Hmm I sent a bit too fast, and my testing rig is down now. So please do send a new version, I sent comments on what to fix in this one.
On Fri, Mar 24, 2023 at 02:08:55AM -0400, Michael S. Tsirkin wrote: > Thanks for the patch! > I picked it up. > I made small changes, please look at it in my branch, > both to see what I changed for your next submission, > and to test that it still addresses the problem for you. > Waiting for your confirmation to send upstream. > Thanks! > > > On Tue, Mar 21, 2023 at 04:59:53PM +0800, Albert Huang wrote: > > From: "huangjie.albert" <[email protected]> > > > > fix commit 8d622d21d248 ("virtio: fix up virtio_disable_cb") > > > > if we disable the napi_tx. when we triger a tx interrupt, the > > vq->event_triggered will be set to true. It will no longer be > > set to false. Unless we explicitly call virtqueue_enable_cb_delayed > > or virtqueue_enable_cb_prepare > > > > if we disable the napi_tx, It will only be called when the tx ring > > buffer is relatively small: > > virtio_net->start_xmit: > > if (sq->vq->num_free < 2+MAX_SKB_FRAGS) { > > netif_stop_subqueue(dev, qnum); > > if (!use_napi && > > unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { > > /* More just got used, free them then recheck. */ > > free_old_xmit_skbs(sq, false); > > if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) { > > netif_start_subqueue(dev, qnum); > > virtqueue_disable_cb(sq->vq); > > } > > } > > } > > Because event_triggered is true.Therefore, VRING_AVAIL_F_NO_INTERRUPT or > > VRING_PACKED_EVENT_FLAG_DISABLE will not be set.So we update > > vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap > > every time we call virtqueue_get_buf_ctx.This will bring more interruptions. > > > > if event_triggered is set to true, do not update > > vring_used_event(&vq->split.vring) > > or vq->packed.vring.driver->off_wrap > > > > Signed-off-by: huangjie.albert <[email protected]> > > --- > > drivers/virtio/virtio_ring.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 307e139cb11d..f486cccadbeb 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -795,7 +795,8 @@ static void *virtqueue_get_buf_ctx_split(struct > > virtqueue *_vq, > > /* If we expect an interrupt for the next entry, tell host > > * by writing event index and flush out the write before > > * the read in the next get_buf call. */ > > - if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) > > + if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) > > + && (vq->event_triggered == false)) > > virtio_store_mb(vq->weak_barriers, > > &vring_used_event(&vq->split.vring), > > cpu_to_virtio16(_vq->vdev, vq->last_used_idx)); > > @@ -1529,7 +1530,8 @@ static void *virtqueue_get_buf_ctx_packed(struct > > virtqueue *_vq, > > * by writing event index and flush out the write before > > * the read in the next get_buf call. > > */ > > - if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC) > > + if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC > > + && (vq->event_triggered == false)) > > virtio_store_mb(vq->weak_barriers, > > &vq->packed.vring.driver->off_wrap, > > cpu_to_le16(vq->last_used_idx)); > > -- > > 2.31.1 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
