On Wed, 4 Jul 2007, Matthew Garrett wrote: > On Wed, Jul 04, 2007 at 10:38:47AM -0400, Alan Stern wrote: > > > Okay, I agree that (1) can be handled without too much effort. But > > doing it adds an extra test to _every_ driver's I/O pathway. Freezing > > userspace does not incur all this additional overhead. > > For runtime PM to work it's already necessary to have a test in that > path to check if the device is suspended. I can't see how this adds any > overhead to the common case. Actually it isn't necessary to have a test to check if the device is suspended. We simply call the autoresume routine; if the device isn't suspended that routine doesn't have to do anything. I agree that that the extra test (for system-wide suspend underway) is needed only if the autoresume fails, which isn't part of the main pathway. So it doesn't add runtime overhead -- but handling it does add code overhead. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
