[patch net-next] virtio_net: add support for Byte Queue Limits

Jiri Pirko
2024-05-09T11:46:21Z

From: Jiri Pirko <jiri@nvidia.com>

Add support for Byte Queue Limits (BQL).

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
drivers/net/virtio_net.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 218a446c4c27..c53d6dc6d332 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -84,7 +84,9 @@ struct virtnet_stat_desc {

struct virtnet_sq_free_stats {
u64 packets;
+ u64 xdp_packets;
u64 bytes;
+ u64 xdp_bytes;
};

struct virtnet_sq_stats {
@@ -512,19 +514,19 @@ static void __free_old_xmit(struct send_queue *sq, bool in_napi,
void *ptr;

while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
- ++stats->packets;
-
if (!is_xdp_frame(ptr)) {
struct sk_buff *skb = ptr;

pr_debug("Sent skb %p\n", skb);

+ stats->packets++;
stats->bytes += skb->len;
napi_consume_skb(skb, in_napi);
} else {
struct xdp_frame *frame = ptr_to_xdp(ptr);

- stats->bytes += xdp_get_frame_len(frame);
+ stats->xdp_packets++;
+ stats->xdp_bytes += xdp_get_frame_len(frame);
xdp_return_frame(frame);
}
}
@@ -965,7 +967,8 @@ static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
virtnet_rq_free_buf(vi, rq, buf);
}

-static void free_old_xmit(struct send_queue *sq, bool in_napi)
+static void free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
+ bool in_napi)
{
struct virtnet_sq_free_stats stats = {0};

@@ -974,9 +977,11 @@ static void free_old_xmit(struct send_queue *sq, bool in_napi)
/* Avoid overhead when no packets have been processed
* happens when called speculatively from start_xmit.
*/
- if (!stats.packets)
+ if (!stats.packets && !stats.xdp_packets)
return;

+ netdev_tx_completed_queue(txq, stats.packets, stats.bytes);
+
u64_stats_update_begin(&sq->stats.syncp);
u64_stats_add(&sq->stats.bytes, stats.bytes);
u64_stats_add(&sq->stats.packets, stats.packets);
@@ -1013,13 +1018,15 @@ static void check_sq_full_and_disable(struct virtnet_info *vi,
* early means 16 slots are typically wasted.
*/
if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
- netif_stop_subqueue(dev, qnum);
+ struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
+
+ netif_tx_stop_queue(txq);
if (use_napi) {
if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
virtqueue_napi_schedule(&sq->napi, sq->vq);
} else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
/* More just got used, free them then recheck. */
- free_old_xmit(sq, false);
+ free_old_xmit(sq, txq, false);
if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
netif_start_subqueue(dev, qnum);
virtqueue_disable_cb(sq->vq);
@@ -2319,7 +2326,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)

do {
virtqueue_disable_cb(sq->vq);
- free_old_xmit(sq, true);
+ free_old_xmit(sq, txq, true);
} while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));

if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
@@ -2471,7 +2478,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
txq = netdev_get_tx_queue(vi->dev, index);
__netif_tx_lock(txq, raw_smp_processor_id());
virtqueue_disable_cb(sq->vq);
- free_old_xmit(sq, true);
+ free_old_xmit(sq, txq, true);

if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
netif_tx_wake_queue(txq);
@@ -2553,7 +2560,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
struct send_queue *sq = &vi->sq[qnum];
int err;
struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
- bool kick = !netdev_xmit_more();
+ bool xmit_more = netdev_xmit_more();
bool use_napi = sq->napi.weight;

/* Free up any pending old buffers before queueing new ones. */
@@ -2561,9 +2568,9 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
if (use_napi)
virtqueue_disable_cb(sq->vq);

- free_old_xmit(sq, false);
+ free_old_xmit(sq, txq, false);

- } while (use_napi && kick &&
+ } while (use_napi && !xmit_more &&
unlikely(!virtqueue_enable_cb_delayed(sq->vq)));

/* timestamp packet in software */
@@ -2592,7 +2599,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)

check_sq_full_and_disable(vi, dev, sq);

- if (kick || netif_xmit_stopped(txq)) {
+ if (__netdev_tx_sent_queue(txq, skb->len, xmit_more)) {
if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
u64_stats_update_begin(&sq->stats.syncp);
u64_stats_inc(&sq->stats.kicks);
--
2.44.0