* [PATCH 5/5] tun: Added support for RFS on tun flows
@ 2013-11-20 20:27 Tom Herbert
0 siblings, 0 replies; only message in thread
From: Tom Herbert @ 2013-11-20 20:27 UTC (permalink / raw)
To: davem; +Cc: netdev, edumazet, hkchu
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 <therbert@google.com>
---
drivers/net/tun.c | 47 ++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 44 insertions(+), 3 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index c3e20c4..81ba181 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 becuase some cards(e.g 82599), chooses
* the rxq based on the txq where the last packet of the flow comes. As
@@ -352,18 +368,26 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb)
{
struct tun_struct *tun = netdev_priv(dev);
struct tun_flow_entry *e;
- u32 txq = 0;
+ u32 txq = 0, rps_rxhash;
u32 numqueues = 0;
rcu_read_lock();
numqueues = ACCESS_ONCE(tun->numqueues);
+ /*
+ * Save the original rxhash from the skb. This may be a hash provided
+ * by the hardware. This should be the one used to program the rps_flow
+ * table.
+ */
+ rps_rxhash = skb_get_rxhash(skb);
+
txq = skb_get_sw_rxhash(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, rps_rxhash);
+ } else
/* use multiply and shift instead of expensive divide */
txq = ((u64)txq * numqueues) >> 32;
} else if (likely(skb_rx_queue_recorded(skb))) {
@@ -728,6 +752,23 @@ 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 rps_rxhash, rxhash;
+
+ rps_rxhash = skb_get_rxhash(skb);
+ rxhash = skb_get_sw_rxhash(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, rps_rxhash);
+ }
+ }
+
tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
BUG_ON(!tfile);
--
1.8.4.1
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2013-11-20 20:27 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-11-20 20:27 [PATCH 5/5] tun: Added support for RFS on tun flows Tom Herbert
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).