To better match bdev modules like nvme, complete requests
for the bdev/null driver asynchronously. This will be
done by allocating IO channels that register a poller
and keep a TAILQ of bdev IO to be completed next time
the poller runs.
This is actually more efficient as well, since completing
I/O in submit_request context defers the completion using
an event. A benchmark of bdevperf with split running on
top of null module shows this patch increases throughput
20%.
Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I8c664234660c249fd8ec8d9244eed33502d4103e
Reviewed-on: https://review.gerrithub.io/392528
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
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