Hi: This series tries to access virtqueue metadata through kernel virtual address instead of copy_user() friends since they had too much overheads like checks, spec barriers or even hardware feature toggling. Test shows about 24% improvement on TX PPS. It should benefit other cases as well. Please review Jason Wang (3): vhost: generalize adding used elem vhost: fine grain userspace memory accessors vhost: access vq metadata through kernel virtual address drivers/vhost/vhost.c | 281 ++++++++++++++++++++++++++++++++++++++---- drivers/vhost/vhost.h | 11 ++ 2 files changed, 266 insertions(+), 26 deletions(-) -- 2.17.1