[dpdk-dev] [PATCH v3 20/21] net/virtio: add support for event suppression

Maxime Coquelin maxime.coquelin at redhat.com
Fri Apr 6 15:50:28 CEST 2018



On 04/05/2018 12:10 PM, Jens Freimann wrote:
> Signed-off-by: Jens Freimann <jfreimann at redhat.com>
> ---
>   drivers/net/virtio/virtio_ethdev.c |  2 +-
>   drivers/net/virtio/virtio_ethdev.h |  2 +-
>   drivers/net/virtio/virtio_rxtx.c   | 15 +++++++-
>   drivers/net/virtio/virtqueue.h     | 73 ++++++++++++++++++++++++++++++++++++--
>   4 files changed, 86 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index a3c3376d7..65a6a9d89 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -727,7 +727,7 @@ virtio_dev_rx_queue_intr_enable(struct rte_eth_dev *dev, uint16_t queue_id)
>   	struct virtnet_rx *rxvq = dev->data->rx_queues[queue_id];
>   	struct virtqueue *vq = rxvq->vq;
>   
> -	virtqueue_enable_intr(vq);
> +	virtqueue_enable_intr(vq, 0, 0);
>   	return 0;
>   }
>   
> diff --git a/drivers/net/virtio/virtio_ethdev.h b/drivers/net/virtio/virtio_ethdev.h
> index 3aeced4bb..19d3f2617 100644
> --- a/drivers/net/virtio/virtio_ethdev.h
> +++ b/drivers/net/virtio/virtio_ethdev.h
> @@ -37,7 +37,7 @@
>   	 1u << VIRTIO_RING_F_INDIRECT_DESC |    \
>   	 1ULL << VIRTIO_F_VERSION_1       |	\
>   	 1ULL << VIRTIO_F_RING_PACKED     |	\
> -	 1ULL << VIRTIO_F_IOMMU_PLATFORM)
> +	 1ULL << VIRTIO_RING_F_EVENT_IDX)
>   
>   #define VIRTIO_PMD_SUPPORTED_GUEST_FEATURES	\
>   	(VIRTIO_PMD_DEFAULT_GUEST_FEATURES |	\
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index a48ca6aaa..ed65434ce 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -127,6 +127,10 @@ virtio_xmit_pkts_packed(void *tx_queue, struct rte_mbuf **tx_pkts,
>   
>   		rte_smp_wmb();
>   		_set_desc_avail(&desc[head_idx], wrap_counter);
> +		if (unlikely(virtqueue_kick_prepare_packed(vq))) {
> +				virtqueue_notify(vq);
> +				PMD_RX_LOG(DEBUG, "Notified");
> +		}
>   	}
>   
>   	txvq->stats.packets += i;
> @@ -998,6 +1002,10 @@ virtio_recv_pkts_packed(void *rx_queue, struct rte_mbuf **rx_pkts,
>   	}
>   
>   	rxvq->stats.packets += nb_rx;
> +	if (nb_rx > 0 && unlikely(virtqueue_kick_prepare_packed(vq))) {
> +		virtqueue_notify(vq);
> +		PMD_RX_LOG(DEBUG, "Notified");
> +	}
>   
>   	vq->vq_used_cons_idx = used_idx;
>   
> @@ -1276,8 +1284,13 @@ virtio_recv_mergeable_pkts(void *rx_queue,
>   
>   	rxvq->stats.packets += nb_rx;
>   
> -	if (vtpci_packed_queue(vq->hw))
> +	if (vtpci_packed_queue(vq->hw)) {
> +		if (unlikely(virtqueue_kick_prepare(vq))) {
> +			virtqueue_notify(vq);
> +			PMD_RX_LOG(DEBUG, "Notified");
> +		}
>   		return nb_rx;
> +	}
>   
>   	/* Allocate new mbuf for the used descriptor */
>   	error = ENOSPC;
> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
> index 7196bd717..6fd3317d2 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -176,6 +176,8 @@ struct virtqueue {
>   	uint16_t vq_free_cnt;  /**< num of desc available */
>   	uint16_t vq_avail_idx; /**< sync until needed */
>   	uint16_t vq_free_thresh; /**< free threshold */
> +	uint16_t vq_signalled_avail;
> +	int vq_signalled_avail_valid;
>   
>   	void *vq_ring_virt_mem;  /**< linear address of vring*/
>   	unsigned int vq_ring_size;
> @@ -273,16 +275,34 @@ vring_desc_init(struct vring_desc *dp, uint16_t n)
>   static inline void
>   virtqueue_disable_intr(struct virtqueue *vq)
>   {
> -	vq->vq_ring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
> +	if (vtpci_packed_queue(vq->hw) && vtpci_with_feature(vq->hw,
> +				VIRTIO_RING_F_EVENT_IDX))
> +		vq->vq_ring.device_event->desc_event_flags = RING_EVENT_FLAGS_DISABLE;
> +	else
> +		vq->vq_ring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
>   }
>   
>   /**
>    * Tell the backend to interrupt us.
>    */
>   static inline void
> -virtqueue_enable_intr(struct virtqueue *vq)
> +virtqueue_enable_intr(struct virtqueue *vq, uint16_t off, uint16_t wrap_counter)
>   {
> -	vq->vq_ring.avail->flags &= (~VRING_AVAIL_F_NO_INTERRUPT);
> +	uint16_t *flags = &vq->vq_ring.device_event->desc_event_flags;
> +	uint16_t *event_off_wrap = &vq->vq_ring.device_event->desc_event_off_wrap;
> +	if (vtpci_packed_queue(vq->hw)) {
> +		*flags = 0;
> +		*event_off_wrap = 0;
> +		if (*event_off_wrap & RING_EVENT_FLAGS_DESC) {
> +			*event_off_wrap = off | 0x7FFF;
> +			*event_off_wrap |= wrap_counter << 15;
> +			*flags |= RING_EVENT_FLAGS_DESC;
> +		} else
> +			*event_off_wrap = 0;
> +		*flags |= RING_EVENT_FLAGS_ENABLE;
> +	} else {
> +		vq->vq_ring.avail->flags &= (~VRING_AVAIL_F_NO_INTERRUPT);
> +	}
>   }
>   
>   /**
> @@ -342,12 +362,59 @@ vq_update_avail_ring(struct virtqueue *vq, uint16_t desc_idx)
>   	vq->vq_avail_idx++;
>   }
>   
> +static int vhost_idx_diff(struct virtqueue *vq, uint16_t old, uint16_t new)
> +{
> +	if (new > old)
> +		return new - old;
> +	return  (new + vq->vq_nentries - old);
> +}
> +
> +static int vring_packed_need_event(struct virtqueue *vq,
> +		uint16_t event_off, uint16_t new,
> +		uint16_t old)
> +{
> +	return (uint16_t)(vhost_idx_diff(vq, new, event_off) - 1) <
> +		(uint16_t)vhost_idx_diff(vq, new, old);
> +}
> +
> +
>   static inline int
>   virtqueue_kick_prepare(struct virtqueue *vq)
>   {
>   	return !(vq->vq_ring.used->flags & VRING_USED_F_NO_NOTIFY);
>   }
>   
> +static inline int
> +virtqueue_kick_prepare_packed(struct virtqueue *vq)
> +{
> +	uint16_t notify_offset, flags, wrap;
> +	uint16_t old, new;
> +	int v;
> +
> +	if (vtpci_packed_queue(vq->hw)) {
> +		flags = vq->vq_ring.device_event->desc_event_flags;
> +		if (!(flags & RING_EVENT_FLAGS_DESC))
> +			return flags & RING_EVENT_FLAGS_ENABLE;
> +		virtio_rmb();
> +		notify_offset = vq->vq_ring.device_event->desc_event_off_wrap;
> +		wrap = notify_offset & 0x1;
> +		notify_offset >>= 1;
> +
> +		old = vq->vq_signalled_avail;
> +		v = vq->vq_signalled_avail_valid;
> +		new = vq->vq_signalled_avail = vq->vq_avail_idx;
> +		vq->vq_signalled_avail_valid = 1;
> +
> +		if (unlikely(!v))
> +			return 0;
> +
> +		return (vring_packed_need_event(vq, new, old, notify_offset) &&
> +			wrap == vq->vq_ring.avail_wrap_counter);
> +	} else {
> +		return !(vq->vq_ring.used->flags & VRING_USED_F_NO_NOTIFY);

Maybe I didn't gezt it, but it looks confusing that the function name
contains packed, and that it seems it handles non-packed queue case.

> +	}
> +}
> +
>   static inline void
>   virtqueue_notify(struct virtqueue *vq)
>   {
> 


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