[PATCH RFC v2 0/2] vhost: ring format independence

From: Michael S. Tsirkin
Date: Sat Oct 12 2019 - 15:18:55 EST

This adds infrastructure required for supporting
multiple ring formats.

The idea is as follows: we convert descriptors to an
independent format first, and process that converting to
iov later.

The point is that we have a tight loop that fetches
descriptors, which is good for cache utilization.
This will also allow all kind of batching tricks -
e.g. it seems possible to keep SMAP disabled while
we are fetching multiple descriptors.

This seems to perform exactly the same as the original
code already based on a microbenchmark.
More testing would be very much appreciated.

Biggest TODO before this first step is ready to go in is to
batch indirect descriptors as well.

Integrating into vhost-net is basically
s/vhost_get_vq_desc/vhost_get_vq_desc_batch/ -
or add a module parameter like I did in the test module.

Changes from v1:
- typo fixes

Michael S. Tsirkin (2):
vhost: option to fetch descriptors through an independent struct
vhost: batching fetches

drivers/vhost/test.c | 19 ++-
drivers/vhost/vhost.c | 333 +++++++++++++++++++++++++++++++++++++++++-
drivers/vhost/vhost.h | 20 ++-
3 files changed, 365 insertions(+), 7 deletions(-)