On Fri, May 28, 2010 at 5:12 PM, Igor Stoppa <igor.stoppa@xxxxxxxxx> wrote: > ext Brian Swetland wrote: >> How is it flawed? Serious question. > > I would avoid repeating all the good arguments given so far, but to make it > short: > > * I believe runtime PM is a much better starting point (at least for the > type of HW targeted at mobile devices) because it mimics an always-on system > toward userspace, which requires less disruption in the way apps are > designed I agree. If I understand correctly, if we have a perfect user-space that only does work when strictly needed and trying to do it in bursts, then we would be reaching the lowest power state, and there would be no need for suspend. The problem is that Android's user-space is pretty far from that, so they said "let's segregate user-space and go to lower power mode anyway". If that's true, then this problem can be fixed in user-space, and in fact, it already is on N900. Good behaving applications are asynchronous, use g_timeout_add_seconds() to align bursts of work at the same second intervals, and don't do polls directly, but use GLib's mainloop. Same as in GNOME desktop. It seems there are other methods to align multiple processes for longer periods of time, but that code is closed and I can't find much information. > * QoS is closer to the apps pov: fps if it is a media player or a game, > transfer speed if it is a file manager, bandwidth if it is a network app, > etc > The app is required to express its opinion by using a format that it > understands better and is less system dependent. > Actually the kernel should only be concerned with 2 parameters at most for > any given operation: latency and bandwidth/throughput I think this information can be obtained dynamically while the application is running, and perhaps the limits can be stored. It would be pretty difficult for the applications to give this kind of information because there are so many variables. For example, an media player can tell you: this clip has 24 fps, but if the user is moving the time slider, the fps would increase and drop very rapidly, and how much depends at least on the container format and type of seek. A game or a telephony app could tell you "I need real-time priority" but so much as giving the details of latency and bandwidth? I find that very unlikely. Cheers. -- Felipe Contreras -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
