On Fri, 3 Feb 2023 03:33:41 -0500, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> On Fri, Feb 03, 2023 at 11:24:42AM +0800, Xuan Zhuo wrote:
> > On Thu, 2 Feb 2023 12:25:59 -0500, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> > > On Thu, Feb 02, 2023 at 07:00:49PM +0800, Xuan Zhuo wrote:
> > > > Since xsk's TX queue is consumed by TX NAPI, if sq is bound to xsk, then
> > > > we must stop tx napi from being disabled.
> > > >
> > > > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > > > ---
> > > > drivers/net/virtio/main.c | 9 ++++++++-
> > > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
> > > > index ed79e750bc6c..232cf151abff 100644
> > > > --- a/drivers/net/virtio/main.c
> > > > +++ b/drivers/net/virtio/main.c
> > > > @@ -2728,8 +2728,15 @@ static int virtnet_set_coalesce(struct net_device *dev,
> > > > return ret;
> > > >
> > > > if (update_napi) {
> > > > - for (i = 0; i < vi->max_queue_pairs; i++)
> > > > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > > > + /* xsk xmit depend on the tx napi. So if xsk is active,
> > >
> > > depends.
> > >
> > > > + * prevent modifications to tx napi.
> > > > + */
> > > > + if (rtnl_dereference(vi->sq[i].xsk.pool))
> > > > + continue;
> > > > +
> > > > vi->sq[i].napi.weight = napi_weight;
> > >
> > > I don't get it.
> > > changing napi weight does not work then.
> > > why is this ok?
> >
> >
> > static void skb_xmit_done(struct virtqueue *vq)
> > {
> > struct virtnet_info *vi = vq->vdev->priv;
> > struct napi_struct *napi = &vi->sq[vq2txq(vq)].napi;
> >
> > /* Suppress further interrupts. */
> > virtqueue_disable_cb(vq);
> >
> > if (napi->weight)
> > virtqueue_napi_schedule(napi, vq);
> > else
> > /* We were probably waiting for more output buffers. */
> > netif_wake_subqueue(vi->dev, vq2txq(vq));
> > }
> >
> >
> > If the weight is 0, tx napi will not be triggered again.
> >
> > Thanks.
>
> This needs more thought then. First ignoring what user is requesting is
> not nice.
Maybe we should return an error.
>Second what if napi is first disabled and then xsk enabled?
static int virtnet_xsk_pool_enable(struct net_device *dev,
struct xsk_buff_pool *pool,
u16 qid)
{
struct virtnet_info *vi = netdev_priv(dev);
struct receive_queue *rq;
struct send_queue *sq;
int err;
if (qid >= vi->curr_queue_pairs)
return -EINVAL;
sq = &vi->sq[qid];
rq = &vi->rq[qid];
/* xsk zerocopy depend on the tx napi.
*
* All xsk packets are actually consumed and sent out from the xsk tx
* queue under the tx napi mechanism.
*/
-> if (!sq->napi.weight)
return -EPERM;
Thanks.
>
>
> > >
> > >
> > > > + }
> > > > }
> > > >
> > > > return ret;
> > > > --
> > > > 2.32.0.3.g01195cf9f
> > >
>
