On Wed, 9 Jun 2010 11:40:27 +0200 "Rafael J. Wysocki" <rjw@xxxxxxx> wrote: > On Wednesday 09 June 2010, Felipe Contreras wrote: > > On Wed, Jun 9, 2010 at 6:46 AM, Linus Torvalds > > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > On Tue, 8 Jun 2010, david@xxxxxxx wrote: > > >> > > >> having suspend blockers inside the kernel adds significant complexity, it's > > >> worth it only if the complexity buys you enough. In this case the question is > > >> if the suspend blockers would extend the sleep time enough more to matter. As > > >> per my other e-mail, this is an area with rapidly diminishing returns as the > > >> sleep times get longer. > > > > > > Well, the counter-argument that nobody seems to have brought up is that > > > suspend blockers exist, are real code, and end up being shipped in a lot > > > of machines. > > > > > > That's a _big_ argument in favour of them. Certainly much bigger than > > > arguing against them based on some complexity-arguments for an alternative > > > that hasn't seen any testing at all. > > > > > > IOW, I would seriously hope that this discussion was more about real code > > > that _exists_ and does what people need. It seems to have degenerated into > > > something else. > > > > > > Because in the end, "code talks, bullshit walks". People can complain and > > > suggest alternatives all they want, but you can't just argue. At some > > > point you need to show the code that actually solves the problem. > > > > That's assuming there is an actual problem, which according to all the > > embedded people except android, there is not. > > Yes, there is, but they've decided to ignore it. > > > And if there is indeed such a problem (probably not big), it might be > > solved properly by the time suspend blockers are merged, or few > > releases after. > > Not quite. Have you followed all of the discussion, actually? > > > Whatever the solution (or workaround) is, it would be nice if it could > > be used by more than just android people, and it would also be nice to > > do it without introducing user-space API that *nobody* likes and might > > be quickly deprecated. > > I agree with Linus and I don't have that much of a problem with the API that > people seem to have. In fact the much-hated user space API is just a char > device driver with 3 ioctls (that can be extended in future if need be) and > the kernel API is acceptable to me. I think there is a little bit more to it than that. It seems there is a new ioctl for input/event devices to say "Any events queued here should be treated as wake-up events". There may be similar additions to other devices, but I know of no details. I wonder if we can get a complete statement of changes to the user-space API... > Yes, there is some overlap between it > and PM QoS, but IMhO that overlap may be reduced over time (eg. by > using PM QoS requirements to implement suspend blockers). > > To me, the question boils down to whether or not we're able to persuade the > Android people to use any other approach (eg. by demonstrating that something > else is actually better), because even if we invent a brilliant new approach, > but Android ends up using its old one anyway, the net result will be as though > we haven't done anything useful. Yes. There is no point unless we can meet somewhere in the middle. I think that would have to include a full suspend that freezes all processes. Solutions which reject that - while quite clever - would require too much change to Android user-space to be acceptable. NeilBrown > > Rafael -- 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
