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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2007-03-20 15:31:56 -0300
committerDavid S. Miller <davem@sunset.davemloft.net>2007-04-25 22:27:04 -0700
commit30833ffead66e1f0052150a51db0b45151189ac1 (patch)
tree2fcd4907a8d6295455c686e54aa6d02fa9533934
parent89560b53b92a07c529e13a462aa7fd87a844f1f5 (diff)
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[CCID3]: Use initial RTT sample from SYN exchange
The patch follows the following recommendation made in an erratum to RFC 4342: "Senders MAY additionally make use of other available RTT measurements, including those from the initial Request-Response packet exchange." It implements larger initial windows with regard to this inital RTT measurement, using the mechanism suggested in draft-ietf-dccp-rfc3448bis, section 4.2. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/dccp/ccids/ccid3.c31
1 files changed, 21 insertions, 10 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index f4097dd..c3abd76 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -334,19 +334,30 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
hctx->ccid3hctx_last_win_count = 0;
hctx->ccid3hctx_t_last_win_count = now;
- ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
-
- /* Set initial sending rate X/s to 1pps (X is scaled by 2^6) */
- hctx->ccid3hctx_x = hctx->ccid3hctx_s = skb->len;
- hctx->ccid3hctx_x <<= 6;
-
- /* First timeout, according to [RFC 3448, 4.2], is 1 second */
- hctx->ccid3hctx_t_ipi = USEC_PER_SEC;
- /* Initial delta: minimum of 0.5 sec and t_gran/2 */
- hctx->ccid3hctx_delta = TFRC_OPSYS_HALF_TIME_GRAN;
/* Set t_0 for initial packet */
hctx->ccid3hctx_t_nom = now;
+
+ hctx->ccid3hctx_s = skb->len;
+
+ /*
+ * Use initial RTT sample when available: recommended by erratum
+ * to RFC 4342. This implements the initialisation procedure of
+ * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
+ */
+ if (dp->dccps_syn_rtt) {
+ ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
+ hctx->ccid3hctx_rtt = dp->dccps_syn_rtt;
+ hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
+ hctx->ccid3hctx_t_ld = now;
+ } else {
+ /* Sender does not have RTT sample: X = MSS/second */
+ hctx->ccid3hctx_x = dp->dccps_mss_cache;
+ hctx->ccid3hctx_x <<= 6;
+ }
+ ccid3_update_send_interval(hctx);
+
+ ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
break;
case TFRC_SSTATE_NO_FBACK:
case TFRC_SSTATE_FBACK: