[dpdk-dev] [PATCH v4 0/3] vhost: make virtqueue cache-friendly

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

As done for Virtio PMD, this series improves cache utilization
of the vhost_virtqueue struct by removing unused field,
make the live-migration cache dynamically allocated at
live-migration setup time and by moving fields
around so that hot fields are on the first cachelines.

With this series, The struct vhost_virtqueue size goes
from 832B (13 cachelines) down to 320B (5 cachelines).

With this series and the virtio one, I measure a gain
of up to 8% in IO loop micro-benchmark with packed
ring, and 5% with split ring.

I don't have a setup at hand to run PVP testing, but
it might be interresting to get the numbers as I
suspect the cache pressure is higher in this test as
in real use-cases.

Changes in v4:
==============
- Fix missing changes to boolean (Chenbo)

Changes in v3:
==============
- Don't check pointer validity before freeing (David)
- Don't use deprecated rte_smp_wmb() (David, Checkpatch)
- Handle booleans properly (David)
- Prevent VQ size field overflow (David)
- Fix typo and indent (David)

Changes in v2:
==============
- Add log_cache freeing in free_vq (Chenbo)

Maxime Coquelin (3):
  vhost: remove unused Vhost virtqueue field
  vhost: move dirty logging cache out of the virtqueue
  vhost: optimize vhost virtqueue struct

 lib/librte_vhost/vhost.c      | 21 +++++++++----
 lib/librte_vhost/vhost.h      | 56 +++++++++++++++++------------------
 lib/librte_vhost/vhost_user.c | 44 +++++++++++++++++++--------
 lib/librte_vhost/virtio_net.c | 12 ++++----
 4 files changed, 82 insertions(+), 51 deletions(-)

-- 
2.30.2