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

Matthew Garrett
2010-06-01T13:51:22Z

On Mon, May 31, 2010 at 04:21:09PM -0500, James Bottomley wrote:

> You're the one mentioning x86, not me. I already explained that some
> MSM hardware (the G1 for example) has lower power consumption in S3
> (which I'm using as an ACPI shorthand for suspend to ram) than any
> suspend from idle C state. The fact that current x86 hardware has the
> same problem may be true, but it's not entirely relevant.

As long as you can set a wakeup timer, an S state is just a C state with
side effects. The significant one is that entering an S state stops the
process scheduler and any in-kernel timers. I don't think Google care at
all about whether suspend is entered through an explicit transition or
something hooked into cpuidle - the relevant issue is that they want to
be able to express a set of constraints that lets them control whether
or not the scheduler keeps on scheduling, and which doesn't let them
lose wakeup events in the process.

--
Matthew Garrett | mjg59@srcf.ucam.org