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(-) -- MST
