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| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2010-06-22 01:14:35 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-06-25 21:33:15 -0700 |
| commit | 59b80802a8a18b64d38b51aa168253684b2649d5 (patch) | |
| tree | b6be92f705d00796733e03e43041605b74d0ce5f /net/dccp/input.c | |
| parent | a7d13fbf85375698879d16f118af77fbfcc2de44 (diff) | |
| download | linux-59b80802a8a18b64d38b51aa168253684b2649d5.tar.gz linux-59b80802a8a18b64d38b51aa168253684b2649d5.tar.bz2 linux-59b80802a8a18b64d38b51aa168253684b2649d5.zip | |
dccp: make implementation of Syn-RTT symmetric
This patch is thanks to Andre Noll who reported the issue and helped testing.
The Syn-RTT sampled during the initial handshake currently only works for
the client sending the DCCP-Request. TFRC penalizes the absence of an RTT
sample with a very slow initial speed (1 packet per second), which delays
slow-start significantly, resulting in sluggish performance.
This patch mirrors the "Syn RTT" principle by adding a timestamp also onto
the DCCP-Response, producing an RTT sample when the (Data)Ack completing
the handshake arrives.
Also changed the documentation to 'TFRC' since Syn RTTs are also used by CCID-4.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/input.c')
| -rw-r--r-- | net/dccp/input.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/net/dccp/input.c b/net/dccp/input.c index 6beb6a7d6fba..10c957a88f4f 100644 --- a/net/dccp/input.c +++ b/net/dccp/input.c @@ -430,7 +430,7 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk, if (dccp_parse_options(sk, NULL, skb)) return 1; - /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */ + /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ if (likely(dp->dccps_options_received.dccpor_timestamp_echo)) dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp - dp->dccps_options_received.dccpor_timestamp_echo)); @@ -535,6 +535,8 @@ static int dccp_rcv_respond_partopen_state_process(struct sock *sk, const struct dccp_hdr *dh, const unsigned len) { + struct dccp_sock *dp = dccp_sk(sk); + u32 sample = dp->dccps_options_received.dccpor_timestamp_echo; int queued = 0; switch (dh->dccph_type) { @@ -559,7 +561,14 @@ static int dccp_rcv_respond_partopen_state_process(struct sock *sk, if (sk->sk_state == DCCP_PARTOPEN) inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); - dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; + /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ + if (likely(sample)) { + long delta = dccp_timestamp() - sample; + + dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta); + } + + dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; dccp_set_state(sk, DCCP_OPEN); if (dh->dccph_type == DCCP_PKT_DATAACK || |