Re: [PATCH RFC 0/4] Scheduler idle notifiers and users
From: Ingo Molnar
Date: Sat Feb 11 2012 - 09:45:56 EST
* Saravana Kannan <skannan@xxxxxxxxxxxxxx> wrote:
> When you say accommodate all hardware, does it mean we will
> keep around CPUfreq and allow attempts at improving it? Or we
> will completely move to scheduler based CPU freq scaling, but
> won't try to force atomicity? Say, may be queue up a
> notification to a CPU driver to scale up the frequency as soon
> as it can?
I don't think we should (or even could) force atomicity - we
adapt to whatever the hardware can do.
But the design should be directed at systems where frequency
changes can be done in a reasonably fast manner. That is what he
future is - any change we initiate today takes years to reach
actual products/systems.
> IMHO, I think the problem with CPUfreq and its dynamic
> governors today is that they do a timer based sampling of the
> CPU load instead of getting some hints from the scheduler when
> the scheduler knows that the load average is quite high.
Yes - that is one of the "frequency changes are slow"
assumptions - which is wrong.
Thanks,
Ingo
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