Re: apmd and other archs

On Fri, 24 Nov 2000, Benjamin Herrenschmidt wrote:

We can "fix" that by either having the PMU driver on core99 continuously
send those infos via /dev/pmu without explicit request. It may also be
interesting to replace this by a kernel thread. That would allow more
flexibility in communicating with userland (things like signaling
processes that asked for it to be notified of a sleep request, etc...).

Could the recently added keventd thread be used for this? I don't like the
idea of adding kernel threads just for one thing. One kernel thread for
all relatively slow operations which may need a process context is
reasonable however.

One other issue we have with sleep is that we need to prevent the kernel
to do a bunch of thigns while going to sleep. scheduling from within the
sleep ioctl is dangerous, but will happen occasionally, especially when
sleeping & waking up the IDE layer.

I beleive it should be possible to hack the scheduler so that only our
sleep thread gets scheduled at all (disabling scheduling on the main CPU
and freezing other CPUs in sleep loops) during the sleep & wakeup process.

Any better ideas ?

No, I thought the deep sleep modes were only for laptops which are not SMP
unless I missed some recent Apple announcement ;-). Do SMP G4 truly
require complex power management ?

BTW: I dislike any idea of playing with the scheduler.

	Gabriel.


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