svn commit: r362854 - stable/12/sys/netinet/cc

[Michael Tuexen]

Author: tuexen
Date: Wed Jul  1 19:23:15 2020
New Revision: 362854
URL: https://svnweb.freebsd.org/changeset/base/362854

Log:
  MFC r354772: Implement a TCP CUBIC-specific after idle reaction.
  This patch addresses a very common case of frequent application stalls,
  where TCP runs idle and looses the state of the network.
  
  Submitted by:		rscheff
  Reviewed by:		Cheng Cui
  Differential Revision:	https://reviews.freebsd.org/D18954

Modified:
  stable/12/sys/netinet/cc/cc_cubic.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/netinet/cc/cc_cubic.c
==============================================================================
--- stable/12/sys/netinet/cc/cc_cubic.c	Wed Jul  1 19:15:43 2020	(r362853)
+++ stable/12/sys/netinet/cc/cc_cubic.c	Wed Jul  1 19:23:15 2020	(r362854)
@@ -78,6 +78,7 @@ static int	cubic_mod_init(void);
 static void	cubic_post_recovery(struct cc_var *ccv);
 static void	cubic_record_rtt(struct cc_var *ccv);
 static void	cubic_ssthresh_update(struct cc_var *ccv);
+static void	cubic_after_idle(struct cc_var *ccv);
 
 struct cubic {
 	/* Cubic K in fixed point form with CUBIC_SHIFT worth of precision. */
@@ -115,6 +116,7 @@ struct cc_algo cubic_cc_algo = {
 	.conn_init = cubic_conn_init,
 	.mod_init = cubic_mod_init,
 	.post_recovery = cubic_post_recovery,
+	.after_idle = cubic_after_idle,
 };
 
 static void
@@ -206,7 +208,24 @@ cubic_ack_received(struct cc_var *ccv, uint16_t type)
 	}
 }
 
+/*
+ * This is a Cubic specific implementation of after_idle.
+ *   - Reset cwnd by calling New Reno implementation of after_idle.
+ *   - Reset t_last_cong.
+ */
 static void
+cubic_after_idle(struct cc_var *ccv)
+{
+	struct cubic *cubic_data;
+
+	cubic_data = ccv->cc_data;
+
+	newreno_cc_algo.after_idle(ccv);
+	cubic_data->t_last_cong = ticks;
+}
+
+
+static void
 cubic_cb_destroy(struct cc_var *ccv)
 {
 	free(ccv->cc_data, M_CUBIC);
@@ -303,9 +322,6 @@ cubic_conn_init(struct cc_var *ccv)
 static int
 cubic_mod_init(void)
 {
-
-	cubic_cc_algo.after_idle = newreno_cc_algo.after_idle;
-
 	return (0);
 }