Hi, This patch set implements packed ring support in virtio driver. A performance test between pktgen (pktgen_sample03_burst_single_flow.sh) and DPDK vhost (testpmd/rxonly/vhost-PMD) has been done, I saw ~30% performance gain in packed ring in this case. To make this patch set work with below patch set for vhost, some hacks are needed to set the _F_NEXT flag in indirect descriptors (this should be fixed in vhost): https://lkml.org/lkml/2018/7/3/33 v2 -> v3: - Use leXX instead of virtioXX (MST); - Refactor split ring first (MST); - Add debug helpers (MST); - Put split/packed ring specific fields in sub structures (MST); - Handle normal descriptors and indirect descriptors differently (MST); - Track the DMA addr/len related info in a separate structure (MST); - Calculate AVAIL/USED flags only when wrap counter wraps (MST); - Define a struct/union to read event structure (MST); - Define a macro for wrap counter bit in uapi (MST); - Define the AVAIL/USED bits as shifts instead of values (MST); - s/_F_/_FLAG_/ in VRING_PACKED_EVENT_* as they are values (MST); - Drop the notify workaround for QEMU's tx-timer in packed ring (MST); v1 -> v2: - Use READ_ONCE() to read event off_wrap and flags together (Jason); - Add comments related to ccw (Jason); RFC v6 -> v1: - Avoid extra virtio_wmb() in virtqueue_enable_cb_delayed_packed() when event idx is off (Jason); - Fix bufs calculation in virtqueue_enable_cb_delayed_packed() (Jason); - Test the state of the desc at used_idx instead of last_used_idx in virtqueue_enable_cb_delayed_packed() (Jason); - Save wrap counter (as part of queue state) in the return value of virtqueue_enable_cb_prepare_packed(); - Refine the packed ring definitions in uapi; - Rebase on the net-next tree; RFC v5 -> RFC v6: - Avoid tracking addr/len/flags when DMA API isn't used (MST/Jason); - Define wrap counter as bool (Jason); - Use ALIGN() in vring_init_packed() (Jason); - Avoid using pointer to track `next` in detach_buf_packed() (Jason); - Add comments for barriers (Jason); - Don't enable RING_PACKED on ccw for now (noticed by Jason); - Refine the memory barrier in virtqueue_poll(); - Add a missing memory barrier in virtqueue_enable_cb_delayed_packed(); - Remove the hacks in virtqueue_enable_cb_prepare_packed(); RFC v4 -> RFC v5: - Save DMA addr, etc in desc state (Jason); - Track used wrap counter; RFC v3 -> RFC v4: - Make ID allocation support out-of-order (Jason); - Various fixes for EVENT_IDX support; RFC v2 -> RFC v3: - Split into small patches (Jason); - Add helper virtqueue_use_indirect() (Jason); - Just set id for the last descriptor of a list (Jason); - Calculate the prev in virtqueue_add_packed() (Jason); - Fix/improve desc suppression code (Jason/MST); - Refine the code layout for XXX_split/packed and wrappers (MST); - Fix the comments and API in uapi (MST); - Remove the BUG_ON() for indirect (Jason); - Some other refinements and bug fixes; RFC v1 -> RFC v2: - Add indirect descriptor support - compile test only; - Add event suppression supprt - compile test only; - Move vring_packed_init() out of uapi (Jason, MST); - Merge two loops into one in virtqueue_add_packed() (Jason); - Split vring_unmap_one() for packed ring and split ring (Jason); - Avoid using '%' operator (Jason); - Rename free_head -> next_avail_idx (Jason); - Add comments for virtio_wmb() in virtqueue_add_packed() (Jason); - Some other refinements and bug fixes; Tiwei Bie (13): virtio: add packed ring types and macros virtio_ring: add _split suffix for split ring functions virtio_ring: put split ring functions together virtio_ring: put split ring fields in a sub struct virtio_ring: introduce debug helpers virtio_ring: introduce helper for indirect feature virtio_ring: allocate desc state for split ring separately virtio_ring: extract split ring handling from ring creation virtio_ring: cache whether we will use DMA API virtio_ring: introduce packed ring support virtio_ring: leverage event idx in packed ring virtio_ring: disable packed ring on unsupported transports virtio_ring: advertize packed ring layout drivers/misc/mic/vop/vop_main.c | 13 + drivers/remoteproc/remoteproc_virtio.c | 13 + drivers/s390/virtio/virtio_ccw.c | 14 + drivers/virtio/virtio_ring.c | 1811 +++++++++++++++++++++++++------- include/uapi/linux/virtio_config.h | 3 + include/uapi/linux/virtio_ring.h | 52 + 6 files changed, 1530 insertions(+), 376 deletions(-) -- 2.14.5 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
