On Thu, 3 Jun 2010, Linus Torvalds wrote: > > so I'd like to see the opportunistc suspend thing think about CPU > offlining Side note: one reason for me being somewhat interested in the CPU offlining is that I think the Android kind of opportunistic suspend is _not_ likely something I'd like to see on a desktop. But an the "opportunistic CPU offliner"? That might _well_ be useful even outside of any other suspend activity. If the system is idle (or almost idle) for long times, I would heartily recommend actively shutting down unused cores. Some CPU's are hopefully smart enough to not even need that kind of software management, but I suspect even the really smart ones might be able to take advantage of the kernel saying: "I'm shutting you down, you don't have to worry about latency AT ALL, because I'm keeping another CPU active to do any real work". I'd also be interested to see if it could even improve single-thread performance if we end up doing the whole SMP->UP "lock" prefix rewriting when the system is idle enough that we'd be better off running just a single core. I dunno - just throwing that out there. Anyway, the only reason I think this is related is literally because I think that if we know there is only a single CPU active, I think the actual "real" opportunistic suspend is easier. Suddenly you don't have to worry about what happens on other run-queues etc, and whether another CPU is just about to create a suspend block etc. So I think they tie together, although it's mostly tangential. And as mentioned, I think a opportunistic CPU suspend part is more relevant outside of Android, and thus perhaps more widely interesting. Linus -- 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
