On Mon, Oct 08, 2012 at 11:39:19PM -0700, Kent Overstreet wrote:

It simplifies a lot of stuff if the ringbuffer is contiguously mapped
into kernel space, and we can delete a lot of code - in particular, this
is useful for converting read_events() to cmpxchg.

1) I'm concerned that Our Favourite Database Benchmarkers will see an
effect of having more TLB pressure from that mapping.  kmap_atomic()
should be cheaper.  We'll need to measure the difference.

2) I'm not at all convinced that the current ring semantics are safe
with cmpxchg(), more in the next patch.

- z