Messages in this thread | | | Date | Tue, 22 Apr 2008 21:26:01 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 2/11] x86: convert to generic helpers for IPI function calls |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > 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).
ok. In which case the reschedule vector could be consolidated into that as well (it's just a special single-CPU call). Then there would be no new vector allocations needed at all, just the renaming of RESCHEDULE_VECTOR to something more generic.
Ingo
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