virtio_net: Add kick stats

So we can infer the number of VM-Exits.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index cb4ef33..1880c86 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -84,6 +84,7 @@ struct virtnet_sq_stats {
        u64 bytes;
        u64 xdp_tx;
        u64 xdp_tx_drops;
+       u64 kicks;
 };
 
 struct virtnet_rq_stat_items {
@@ -94,6 +95,7 @@ struct virtnet_rq_stat_items {
        u64 xdp_tx;
        u64 xdp_redirects;
        u64 xdp_drops;
+       u64 kicks;
 };
 
 struct virtnet_rq_stats {
@@ -117,6 +119,7 @@ static const struct virtnet_stat_desc virtnet_sq_stats_desc[] = {
        { "bytes",              VIRTNET_SQ_STAT(bytes) },
        { "xdp_tx",             VIRTNET_SQ_STAT(xdp_tx) },
        { "xdp_tx_drops",       VIRTNET_SQ_STAT(xdp_tx_drops) },
+       { "kicks",              VIRTNET_SQ_STAT(kicks) },
 };
 
 static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
@@ -127,6 +130,7 @@ static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
        { "xdp_tx",             VIRTNET_RQ_STAT(xdp_tx) },
        { "xdp_redirects",      VIRTNET_RQ_STAT(xdp_redirects) },
        { "xdp_drops",          VIRTNET_RQ_STAT(xdp_drops) },
+       { "kicks",              VIRTNET_RQ_STAT(kicks) },
 };
 
 #define VIRTNET_SQ_STATS_LEN   ARRAY_SIZE(virtnet_sq_stats_desc)
@@ -507,6 +511,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
        struct send_queue *sq;
        unsigned int len;
        int drops = 0;
+       int kicks = 0;
        int ret, err;
        int i;
 
@@ -543,12 +548,15 @@ static int virtnet_xdp_xmit(struct net_device *dev,
        }
        ret = n - drops;
 
-       if (flags & XDP_XMIT_FLUSH)
-               virtqueue_kick(sq->vq);
+       if (flags & XDP_XMIT_FLUSH) {
+               if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq))
+                       kicks = 1;
+       }
 out:
        u64_stats_update_begin(&sq->stats.syncp);
        sq->stats.xdp_tx += n;
        sq->stats.xdp_tx_drops += drops;
+       sq->stats.kicks += kicks;
        u64_stats_update_end(&sq->stats.syncp);
 
        return ret;
@@ -1226,7 +1234,12 @@ static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq,
                if (err)
                        break;
        } while (rq->vq->num_free);
-       virtqueue_kick(rq->vq);
+       if (virtqueue_kick_prepare(rq->vq) && virtqueue_notify(rq->vq)) {
+               u64_stats_update_begin(&rq->stats.syncp);
+               rq->stats.items.kicks++;
+               u64_stats_update_end(&rq->stats.syncp);
+       }
+
        return !oom;
 }
 
@@ -1416,7 +1429,11 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
 
        if (xdp_xmit & VIRTIO_XDP_TX) {
                sq = virtnet_xdp_sq(vi);
-               virtqueue_kick(sq->vq);
+               if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
+                       u64_stats_update_begin(&sq->stats.syncp);
+                       sq->stats.kicks++;
+                       u64_stats_update_end(&sq->stats.syncp);
+               }
        }
 
        return received;
@@ -1578,8 +1595,13 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
                }
        }
 
-       if (kick || netif_xmit_stopped(txq))
-               virtqueue_kick(sq->vq);
+       if (kick || netif_xmit_stopped(txq)) {
+               if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
+                       u64_stats_update_begin(&sq->stats.syncp);
+                       sq->stats.kicks++;
+                       u64_stats_update_end(&sq->stats.syncp);
+               }
+       }
 
        return NETDEV_TX_OK;
 }