Re: [PATCH 1/8] PM: Add suspend block api.

Daniel Walker
2010-05-07T18:00:55Z

On Fri, 2010-05-07 at 18:51 +0100, Matthew Garrett wrote:
> On Fri, May 07, 2010 at 10:40:43AM -0700, Daniel Walker wrote:
> > On Fri, 2010-05-07 at 18:36 +0100, Matthew Garrett wrote:
> > > If your wakeup latencies are sufficiently low and you have fine-grained
> > > enough control over your hardware then suspend in idle is a reasonable
> > > thing to do - but if you have a userspace app that's spinning then
> > > that doesn't solve the issue.
> >
> > If there's a userspace app spinning then you don't go idle (or that's my
> > assumption anyway). You mean like repeatedly blocking and unblocking
> > right?
>
> Right, that's the problem. idle-based suspend works fine if your
> applications let the system go idle, but if your applications are
> anything other than absolutely perfect in this respect then you consume
> significant power even if the device is sitting unused in someone's
> pocket.

True .. I'd wonder how an OMAP based devices deal with that issue, since
they would have that exact problem. According to what Tony is telling
us. Actually a bogus userspace can do a lot more than just consume power
you could hang the system too.

Daniel