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-rw-r--r--net/ipv4/tcp_scalable.c65
1 files changed, 65 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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+// SPDX-License-Identifier: GPL-2.0-only
+/* Tom Kelly's Scalable TCP
+ *
+ * See http://www.deneholme.net/tom/scalable/
+ *
+ * John Heffner <jheffner@sc.edu>
+ */
+
+#include <linux/module.h>
+#include <net/tcp.h>
+
+/* These factors derived from the recommended values in the aer:
+ * .01 and 7/8.
+ */
+#define TCP_SCALABLE_AI_CNT 100U
+#define TCP_SCALABLE_MD_SCALE 3
+
+static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (!tcp_is_cwnd_limited(sk))
+ return;
+
+ if (tcp_in_slow_start(tp)) {
+ acked = tcp_slow_start(tp, acked);
+ if (!acked)
+ return;
+ }
+ tcp_cong_avoid_ai(tp, min(tcp_snd_cwnd(tp), TCP_SCALABLE_AI_CNT),
+ acked);
+}
+
+static u32 tcp_scalable_ssthresh(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+
+ return max(tcp_snd_cwnd(tp) - (tcp_snd_cwnd(tp)>>TCP_SCALABLE_MD_SCALE), 2U);
+}
+
+static struct tcp_congestion_ops tcp_scalable __read_mostly = {
+ .ssthresh = tcp_scalable_ssthresh,
+ .undo_cwnd = tcp_reno_undo_cwnd,
+ .cong_avoid = tcp_scalable_cong_avoid,
+
+ .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");