Hi Tejun, On 26 November 2012 22:45, Tejun Heo <tj@xxxxxxxxxx> wrote: > On Tue, Nov 06, 2012 at 04:08:45PM +0530, Viresh Kumar wrote: > I'm pretty skeptical about this. queue_work() w/o explicit CPU > assignment has always guaranteed that the work item will be executed > on the same CPU. I don't think there are too many users depending on > that but am not sure at all that there are none. I asked you last > time that you would at the very least need to audit most users but it > doesn't seem like there has been any effort there. My bad. I completely missed/forgot that comment from your earlier mails. Will do it. > That said, if the obtained benefit is big enough, sure, we can > definitely change the behavior, which isn't all that great to begin > with, and try to shake out the bugs quicky by e.g. forcing all work > items to execute on different CPUs, but you're presenting a few > percent of work items being migrated to a different CPU from an > already active CPU, which doesn't seem like such a big benefit to me > even if the migration target CPU is somewhat more efficient. How much > powersaving are we talking about? Hmm.. I actually implemented the problem discussed here: (I know you have seen this earlier :) ) http://www.linuxplumbersconf.org/2012/wp-content/uploads/2012/08/lpc2012-sched-timer-workqueue.pdf Specifically slides: 12 & 19. I haven't done much power calculations with it and have tested it more from functionality point of view. @Vincent: Can you add some comments here? -- viresh -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
