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-rw-r--r--Documentation/networking/ip-sysctl.txt3
-rw-r--r--net/ipv4/tcp.c6
-rw-r--r--net/ipv4/tcp_output.c6
3 files changed, 5 insertions, 10 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index a46d78583ae1..7d8dc93fe2eb 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -588,9 +588,6 @@ 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 6e5617b9f9db..be5246e1d5b6 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -806,12 +806,6 @@ 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 d46f2143305c..10e12a61bb52 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1875,8 +1875,12 @@ 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);