profiling the resume path

[Jens Axboe]

On Sun, Sep 02 2007, David Woodhouse wrote:
> On Sun, 2007-09-02 at 04:10 -0400, Marcelo Tosatti wrote:
> > Note: ohci_pci_resume does msleep 20. 
> 
> Hm. It's just waiting for the hardware to settle, right? Do the resume
> functions for the devices themselves actually have to wait until this is
> complete, before they can do anything?
> 
> It really sounds like we need to decouple suspend/resume of individual
> hardware devices from the full system suspend. It should be almost
> completely asynchronous. Why can't I start running userspace after
> resume, before I've reinitialised the USB thermometer which is plugged
> in? Why don't we just block access to that particular device until it's
> complete (and take that device off-line to save power even when the full
> system isn't suspended).

It's similar to what libata now does. You may be stuck waiting for an IO
after resume is done, but you have your graphics and everything back
quickly. It's the sane thing to do, imho...

-- 
Jens Axboe