[PATCH -next 0/6] epoll: some miscellaneous optimizations

[Davidlohr Bueso]

Hi,

The following are some incremental optimizations on some of the epoll
core. Each patch has the details, but together, the series is seen
to shave off measurable cycles on a number of systems and workloads.

For example, on a 40-core IB, a pipetest as well as parallel epoll_wait()
benchmark show around a 20-30% increase in raw operations per second when
the box is fully occupied (incremental thread counts), and up to 15%
performance improvement with lower counts.

Passes ltp epoll related testcases. Please consider for v4.21/5.0.

Thanks!

Davidlohr Bueso (6):
  fs/epoll: remove max_nests argument from ep_call_nested()
  fs/epoll: simplify ep_send_events_proc() ready-list loop
  fs/epoll: drop ovflist branch prediction
  fs/epoll: robustify ep->mtx held checks
  fs/epoll: reduce the scope of wq lock in epoll_wait()
  fs/epoll: avoid barrier after an epoll_wait(2) timeout

 fs/eventpoll.c | 206 ++++++++++++++++++++++++++++++---------------------------
 1 file changed, 108 insertions(+), 98 deletions(-)

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2.16.4