On Wed, Nov 21, 2018 at 06:03:17PM +0800, Tiwei Bie wrote: > 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 I went over it and I think it's correct spec-wise. I have some ideas for enhancements but let's start with getting this stuff merged first. Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > 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
