* John Heffner <jheffner@psc.edu>
*/
-#include <linux/config.h>
#include <linux/module.h>
#include <net/tcp.h>
u32 ai;
};
+static int max_ssthresh = 100;
+module_param(max_ssthresh, int, 0644);
+MODULE_PARM_DESC(max_ssthresh, "limited slow start threshold (RFC3742)");
+
static void hstcp_init(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
- if (tp->snd_cwnd <= tp->snd_ssthresh)
- tcp_slow_start(tp);
- else {
- /* Update AIMD parameters */
+ if (tp->snd_cwnd <= tp->snd_ssthresh) {
+ /* RFC3742: limited slow start
+ * the window is increased by 1/K MSS for each arriving ACK,
+ * for K = int(cwnd/(0.5 max_ssthresh))
+ */
+ if (max_ssthresh > 0 && tp->snd_cwnd > max_ssthresh) {
+ u32 k = max(tp->snd_cwnd / (max_ssthresh >> 1), 1U);
+ if (++tp->snd_cwnd_cnt >= k) {
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ }
+ } else {
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ }
+ } else {
+ /* Update AIMD parameters.
+ *
+ * We want to guarantee that:
+ * hstcp_aimd_vals[ca->ai-1].cwnd <
+ * snd_cwnd <=
+ * hstcp_aimd_vals[ca->ai].cwnd
+ */
if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
ca->ai < HSTCP_AIMD_MAX - 1)
ca->ai++;
- } else if (tp->snd_cwnd < hstcp_aimd_vals[ca->ai].cwnd) {
- while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
- ca->ai > 0)
+ } else if (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd) {
+ while (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd)
ca->ai--;
}
static int __init hstcp_register(void)
{
- BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
+ BUILD_BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
return tcp_register_congestion_control(&tcp_highspeed);
}