Re: Ummunotify: progress at last!

[Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>]

 > I would prefer to do this by adding a new verbs call that returns a fd
 > directly. Ie use ib_uverbs_alloc_event_file and act like
 > ibv_create_comp_channel.
 > 
 > The main reason for the new FD is so it can be polled on..

Agree, we don't want a new device node I don't think -- too hard to
associate an fd you get from a separate open() with a uverbs context.

 > You can also avoid the mmap scheme by doing what perf events does,
 > pass in a pointer from userspace and have the kernel pin that page it
 > is on.

I wonder, is that a win?  I guess you don't even have to pin it, just do
copy_to_user() to update the counter, but mmap doesn't seem so bad.

I'll have to look at the perf code.
-- 
Roland Dreier  <rolandd-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
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