On Wed, Apr 07, 2010 at 12:37:03PM -0700, Roland Dreier wrote:
> > No, there is no mmap. Like this:
> >
> > u64 my_counter = 0;
> >
> > ibv_set_mmu_counter(verbs, &my_counter);
> > [..]
> > while (my_counter != last_my_counter) {
> > last_my_counter = my_counter;
> > ibv_get_mmu_notifications(verbs, ...); // <- I am a memory barrier
> as well
> > }
> >
> > The kernel 'syscall' ibv_set_mmu_counter would bind the given verbs to
> > the 8 byte counter you specified without having to the mmap thing. As
> > I understand it this is what perfevents does.
>
> I was trying to look at how perf events handles this, and AFAICT it
> looks like kernel/perf_event.c just supports mmap(). Can you expand on
> what you meant here?
>
> (I was trying to figure out how one would handle the case where
> userspace gives us a counter in highmem -- doing kmap_atomic() seems to
> be to only option but then I'm not sure if I want to deal with that...)
I think I was mistaken here, disregard..
Jason
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