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

[Jens Freimann]

On Fri, Apr 06, 2018 at 03:50:28PM +0200, Maxime Coquelin wrote:
>
>
>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.

No, the else part is not needed here. I'll remove it and make sure to
call the right function.

Thanks!

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