[PATCH RFC v3 0/4] vhost: ring format independence

From: Michael S. Tsirkin
Date: Sun Oct 13 2019 - 04:08:22 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.
Lightly tested.
More testing would be very much appreciated.

To use new code:
echo 1 > /sys/module/vhost_test/parameters/newcode
echo 1 > /sys/module/vhost_net/parameters/newcode

Changes from v2:
- fixed indirect descriptor batching

Changes from v1:
- typo fixes

Michael S. Tsirkin (4):
vhost: option to fetch descriptors through an independent struct
vhost/test: add an option to test new code
vhost: batching fetches
vhost/net: add an option to test new code

drivers/vhost/net.c | 32 +++-
drivers/vhost/test.c | 19 ++-
drivers/vhost/vhost.c | 340 +++++++++++++++++++++++++++++++++++++++++-
drivers/vhost/vhost.h | 20 ++-
4 files changed, 397 insertions(+), 14 deletions(-)