From 9bc8893937c8369c9c3a045c05f5820f2242bc96 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Sun, 22 Dec 2013 18:54:32 +0800 Subject: [PATCH] tun: Add support for RFS on tun flows This patch adds support so that the rps_flow_tables (RFS) can be programmed using the tun flows which are already set up to track flows for the purposes of queue selection. On the receive path (corresponding to select_queue and tun_net_xmit) the rxhash is saved in the flow_entry. The original code only does flow lookup in select_queue, so this patch adds a flow lookup in tun_net_xmit if num_queues == 1 (select_queue is not called from dev_queue_xmit->netdev_pick_tx in that case). The flow is recorded (processing CPU) in tun_flow_update (TX path), and reset when flow is deleted. Signed-off-by: Tom Herbert Signed-off-by: Zhi Yong Wu Signed-off-by: David S. Miller --- drivers/net/tun.c | 37 +++++++++++++++++++++++++++++++++++-- 1 file changed, 35 insertions(+), 2 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index a17a7018db19..3cf0457f5c69 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -152,6 +152,7 @@ struct tun_flow_entry { struct tun_struct *tun; u32 rxhash; + u32 rps_rxhash; int queue_index; unsigned long updated; }; @@ -220,6 +221,7 @@ static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun, rxhash, queue_index); e->updated = jiffies; e->rxhash = rxhash; + e->rps_rxhash = 0; e->queue_index = queue_index; e->tun = tun; hlist_add_head_rcu(&e->hash_link, head); @@ -232,6 +234,7 @@ static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e) { tun_debug(KERN_INFO, tun, "delete flow: hash %u index %u\n", e->rxhash, e->queue_index); + sock_rps_reset_flow_hash(e->rps_rxhash); hlist_del_rcu(&e->hash_link); kfree_rcu(e, rcu); --tun->flow_count; @@ -325,6 +328,7 @@ static void tun_flow_update(struct tun_struct *tun, u32 rxhash, /* TODO: keep queueing to old queue until it's empty? */ e->queue_index = queue_index; e->updated = jiffies; + sock_rps_record_flow_hash(e->rps_rxhash); } else { spin_lock_bh(&tun->lock); if (!tun_flow_find(head, rxhash) && @@ -341,6 +345,18 @@ unlock: rcu_read_unlock(); } +/** + * Save the hash received in the stack receive path and update the + * flow_hash table accordingly. + */ +static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash) +{ + if (unlikely(e->rps_rxhash != hash)) { + sock_rps_reset_flow_hash(e->rps_rxhash); + e->rps_rxhash = hash; + } +} + /* We try to identify a flow through its rxhash first. The reason that * we do not check rxq no. is because some cards(e.g 82599), chooses * the rxq based on the txq where the last packet of the flow comes. As @@ -361,9 +377,10 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb) txq = skb_get_hash(skb); if (txq) { e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq); - if (e) + if (e) { txq = e->queue_index; - else + tun_flow_save_rps_rxhash(e, txq); + } else /* use multiply and shift instead of expensive divide */ txq = ((u64)txq * numqueues) >> 32; } else if (likely(skb_rx_queue_recorded(skb))) { @@ -728,6 +745,22 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) if (txq >= tun->numqueues) goto drop; + if (tun->numqueues == 1) { + /* Select queue was not called for the skbuff, so we extract the + * RPS hash and save it into the flow_table here. + */ + __u32 rxhash; + + rxhash = skb_get_hash(skb); + if (rxhash) { + struct tun_flow_entry *e; + e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)], + rxhash); + if (e) + tun_flow_save_rps_rxhash(e, rxhash); + } + } + tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len); BUG_ON(!tfile);