On Fri, Apr 27, 2018 at 11:56:05AM +0800, Jason Wang wrote: > > > On 2018年04月25日 13:15, Tiwei Bie wrote: > > Hello everyone, > > > > This RFC implements packed ring support in virtio driver. > > > > Some simple functional tests have been done with Jason's > > packed ring implementation in vhost: > > > > https://lkml.org/lkml/2018/4/23/12 > > > > Both of ping and netperf worked as expected (with EVENT_IDX > > disabled). But there are below known issues: > > > > 1. Reloading the guest driver will break the Tx/Rx; > > Will have a look at this issue. > > > 2. Zeroing the flags when detaching a used desc will > > break the guest -> host path. > > I still think zeroing flags is unnecessary or even a bug. At host, I track > last observed avail wrap counter and detect avail like (what is suggested in > the example code in the spec): > > static bool desc_is_avail(struct vhost_virtqueue *vq, __virtio16 flags) > { > bool avail = flags & cpu_to_vhost16(vq, DESC_AVAIL); > > return avail == vq->avail_wrap_counter; > } > > So zeroing wrap can not work with this obviously. > > Thanks I agree. I think what one should do is flip the available bit. > > > > Some simple functional tests have also been done with > > Wei's packed ring implementation in QEMU: > > > > http://lists.nongnu.org/archive/html/qemu-devel/2018-04/msg00342.html > > > > Both of ping and netperf worked as expected (with EVENT_IDX > > disabled). Reloading the guest driver also worked as expected. > > > > TODO: > > - Refinements (for code and commit log) and bug fixes; > > - Discuss/fix/test EVENT_IDX support; > > - Test devices other than net; > > > > 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; > > > > Thanks! > > > > Tiwei Bie (5): > > virtio: add packed ring definitions > > virtio_ring: support creating packed ring > > virtio_ring: add packed ring support > > virtio_ring: add event idx support in packed ring > > virtio_ring: enable packed ring > > > > drivers/virtio/virtio_ring.c | 1271 ++++++++++++++++++++++++++++-------- > > include/linux/virtio_ring.h | 8 +- > > include/uapi/linux/virtio_config.h | 12 +- > > include/uapi/linux/virtio_ring.h | 36 + > > 4 files changed, 1049 insertions(+), 278 deletions(-) > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
