tcp: make TCP_RTO_MIN/MAX be tunable

tcp_rto_min,tcp_rto_max control the parameters of them. remember that the min value of tcp_rto_min is 4ms which be used to be div by RTO_MAX. Signed-off-by: Shan Wei <davidshan@tencent.com> Signed-off-by: Fuhai Wang <fuhaiwang@tencent.com> Signed-off-by: Xiaoming Gao <newtongao@tencent.com>
Tencent · Jan 2, 2020 · c715d50 · c715d50
1 parent 88885ab
commit c715d50
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Showing 4 changed files with 29 additions and 2 deletions.
diff --git a/include/net/tcp.h b/include/net/tcp.h
@@ -139,8 +139,8 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCP_DELACK_MIN	4U
 #define TCP_ATO_MIN	4U
 #endif
-#define TCP_RTO_MAX	((unsigned)(120*HZ))
-#define TCP_RTO_MIN	((unsigned)(HZ/5))
+#define TCP_RTO_MIN	((unsigned)((sysctl_tcp_rto_min*HZ)/1000))
+#define TCP_RTO_MAX	((unsigned)(sysctl_tcp_rto_max*HZ))
 #define TCP_TIMEOUT_MIN	(2U) /* Min timeout for TCP timers in jiffies */
 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ))	/* RFC6298 2.1 initial RTO value	*/
 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ))	/* RFC 1122 initial RTO value, now
@@ -276,6 +276,8 @@ extern int sysctl_tcp_pacing_ca_ratio;
 extern int sysctl_tcp_tw_ignore_syn_tsval_zero;
 extern int sysctl_tcp_loss_init_cwnd;
 extern int sysctl_tcp_init_cwnd;
+extern int sysctl_tcp_rto_min;
+extern int sysctl_tcp_rto_max;
 
 extern atomic_long_t tcp_memory_allocated;
 extern struct percpu_counter tcp_sockets_allocated;

diff --git a/include/uapi/linux/sysctl.h b/include/uapi/linux/sysctl.h
@@ -426,6 +426,8 @@ enum
 	NET_TCP_MAX_SSTHRESH=124,
 	NET_TCP_FRTO_RESPONSE=125,
 	NET_TCP_TW_IGNORE_SYN_TSVAL_ZERO=126,
+	NET_IPV4_TCP_RTO_MIN=127,
+	NET_IPV4_TCP_RTO_MAX=128,
 };
 
 enum {

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
@@ -756,6 +756,21 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname       = "tcp_rto_min",
+		.data           = &sysctl_tcp_rto_min,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec_minmax,
+		.extra1         = &four
+	},
+	{
+		.procname       = "tcp_rto_max",
+		.data           = &sysctl_tcp_rto_max,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec,
+	},
 	{ }
 };
 

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
@@ -24,6 +24,14 @@
 
 int sysctl_tcp_thin_linear_timeouts __read_mostly;
 
+/* default value is 200ms */
+int sysctl_tcp_rto_min __read_mostly = 200;
+EXPORT_SYMBOL(sysctl_tcp_rto_min);
+
+/* default value is 120s */
+int sysctl_tcp_rto_max __read_mostly = 120;
+EXPORT_SYMBOL(sysctl_tcp_rto_max);
+
 /**
  *  tcp_write_err() - close socket and save error info
  *  @sk:  The socket the error has appeared on.