On Thu, 17 Jul 2014, Pranith Kumar wrote: > I can mention that IPI is preferable. What is that you don't want mentioned? > atomic_t?
Definitely not as an example. atomic_t in per cpu areas is self contradicting. The per cpu area is exclusively for that processor whereas an atomic_t is supposed to be accessed from multiple processors. > > Remote percpu updates are extremely rare events. If the cpu is idle/asleep > > then usually no updates are needed because no activity is occurring on > > that cpu. > > > > Yes, -usually- that is the case. But we are talking about the extreme rare > event > where we need to update some remote CPU`s per-cpu data without waking it up > from > sleep/idle. How do you suggest we handle this? I don't think suggesting not to > use per-cpu areas because of this is a good idea, since we lose a lot of > performance in the most common cases. If you modify a percpu area then that is usually done because that cpu needs to take some action. An IPI is fine. Otherwise yes I would suggest not use a percpu area but a separate data structure for synchronization. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
