Commit 3853b584 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

xps: Improvements in TX queue selection 



In dev_pick_tx, don't do work in calculating queue
index or setting
the index in the sock unless the device has more than one queue.  This
allows the sock to be set only with a queue index of a multi-queue
device which is desirable if device are stacked like in a tunnel.

We also allow the mapping of a socket to queue to be changed.  To
maintain in order packet transmission a flag (ooo_okay) has been
added to the sk_buff structure.  If a transport layer sets this flag
on a packet, the transmit queue can be changed for the socket.
Presumably, the transport would set this if there was no possbility
of creating OOO packets (for instance, there are no packets in flight
for the socket).  This patch includes the modification in TCP output
for setting this flag.

Signed-off-by: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 22f4fbd9

include/linux/skbuff.h

+2 −1
Original line number Diff line number Diff line
@@ -386,9 +386,10 @@ struct sk_buff { 
#else

	__u8			deliver_no_wcard:1;

#endif

	__u8			ooo_okay:1;

	kmemcheck_bitfield_end(flags2);



	/* 0/14 bit hole */

	/* 0/13 bit hole */



#ifdef CONFIG_NET_DMA

	dma_cookie_t		dma_cookie;

net/core/dev.c

+11 −7
Original line number Diff line number Diff line
@@ -2148,20 +2148,24 @@ static struct netdev_queue *dev_pick_tx(struct net_device *dev, 
	int queue_index;

	const struct net_device_ops *ops = dev->netdev_ops;



	if (ops->ndo_select_queue) {

	if (dev->real_num_tx_queues == 1)

		queue_index = 0;

	else if (ops->ndo_select_queue) {

		queue_index = ops->ndo_select_queue(dev, skb);

		queue_index = dev_cap_txqueue(dev, queue_index);

	} else {

		struct sock *sk = skb->sk;

		queue_index = sk_tx_queue_get(sk);

		if (queue_index < 0 || queue_index >= dev->real_num_tx_queues) {



			queue_index = 0;

			if (dev->real_num_tx_queues > 1)

		if (queue_index < 0 || skb->ooo_okay ||

		    queue_index >= dev->real_num_tx_queues) {

			int old_index = queue_index;



			queue_index = skb_tx_hash(dev, skb);



			if (sk) {

				struct dst_entry *dst = rcu_dereference_check(sk->sk_dst_cache, 1);

			if (queue_index != old_index && sk) {

				struct dst_entry *dst =

				    rcu_dereference_check(sk->sk_dst_cache, 1);



				if (dst && skb_dst(skb) == dst)

					sk_tx_queue_set(sk, queue_index);

net/ipv4/tcp_output.c

+4 −1
Original line number Diff line number Diff line
@@ -822,8 +822,11 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 
							   &md5);

	tcp_header_size = tcp_options_size + sizeof(struct tcphdr);



	if (tcp_packets_in_flight(tp) == 0)

	if (tcp_packets_in_flight(tp) == 0) {

		tcp_ca_event(sk, CA_EVENT_TX_START);

		skb->ooo_okay = 1;

	} else

		skb->ooo_okay = 0;



	skb_push(skb, tcp_header_size);

	skb_reset_transport_header(skb);

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