In virtio-spec 1.1, new feature bit VIRTIO_F_IN_ORDER was introduced. When this feature has been negotiated, virtio driver will use descriptors in ring order: starting from offset 0 in the table, and wrapping around at the end of the table. Vhost devices will always use descriptors in the same order in which they have been made available. This can reduce virtio accesses to used ring. Based on updated virtio-spec, this series realized IN_ORDER prototype in virtio driver and vhost. Currently IN_ORDER feature supported devices are *vhost_test* and *vsock*, and IN_ORDER feature works well combined with INDIRECT feature in this patch series. Some work haven't been done in this patch series: 1. Virtio driver in_order support for packed vq is left for the future. Guo Zhi (7): vhost: expose used buffers vhost_test: batch used buffer vsock: batch buffers in tx vsock: announce VIRTIO_F_IN_ORDER in vsock virtio: unmask F_NEXT flag in desc_extra virtio: in order support for virtio_ring virtio: annouce VIRTIO_F_IN_ORDER support drivers/vhost/test.c | 8 ++++- drivers/vhost/vhost.c | 14 +++++++-- drivers/vhost/vhost.h | 1 + drivers/vhost/vsock.c | 10 +++++- drivers/virtio/virtio_ring.c | 61 ++++++++++++++++++++++++++++++------ 5 files changed, 80 insertions(+), 14 deletions(-) -- 2.17.1
