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

Message

Michael S. Tsirkin Oct. 12, 2019, 7:18 p.m. UTC

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(-)