Add initial support for per-rx queue sysfs attributes to virtio-net. If mergeable packet buffers are enabled, adds a read-only mergeable packet buffer size sysfs attribute for each RX queue.
Signed-off-by: Michael Dalton <[email protected]> --- drivers/net/virtio_net.c | 66 +++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 62 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 3e82311..f315cbb 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -27,6 +27,7 @@ #include <linux/slab.h> #include <linux/cpu.h> #include <linux/average.h> +#include <linux/seqlock.h> static int napi_weight = NAPI_POLL_WEIGHT; module_param(napi_weight, int, 0444); @@ -89,6 +90,12 @@ struct receive_queue { /* Average packet length for mergeable receive buffers. */ struct ewma mrg_avg_pkt_len; + /* Sequence counter to allow sysfs readers to safely access stats. + * Assumes a single virtio-net writer, which is enforced by virtio-net + * and NAPI. + */ + seqcount_t sysfs_seq; + /* Page frag for packet buffer allocation. */ struct page_frag alloc_frag; @@ -416,7 +423,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, } } + write_seqcount_begin(&rq->sysfs_seq); ewma_add(&rq->mrg_avg_pkt_len, head_skb->len); + write_seqcount_end(&rq->sysfs_seq); return head_skb; err_skb: @@ -604,18 +613,29 @@ static int add_recvbuf_big(struct receive_queue *rq, gfp_t gfp) return err; } -static int add_recvbuf_mergeable(struct receive_queue *rq, gfp_t gfp) +static unsigned int get_mergeable_buf_len(struct ewma *avg_pkt_len) { const size_t hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf); + unsigned int len; + + len = hdr_len + clamp_t(unsigned int, ewma_read(avg_pkt_len), + GOOD_PACKET_LEN, PAGE_SIZE - hdr_len); + return ALIGN(len, MERGEABLE_BUFFER_ALIGN); +} + +static int add_recvbuf_mergeable(struct receive_queue *rq, gfp_t gfp) +{ struct page_frag *alloc_frag = &rq->alloc_frag; char *buf; unsigned long ctx; int err; unsigned int len, hole; - len = hdr_len + clamp_t(unsigned int, ewma_read(&rq->mrg_avg_pkt_len), - GOOD_PACKET_LEN, PAGE_SIZE - hdr_len); - len = ALIGN(len, MERGEABLE_BUFFER_ALIGN); + /* avg_pkt_len is written only in NAPI rx softirq context. We may + * read avg_pkt_len without using the sysfs_seq seqcount, as this code + * is called only in NAPI rx softirq context or when NAPI is disabled. + */ + len = get_mergeable_buf_len(&rq->mrg_avg_pkt_len); if (unlikely(!skb_page_frag_refill(len, alloc_frag, gfp))) return -ENOMEM; @@ -1557,6 +1577,7 @@ static int virtnet_alloc_queues(struct virtnet_info *vi) napi_weight); sg_init_table(vi->rq[i].sg, ARRAY_SIZE(vi->rq[i].sg)); + seqcount_init(&vi->rq[i].sysfs_seq); ewma_init(&vi->rq[i].mrg_avg_pkt_len, 1, RECEIVE_AVG_WEIGHT); sg_init_table(vi->sq[i].sg, ARRAY_SIZE(vi->sq[i].sg)); } @@ -1594,6 +1615,39 @@ err: return ret; } +#ifdef CONFIG_SYSFS +static ssize_t mergeable_rx_buffer_size_show(struct netdev_rx_queue *queue, + struct rx_queue_attribute *attribute, char *buf) +{ + struct virtnet_info *vi = netdev_priv(queue->dev); + unsigned int queue_index = get_netdev_rx_queue_index(queue); + struct receive_queue *rq; + struct ewma avg; + unsigned int start; + + BUG_ON(queue_index >= vi->max_queue_pairs); + rq = &vi->rq[queue_index]; + do { + start = read_seqcount_begin(&rq->sysfs_seq); + avg = rq->mrg_avg_pkt_len; + } while (read_seqcount_retry(&rq->sysfs_seq, start)); + return sprintf(buf, "%u\n", get_mergeable_buf_len(&avg)); +} + +static struct rx_queue_attribute mergeable_rx_buffer_size_attribute = + __ATTR_RO(mergeable_rx_buffer_size); + +static struct attribute *virtio_net_mrg_rx_attrs[] = { + &mergeable_rx_buffer_size_attribute.attr, + NULL +}; + +static const struct attribute_group virtio_net_mrg_rx_group = { + .name = "virtio_net", + .attrs = virtio_net_mrg_rx_attrs +}; +#endif + static int virtnet_probe(struct virtio_device *vdev) { int i, err; @@ -1708,6 +1762,10 @@ static int virtnet_probe(struct virtio_device *vdev) if (err) goto free_stats; +#ifdef CONFIG_SYSFS + if (vi->mergeable_rx_bufs) + dev->sysfs_rx_queue_group = &virtio_net_mrg_rx_group; +#endif netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs); netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs); -- 1.8.5.2 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
