From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH net-next 2/6] virtio: introduce virtio_enable_cb_avail() Date: Wed, 15 Oct 2014 12:28:49 +0300 Message-ID: <20141015092849.GA25776@redhat.com> References: <1413357930-45302-1-git-send-email-jasowang@redhat.com> <1413357930-45302-3-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, davem@davemloft.net To: Jason Wang Return-path: Content-Disposition: inline In-Reply-To: <1413357930-45302-3-git-send-email-jasowang@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Wed, Oct 15, 2014 at 03:25:26PM +0800, Jason Wang wrote: > This patch introduces virtio_enable_cb_avail() to publish avail idx > and used event. This could be used by batched buffer submitting to > reduce the number of tx interrupts. > > Cc: Rusty Russell > Cc: Michael S. Tsirkin > Signed-off-by: Jason Wang > --- > drivers/virtio/virtio_ring.c | 22 ++++++++++++++++++++-- > include/linux/virtio.h | 2 ++ > 2 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 1b3929f..d67fbf8 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -567,14 +567,32 @@ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) > * entry. Always do both to keep code simple. */ > vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; > /* Make sure used event never go backwards */ > - if (!vring_need_event(vring_used_event(&vq->vring), > - vq->vring.avail->idx, last_used_idx)) > + if (vq->vring.avail->idx != vring_used_event(&vq->vring) && > + !vring_need_event(vring_used_event(&vq->vring), > + vq->vring.avail->idx, last_used_idx)) { > vring_used_event(&vq->vring) = last_used_idx; > + } > END_USE(vq); > return last_used_idx; > } > EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); > I see you are also changing virtqueue_enable_cb_prepare, why? > +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) > +{ > + struct vring_virtqueue *vq = to_vvq(_vq); > + bool ret; > + > + START_USE(vq); > + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; > + vring_used_event(&vq->vring) = vq->vring.avail->idx; > + ret = vring_need_event(vq->vring.avail->idx, > + vq->last_used_idx, vq->vring.used->idx); > + END_USE(vq); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(virtqueue_enable_cb_avail); > + > /** > * virtqueue_poll - query pending used buffers > * @vq: the struct virtqueue we're talking about. Could not figure out what this does. Please add documentation. > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index b46671e..bfaf058 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -65,6 +65,8 @@ bool virtqueue_enable_cb(struct virtqueue *vq); > > unsigned virtqueue_enable_cb_prepare(struct virtqueue *vq); > > +bool virtqueue_enable_cb_avail(struct virtqueue *vq); > + > bool virtqueue_poll(struct virtqueue *vq, unsigned); > > bool virtqueue_enable_cb_delayed(struct virtqueue *vq); > -- > 1.7.1