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-rw-r--r--net/ipv4/tcp_scalable.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/net/ipv4/tcp_scalable.c b/net/ipv4/tcp_scalable.c
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+++ b/net/ipv4/tcp_scalable.c
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+/* Tom Kelly's Scalable TCP
+ *
+ * See htt://www-lce.eng.cam.ac.uk/~ctk21/scalable/
+ *
+ * John Heffner <jheffner@sc.edu>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <net/tcp.h>
+
+/* These factors derived from the recommended values in the aer:
+ * .01 and and 7/8. We use 50 instead of 100 to account for
+ * delayed ack.
+ */
+#define TCP_SCALABLE_AI_CNT 50U
+#define TCP_SCALABLE_MD_SCALE 3
+
+static void tcp_scalable_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
+ u32 in_flight, int flag)
+{
+ if (in_flight < tp->snd_cwnd)
+ return;
+
+ if (tp->snd_cwnd <= tp->snd_ssthresh) {
+ tp->snd_cwnd++;
+ } else {
+ tp->snd_cwnd_cnt++;
+ if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ }
+ }
+ tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
+ tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+static u32 tcp_scalable_ssthresh(struct tcp_sock *tp)
+{
+ return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
+}
+
+
+static struct tcp_congestion_ops tcp_scalable = {
+ .ssthresh = tcp_scalable_ssthresh,
+ .cong_avoid = tcp_scalable_cong_avoid,
+ .min_cwnd = tcp_reno_min_cwnd,
+
+ .owner = THIS_MODULE,
+ .name = "scalable",
+};
+
+static int __init tcp_scalable_register(void)
+{
+ return tcp_register_congestion_control(&tcp_scalable);
+}
+
+static void __exit tcp_scalable_unregister(void)
+{
+ tcp_unregister_congestion_control(&tcp_scalable);
+}
+
+module_init(tcp_scalable_register);
+module_exit(tcp_scalable_unregister);
+
+MODULE_AUTHOR("John Heffner");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Scalable TCP");