On Tue, 22 Apr 2008, Ingo Molnar wrote: > > > Or is it just a performance optimization? [...] > > yes and i gave in - Nick and Jens wants to do some crazy stuff and they > had the numbers. Here's the previous discussion: > > http://lkml.org/lkml/2008/2/27/125 No, the previous discussion was about single *queues* vs single *vectors*. I agree unconditionally with the decision to use a separate per-cpu queue from the shared queue (in fact, I would argue that the "mask" code might want to notice when the mask is just a single CPU, and turn a mask request into a targeted request). But I wonder why we want to then have two IPI target vectors, when it would appear to be perfectly fine and cheap to have just a single vector that can handle both the per-cpu case and the shared queue case (since the thing would tend to be one or the other, not both). A single vector is still pefectly fine, if 99% of all usage cases are the targeted-to-a-single-cpu thing, because the shared queue will basically be empty (and you can test that without even taking any locks). Linus -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
