diff options
| -rw-r--r-- | net/ipv4/tcp_output.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 769a558159ee..e6b4fbd642f7 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1301,14 +1301,21 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, } tcp_header_size = tcp_options_size + sizeof(struct tcphdr); - /* if no packet is in qdisc/device queue, then allow XPS to select - * another queue. We can be called from tcp_tsq_handler() - * which holds one reference to sk. - * - * TODO: Ideally, in-flight pure ACK packets should not matter here. - * One way to get this would be to set skb->truesize = 2 on them. + /* We set skb->ooo_okay to one if this packet can select + * a different TX queue than prior packets of this flow, + * to avoid self inflicted reorders. + * The 'other' queue decision is based on current cpu number + * if XPS is enabled, or sk->sk_txhash otherwise. + * We can switch to another (and better) queue if: + * 1) No packet with payload is in qdisc/device queues. + * Delays in TX completion can defeat the test + * even if packets were already sent. + * 2) Or rtx queue is empty. + * This mitigates above case if ACK packets for + * all prior packets were already processed. */ - skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); + skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1) || + tcp_rtx_queue_empty(sk); /* If we had to use memory reserve to allocate this skb, * this might cause drops if packet is looped back : |