - 11:10:58 EST
Srivatsa Vaddagiri wrote:
On Sun, Sep 04, 2005 at 10:48:13PM -0700, Nishanth Aravamudan wrote:
Admittedly, I don't think SMP ARM has been around all that long? Maybe
the existing code just has not been extended.
Yeah, maybe ARM never cared for SMP. But we do care :)
I'm not sure on this. It's going to be NULL for other architectures, or
end up being called by the reprogram() call for the last CPU to go idle,
right (presuming there isn't a separate TOD source, like in x86). I
think it is better to be in the reprogram() interface.
Non-x86 could have it set to NULL, in which case it doesn't get called.
(I know the current code does not take care of this situation).
But having an explicit 'all_cpus_idle' interface may be good, since
Tony talked of idling some devices when all CPUs are idle. So it
probably has non-x86/PIT uses too.
If this is intended to reduce power, and it originally came from that
root, then this is the time to put in a hook for transitions to<=>from
the all-idle state. Various arch may have things other than the PIT
which should (or at least can) be stopped, and which need to be restarted.
--
-bill davidsen (davidsen@xxxxxxx)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
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