diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 3 | ||||
| -rw-r--r-- | net/ipv4/tcp.c | 6 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 6 |
3 files changed, 5 insertions, 10 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 3994f0bbeeb6..a59ee432a98f 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -571,9 +571,6 @@ tcp_limit_output_bytes - INTEGER typical pfifo_fast qdiscs. tcp_limit_output_bytes limits the number of bytes on qdisc or device to reduce artificial RTT/cwnd and reduce bufferbloat. - Note: For GSO/TSO enabled flows, we try to have at least two - packets in flight. Reducing tcp_limit_output_bytes might also - reduce the size of individual GSO packet (64KB being the max) Default: 131072 tcp_challenge_ack_limit - INTEGER diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index c888abf5a728..ae15c18df880 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -807,12 +807,6 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now, xmit_size_goal = min_t(u32, gso_size, sk->sk_gso_max_size - 1 - hlen); - /* TSQ : try to have at least two segments in flight - * (one in NIC TX ring, another in Qdisc) - */ - xmit_size_goal = min_t(u32, xmit_size_goal, - sysctl_tcp_limit_output_bytes >> 1); - xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal); /* We try hard to avoid divides here */ diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index cd16eb06bebf..e21be13f74a6 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1866,8 +1866,12 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, * - better RTT estimation and ACK scheduling * - faster recovery * - high rates + * Alas, some drivers / subsystems require a fair amount + * of queued bytes to ensure line rate. + * One example is wifi aggregation (802.11 AMPDU) */ - limit = max(skb->truesize, sk->sk_pacing_rate >> 10); + limit = max_t(unsigned int, sysctl_tcp_limit_output_bytes, + sk->sk_pacing_rate >> 10); if (atomic_read(&sk->sk_wmem_alloc) > limit) { set_bit(TSQ_THROTTLED, &tp->tsq_flags); |