Mon, May 20, 2024 at 02:48:15PM CEST, jiri@xxxxxxxxxxx wrote: >Fri, May 10, 2024 at 09:11:16AM CEST, hengqi@xxxxxxxxxxxxxxxxx wrote: >>On Thu, 9 May 2024 13:46:15 +0200, Jiri Pirko <jiri@xxxxxxxxxxx> wrote: >>> From: Jiri Pirko <jiri@xxxxxxxxxx> >>> >>> Add support for Byte Queue Limits (BQL). >> >>Historically both Jason and Michael have attempted to support BQL >>for virtio-net, for example: >> >>https://lore.kernel.org/netdev/21384cb5-99a6-7431-1039-b356521e1bc3@xxxxxxxxxx/ >> >>These discussions focus primarily on: >> >>1. BQL is based on napi tx. Therefore, the transfer of statistical information >>needs to rely on the judgment of use_napi. When the napi mode is switched to >>orphan, some statistical information will be lost, resulting in temporary >>inaccuracy in BQL. >> >>2. If tx dim is supported, orphan mode may be removed and tx irq will be more >>reasonable. This provides good support for BQL. > >But when the device does not support dim, the orphan mode is still >needed, isn't it? Heng, is my assuption correct here? Thanks! > >> >>Thanks. >> >>> >>> Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxx> >>> --- >>> 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 >>> >>>
