Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=886236c1247ab5e2ad9c73f6e9a652e3ae3c8b07
Commit: 886236c1247ab5e2ad9c73f6e9a652e3ae3c8b07
Parent: 5ef814753eb810d900fbd77af7c87f6d04f0e551
Author: John Heffner <[EMAIL PROTECTED]>
AuthorDate: Sun Mar 25 19:21:45 2007 -0700
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Wed Apr 25 22:23:19 2007 -0700
[TCP]: Add RFC3742 Limited Slow-Start, controlled by variable
sysctl_tcp_max_ssthresh.
Signed-off-by: John Heffner <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
include/linux/sysctl.h | 1 +
include/net/tcp.h | 1 +
net/ipv4/sysctl_net_ipv4.c | 8 ++++++++
net/ipv4/tcp_cong.c | 31 ++++++++++++++++++++++---------
4 files changed, 32 insertions(+), 9 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 9a8970b..98e0fd2 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -438,6 +438,7 @@ enum
NET_CIPSOV4_RBM_STRICTVALID=121,
NET_TCP_AVAIL_CONG_CONTROL=122,
NET_TCP_ALLOWED_CONG_CONTROL=123,
+ NET_TCP_MAX_SSTHRESH=124,
};
enum {
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 7fd6b77..6d09f50 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -230,6 +230,7 @@ extern int sysctl_tcp_mtu_probing;
extern int sysctl_tcp_base_mss;
extern int sysctl_tcp_workaround_signed_windows;
extern int sysctl_tcp_slow_start_after_idle;
+extern int sysctl_tcp_max_ssthresh;
extern atomic_t tcp_memory_allocated;
extern atomic_t tcp_sockets_allocated;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 0aa3047..d68effe 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -803,6 +803,14 @@ ctl_table ipv4_table[] = {
.proc_handler = &proc_allowed_congestion_control,
.strategy = &strategy_allowed_congestion_control,
},
+ {
+ .ctl_name = NET_TCP_MAX_SSTHRESH,
+ .procname = "tcp_max_ssthresh",
+ .data = &sysctl_tcp_max_ssthresh,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
{ .ctl_name = 0 }
};
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 34ae3f1..ccd8840 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -12,6 +12,8 @@
#include <linux/list.h>
#include <net/tcp.h>
+int sysctl_tcp_max_ssthresh = 0;
+
static DEFINE_SPINLOCK(tcp_cong_list_lock);
static LIST_HEAD(tcp_cong_list);
@@ -274,10 +276,13 @@ int tcp_set_congestion_control(struct sock *sk, const
char *name)
/*
- * Linear increase during slow start
+ * Slow start (exponential increase) with
+ * RFC3742 Limited Slow Start (fast linear increase) support.
*/
void tcp_slow_start(struct tcp_sock *tp)
{
+ int cnt = 0;
+
if (sysctl_tcp_abc) {
/* RFC3465: Slow Start
* TCP sender SHOULD increase cwnd by the number of
@@ -286,17 +291,25 @@ void tcp_slow_start(struct tcp_sock *tp)
*/
if (tp->bytes_acked < tp->mss_cache)
return;
-
- /* We MAY increase by 2 if discovered delayed ack */
- if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) {
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
- }
}
+
+ if (sysctl_tcp_max_ssthresh > 0 &&
+ tp->snd_cwnd > sysctl_tcp_max_ssthresh)
+ cnt += sysctl_tcp_max_ssthresh>>1;
+ else
+ cnt += tp->snd_cwnd;
+
+ /* RFC3465: We MAY increase by 2 if discovered delayed ack */
+ if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
+ cnt <<= 1;
tp->bytes_acked = 0;
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
+ tp->snd_cwnd_cnt += cnt;
+ while (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ tp->snd_cwnd_cnt -= tp->snd_cwnd;
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ }
}
EXPORT_SYMBOL_GPL(tcp_slow_start);
-
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