git: if_vtnet - Don't drop vtnet_slz in some of the virtqueue_notify() calls.

[Imre Vadasz]

commit 36ad0f356d159f9a99f74f2fd4559443ef9af7f9
Author: Imre Vadász <imre at vdsz.com>
Date:   Sun Mar 25 21:59:43 2018 +0200

    if_vtnet - Don't drop vtnet_slz in some of the virtqueue_notify() calls.
    
    * There are several cases where the vtnet_slz serializer is dropped around
      virtqueue_notify() calls, with the hope that this allows other cores to
      run if_vtnet code in parallel.
    
    * In vtnet_exec_ctrl_cmd(), it shouldn't make a significant performance
      difference, and avoids some theoretical race possibilities.
    
    * In the vtnet_init_rx_vq initialization code, it also is irrelevant for
      performance, and only complicates things.
    
    * In the vtnet_rxeof() and vtnet_start() cases it might actually be relevant
      for performance, so we keep those for now. When changing the driver to
      use the MULTI_SERIALIZERS MODE, the serializer dropping can also be
      removed in those two cases.

Summary of changes:
 sys/dev/virtual/virtio/net/if_vtnet.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/36ad0f356d159f9a99f74f2fd4559443ef9af7f9


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