On 2019/10/13 下午7:41, Michael S. Tsirkin wrote:
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 v3:
- fixed error handling in case of indirect descriptors
- add BUG_ON to detect buffer overflow in case of bugs
in response to comment by Jason Wang
- minor code tweaks
Changes from v2:
- fixed indirect descriptor batching
reported by Jason Wang
Changes from v1:
- typo fixes
I've just done some quick benchmark with testpmd + vhost_net txonly.
With 256 queue size, no difference but in 1024 queue size 1% regression
of PPS were found.
Thanks
Michael S. Tsirkin (5):
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
vhost: last descriptor must have NEXT clear
drivers/vhost/net.c | 32 ++++-
drivers/vhost/test.c | 19 ++-
drivers/vhost/vhost.c | 328 +++++++++++++++++++++++++++++++++++++++++-
drivers/vhost/vhost.h | 20 ++-
4 files changed, 385 insertions(+), 14 deletions(-)
