lkml.org 
[lkml]   [2018]   [Apr]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC v3 0/5] virtio: support packed ring
From
Date


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

>
> 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(-)
>

\
 
 \ /
  Last update: 2018-04-27 05:56    [W:0.186 / U:4.688 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site