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

Message

Michael S. Tsirkin Oct. 13, 2019, 8:07 a.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.
Lightly tested.
More testing would be very much appreciated.

To use new code:
	echo 1 > /sys/module/vhost_test/parameters/newcode
or
	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(-)