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virtio_net: Make drop counter per-queue

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Since when XDP was introduced, drop counter has been able to be updated
much more frequently than before, as XDP_DROP increments the counter.
Thus for performance analysis per-queue drop counter would be useful.

Also this avoids cache contention and race on updating the counter. It
is currently racy because napi handlers read-modify-write it without any
locks.

There are more counters in dev->stats that are racy, but I left them
per-device, because they are rarely updated and does not worth being
per-queue counters IMHO. To fix them we need atomic ops or some kind of
locks.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Toshiaki Makita 2018-07-23 23:36:06 +09:00 committed by David S. Miller
parent a0929a44c2
commit 2c4a2f7d82
1 changed files with 8 additions and 5 deletions
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13
drivers/net/virtio_net.c
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@ -87,6 +87,7 @@ struct virtnet_sq_stats {
struct virtnet_rq_stat_items {
u64 packets;
u64 bytes;
u64 drops;
};
struct virtnet_rq_stats {
@ -109,6 +110,7 @@ static const struct virtnet_stat_desc virtnet_sq_stats_desc[] = {
static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
{ "packets", VIRTNET_RQ_STAT(packets) },
{ "bytes", VIRTNET_RQ_STAT(bytes) },
{ "drops", VIRTNET_RQ_STAT(drops) },
};
#define VIRTNET_SQ_STATS_LEN ARRAY_SIZE(virtnet_sq_stats_desc)
@ -705,7 +707,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
err_xdp:
rcu_read_unlock();
dev->stats.rx_dropped++;
stats->rx.drops++;
put_page(page);
xdp_xmit:
return NULL;
@ -728,7 +730,7 @@ static struct sk_buff *receive_big(struct net_device *dev,
return skb;
err:
dev->stats.rx_dropped++;
stats->rx.drops++;
give_pages(rq, page);
return NULL;
}
@ -952,7 +954,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
put_page(page);
}
err_buf:
dev->stats.rx_dropped++;
stats->rx.drops++;
dev_kfree_skb(head_skb);
xdp_xmit:
return NULL;
@ -1632,7 +1634,7 @@ static void virtnet_stats(struct net_device *dev,
int i;
for (i = 0; i < vi->max_queue_pairs; i++) {
u64 tpackets, tbytes, rpackets, rbytes;
u64 tpackets, tbytes, rpackets, rbytes, rdrops;
struct receive_queue *rq = &vi->rq[i];
struct send_queue *sq = &vi->sq[i];
@ -1646,17 +1648,18 @@ static void virtnet_stats(struct net_device *dev,
start = u64_stats_fetch_begin_irq(&rq->stats.syncp);
rpackets = rq->stats.items.packets;
rbytes = rq->stats.items.bytes;
rdrops = rq->stats.items.drops;
} while (u64_stats_fetch_retry_irq(&rq->stats.syncp, start));
tot->rx_packets += rpackets;
tot->tx_packets += tpackets;
tot->rx_bytes += rbytes;
tot->tx_bytes += tbytes;
tot->rx_dropped += rdrops;
}
tot->tx_dropped = dev->stats.tx_dropped;
tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
tot->rx_dropped = dev->stats.rx_dropped;
tot->rx_length_errors = dev->stats.rx_length_errors;
tot->rx_frame_errors = dev->stats.rx_frame_errors;
}