diff options
| author |   Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2007-03-20 15:31:56 -0300 |
|---|---|---|
| committer |   David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:27:04 -0700 |
| commit | 30833ffead66e1f0052150a51db0b45151189ac1 (patch) | |
| tree | 2fcd4907a8d6295455c686e54aa6d02fa9533934 /net/dccp | |
| parent | [DCCP]: Sample RTT from SYN exchange (diff) | |
| download | linux-dev-30833ffead66e1f0052150a51db0b45151189ac1.tar.xz linux-dev-30833ffead66e1f0052150a51db0b45151189ac1.zip | |
[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>
Diffstat (limited to 'net/dccp')
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index f4097ddf2504..c3abd7695d55 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: |