return err;
}
+/* RFC2861 Check whether we are limited by application or congestion window
+ * This is the inverse of cwnd check in tcp_tso_should_defer
+ */
+int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ u32 left;
+
+ if (in_flight >= tp->snd_cwnd)
+ return 1;
+
+ if (!sk_can_gso(sk))
+ return 0;
+
+ left = tp->snd_cwnd - in_flight;
+ if (sysctl_tcp_tso_win_divisor)
+ return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd;
+ else
+ return left <= tcp_max_burst(tp);
+}
+EXPORT_SYMBOL_GPL(tcp_is_cwnd_limited);
/*
- * Slow start (exponential increase) with
- * RFC3742 Limited Slow Start (fast linear increase) support.
+ * Slow start is used when congestion window is less than slow start
+ * threshold. This version implements the basic RFC2581 version
+ * and optionally supports:
+ * RFC3742 Limited Slow Start - growth limited to max_ssthresh
+ * RFC3465 Appropriate Byte Counting - growth limited by bytes acknowledged
*/
void tcp_slow_start(struct tcp_sock *tp)
{
- int cnt = 0;
-
- if (sysctl_tcp_abc) {
- /* RFC3465: Slow Start
- * TCP sender SHOULD increase cwnd by the number of
- * previously unacknowledged bytes ACKed by each incoming
- * acknowledgment, provided the increase is not more than L
- */
- if (tp->bytes_acked < tp->mss_cache)
- return;
- }
+ int cnt; /* increase in packets */
+
+ /* RFC3465: ABC Slow start
+ * Increase only after a full MSS of bytes is acked
+ *
+ * TCP sender SHOULD increase cwnd by the number of
+ * previously unacknowledged bytes ACKed by each incoming
+ * acknowledgment, provided the increase is not more than L
+ */
+ if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache)
+ return;
- if (sysctl_tcp_max_ssthresh > 0 &&
- tp->snd_cwnd > sysctl_tcp_max_ssthresh)
- cnt += sysctl_tcp_max_ssthresh>>1;
+ if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh)
+ cnt = sysctl_tcp_max_ssthresh >> 1; /* limited slow start */
else
- cnt += tp->snd_cwnd;
+ cnt = tp->snd_cwnd; /* exponential increase */
- /* RFC3465: We MAY increase by 2 if discovered delayed ack */
+ /* RFC3465: ABC
+ * We MAY increase by 2 if discovered delayed ack
+ */
if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
cnt <<= 1;
tp->bytes_acked = 0;
/* This is Jacobson's slow start and congestion avoidance.
* SIGCOMM '88, p. 328.
*/
-void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight,
- int flag)
+void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
{
struct tcp_sock *tp = tcp_sk(sk);