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authorJames Bottomley <jejb@mulgrave.il.steeleye.com>2007-05-31 08:57:05 +0400
committerJames Bottomley <jejb@mulgrave.il.steeleye.com>2007-05-31 08:57:05 +0400
commit5bc65793cbf8da0d35f19ef025dda22887e79e80 (patch)
tree8291998abd73055de6f487fafa174ee2a5d3afee /net/ipv4/tcp_cong.c
parent6edae708bf77e012d855a7e2c7766f211d234f4f (diff)
parent3f0a6766e0cc5a577805732e5adb50a585c58175 (diff)
downloadlinux-5bc65793cbf8da0d35f19ef025dda22887e79e80.tar.xz
[SCSI] Merge up to linux-2.6 head
Conflicts: drivers/scsi/jazz_esp.c Same changes made by both SCSI and SPARC trees: problem with UTF-8 conversion in the copyright. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Diffstat (limited to 'net/ipv4/tcp_cong.c')
-rw-r--r--net/ipv4/tcp_cong.c40
1 files changed, 22 insertions, 18 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 86b26539e54b..1260e52ad772 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -276,30 +276,34 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
/*
- * Slow start (exponential increase) with
- * RFC3742 Limited Slow Start (fast linear increase) support.
+ * Slow start is used when congestion window is less than slow start
+ * threshold. This version implements the basic RFC2581 version
+ * and optionally supports:
+ * RFC3742 Limited Slow Start - growth limited to max_ssthresh
+ * RFC3465 Appropriate Byte Counting - growth limited by bytes acknowledged
*/
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
- * previously unacknowledged bytes ACKed by each incoming
- * acknowledgment, provided the increase is not more than L
- */
- if (tp->bytes_acked < tp->mss_cache)
- return;
- }
+ int cnt; /* increase in packets */
+
+ /* RFC3465: ABC Slow start
+ * Increase only after a full MSS of bytes is acked
+ *
+ * TCP sender SHOULD increase cwnd by the number of
+ * previously unacknowledged bytes ACKed by each incoming
+ * acknowledgment, provided the increase is not more than L
+ */
+ if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache)
+ return;
- if (sysctl_tcp_max_ssthresh > 0 &&
- tp->snd_cwnd > sysctl_tcp_max_ssthresh)
- cnt += sysctl_tcp_max_ssthresh>>1;
+ if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh)
+ cnt = sysctl_tcp_max_ssthresh >> 1; /* limited slow start */
else
- cnt += tp->snd_cwnd;
+ cnt = tp->snd_cwnd; /* exponential increase */
- /* RFC3465: We MAY increase by 2 if discovered delayed ack */
+ /* RFC3465: ABC
+ * 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;