[PATCH V3 0/6] vhost code cleanup and minor enhancement

[Jason Wang <jasowang@redhat.com>]

This series tries to unify and simplify vhost codes especially for
zerocopy. With this series, 5% - 10% improvement for per cpu throughput were
seen during netperf guest sending test.

Plase review.

Changes from V2:
- Typo fixes and code style fix
- Add performance gain in the commit log of patch 2/6
- Retest the update the result in patch 6/6

Changes from V1:
- Fix the zerocopy enabling check by changing the check of upend_idx != done_idx
  to (upend_idx + 1) % UIO_MAXIOV == done_idx.
- Switch to use put_user() in __vhost_add_used_n() if there's only one used
- Keep the max pending check based on Michael's suggestion.

Jason Wang (6):
  vhost_net: make vhost_zerocopy_signal_used() return void
  vhost_net: use vhost_add_used_and_signal_n() in
    vhost_zerocopy_signal_used()
  vhost: switch to use vhost_add_used_n()
  vhost_net: determine whether or not to use zerocopy at one time
  vhost_net: poll vhost queue after marking DMA is done
  vhost_net: correctly limit the max pending buffers

 drivers/vhost/net.c   |   92 ++++++++++++++++++++++--------------------------
 drivers/vhost/vhost.c |   54 ++++++----------------------
 2 files changed, 54 insertions(+), 92 deletions(-)