Re: [linux-pm] [PATCH 0/8] Suspend block api (version 6)

From: Alan Stern
Date: Fri May 14 2010 - 22:35:46 EST


On Fri, 14 May 2010, Rafael J. Wysocki wrote:

> > > How do you handle situations where the CPU is currently idle but an
> > > event (such as I/O completion) is expected to occur in the near future?
> > > You don't want to power-off and reboot then, do you?
> >
> > The idle code looks at next_timer_interrupt() value, then if the
> > next timer event if far enough ahead, the system powers down and
> > wakes to the timer interrupt. It also wakes to device interrupts.
>
> For the record, waking to interrupts doesn't work on quite some systems
> (like ACPI-based PCs for one example).

Ironically, it appears that ACPI-based PCs are in a position to benefit
more from opportunistic suspend and suspend blockers than are embedded
systems -- and yet they are being proposed for use on cell phones
rather than on desktops.

Alan Stern

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