[dpdk-dev] [PATCH v2 0/2] Vhost: unitfy receive paths

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi,

This second version fixes the feature bit check in
rxvq_is_mergeable(), and remove "mergeable" from rx funcs
names. No difference is seen in the benchmarks

This series is preliminary work to ease the integration of
packed ring layout support. But even without packed ring
layout, the result is positive.

First patch unify both paths, and second one is a small
optimization to avoid copying batch_copy_nb_elems VQ field
to/from the stack.

With the series applied, I get modest performance gain for
both mergeable and non-mergeable casesi (, and the gain of
about 300 LoC is non negligible maintenance-wise.

Rx-mrg=off benchmarks:

+------------+-------+-------------+-------------+----------+
|    Run     |  PVP  | Guest->Host | Host->Guest | Loopback |
+------------+-------+-------------+-------------+----------+
| v18.05-rc5 | 14.47 |       16.64 |       17.57 |    13.15 |
| + series   | 14.87 |       16.86 |       17.70 |    13.30 |
+------------+-------+-------------+-------------+----------+

Rx-mrg=on benchmarks:

+------------+------+-------------+-------------+----------+
|    Run     | PVP  | Guest->Host | Host->Guest | Loopback |
+------------+------+-------------+-------------+----------+
| v18.05-rc5 | 9.38 |       13.78 |       16.70 |    12.79 |
| + series   | 9.38 |       13.80 |       17.49 |    13.36 |
+------------+------+-------------+-------------+----------+

Note: Even without my series, the guest->host benchmark with
mergeable buffers enabled looks suspicious as it should in
theory be alsmost identical as when Rx mergeable buffers are
disabled. To be investigated...

Maxime Coquelin (2):
  vhost: unify Rx mergeable and non-mergeable paths
  vhost: improve batched copies performance

 lib/librte_vhost/virtio_net.c | 376 +++++-------------------------------------
 1 file changed, 37 insertions(+), 339 deletions(-)

-- 
2.14.3