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author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2006-11-27 20:32:37 -0200 |
---|---|---|
committer | David S. Miller <davem@sunset.davemloft.net> | 2006-12-02 21:30:52 -0800 |
commit | 5d0dbc4a9b2d325458dcbf9a8329bd1d2cc7bd7e (patch) | |
tree | 43aeec866470135e0b16420587ae04b7c41d43eb | |
parent | 17893bc1a632e195574dc0dd9751243f0d5993d2 (diff) | |
download | linux-5d0dbc4a9b2d325458dcbf9a8329bd1d2cc7bd7e.tar.gz linux-5d0dbc4a9b2d325458dcbf9a8329bd1d2cc7bd7e.tar.bz2 linux-5d0dbc4a9b2d325458dcbf9a8329bd1d2cc7bd7e.zip |
[DCCP] ccid3: Consolidate handling of t_RTO
This patch
* removes setting t_RTO in ccid3_hc_tx_init (per [RFC 3448, 4.2], t_RTO is
undefined until feedback has been received);
* makes some trivial changes (updates of comments);
* performs a small optimisation by exploiting that the feedback timeout
uses the value of t_ipi. The way it is done is safe, because the timeouts
appear after the changes to t_ipi, ensuring that up-to-date values are used;
* in ccid3_hc_tx_packet_recv, moves the t_rto statement closer to the calculation
of the next_tmout. This makes the code clearer to read and is also safe, since
t_rto is not updated until the next call of ccid3_hc_tx_packet_recv, and is not
read by the functions called via ccid_wait_for_ccid();
* removes a `max' statement in sk_reset_timer, this is not needed since the timeout
value is always greater than 1E6 microseconds.
* adds `XXX'es to highlight that currently the nofeedback timer is set
in a non-standard way
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
-rw-r--r-- | net/dccp/ccids/ccid3.c | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 4342caf53251..f0ed67c84a55 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -228,11 +228,10 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) } /* * Schedule no feedback timer to expire in - * max(4 * R, 2 * s / X) + * max(4 * t_RTO, 2 * s/X) = max(4 * t_RTO, 2 * t_ipi) + * XXX This is non-standard, RFC 3448, 4.3 uses 4 * R */ - next_tmout = max_t(u32, hctx->ccid3hctx_t_rto, - 2 * usecs_div(hctx->ccid3hctx_s, - hctx->ccid3hctx_x)); + next_tmout = max(hctx->ccid3hctx_t_rto, 2*hctx->ccid3hctx_t_ipi); break; case TFRC_SSTATE_NO_SENT: DCCP_BUG("Illegal %s state NO_SENT, sk=%p", dccp_role(sk), sk); @@ -460,10 +459,6 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) "r_sample=%us\n", dccp_role(sk), sk, hctx->ccid3hctx_rtt, r_sample); - /* Update timeout interval */ - hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt, - USEC_PER_SEC); - /* Update receive rate */ hctx->ccid3hctx_x_recv = x_recv;/* X_recv in bytes per sec */ @@ -491,17 +486,22 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) &hctx->ccid3hctx_hist, packet); /* * As we have calculated new ipi, delta, t_nom it is possible that - * we now can send a packet, so wake up dccp_wait_for_ccids. + * we now can send a packet, so wake up dccp_wait_for_ccid */ sk->sk_write_space(sk); + + /* Update timeout interval. We use the alternative variant of + * [RFC 3448, 3.1] which sets the upper bound of t_rto to one + * second, as it is suggested for TCP (see RFC 2988, 2.4). */ + hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt, + USEC_PER_SEC ); /* * Schedule no feedback timer to expire in - * max(4 * R, 2 * s / X) + * max(4 * t_RTO, 2 * s/X) = max(4 * t_RTO, 2 * t_ipi) + * XXX This is non-standard, RFC 3448, 4.3 uses 4 * R */ - next_tmout = max(hctx->ccid3hctx_t_rto, - 2 * usecs_div(hctx->ccid3hctx_s, - hctx->ccid3hctx_x)); + next_tmout = max(hctx->ccid3hctx_t_rto, 2*hctx->ccid3hctx_t_ipi); ccid3_pr_debug("%s, sk=%p, Scheduled no feedback timer to " "expire in %lu jiffies (%luus)\n", @@ -509,7 +509,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) usecs_to_jiffies(next_tmout), next_tmout); sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, - jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout))); + jiffies + usecs_to_jiffies(next_tmout)); /* set idle flag */ hctx->ccid3hctx_idle = 1; @@ -607,7 +607,6 @@ static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) /* Set transmission rate to 1 packet per second */ hctx->ccid3hctx_x = hctx->ccid3hctx_s; - hctx->ccid3hctx_t_rto = USEC_PER_SEC; hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT; INIT_LIST_HEAD(&hctx->ccid3hctx_hist); |