From 52515e77a7a69867c479db4c9efb6be832b82179 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Mon, 17 Dec 2007 12:57:43 -0200 Subject: [PATCH] [CCID3]: Nofeedback timer according to rfc3448bis This implements the changes to the nofeedback timer handling suggested in draft rfc3448bis00, section 4.4. In particular, these changes mean: * better handling of the lossless case (p == 0) * the timestamp for computing t_ld becomes obsolete * much more recent document (RFC 3448 is almost 5 years old) * concepts in rfc3448bis arose from a real, working implementation (cf. sec. 12) Signed-off-by: Gerrit Renker Signed-off-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/dccp/ccids/ccid3.c | 63 +++++++++++++++++++----------------------- 1 file changed, 29 insertions(+), 34 deletions(-) diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 1156fef17471..d292f23c002e 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -131,12 +131,11 @@ static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now) * */ static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp) - { struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); __u64 min_rate = 2 * hctx->ccid3hctx_x_recv; const __u64 old_x = hctx->ccid3hctx_x; - ktime_t now = stamp? *stamp : ktime_get_real(); + ktime_t now = stamp ? *stamp : ktime_get_real(); /* * Handle IDLE periods: do not reduce below RFC3390 initial sending rate @@ -230,27 +229,27 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk, ccid3_tx_state_name(hctx->ccid3hctx_state)); - switch (hctx->ccid3hctx_state) { - case TFRC_SSTATE_NO_FBACK: - /* RFC 3448, 4.4: Halve send rate directly */ + if (hctx->ccid3hctx_state == TFRC_SSTATE_FBACK) + ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); + else if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK) + goto out; + + /* + * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4 + */ + if (hctx->ccid3hctx_t_rto == 0 || /* no feedback received yet */ + hctx->ccid3hctx_p == 0) { + + /* halve send rate directly */ hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2, (((__u64)hctx->ccid3hctx_s) << 6) / TFRC_T_MBI); - - ccid3_pr_debug("%s(%p, state=%s), updated tx rate to %u " - "bytes/s\n", dccp_role(sk), sk, - ccid3_tx_state_name(hctx->ccid3hctx_state), - (unsigned)(hctx->ccid3hctx_x >> 6)); - /* The value of R is still undefined and so we can not recompute - * the timeout value. Keep initial value as per [RFC 4342, 5]. */ - t_nfb = TFRC_INITIAL_TIMEOUT; ccid3_update_send_interval(hctx); - break; - case TFRC_SSTATE_FBACK: + } else { /* - * Modify the cached value of X_recv [RFC 3448, 4.4] + * Modify the cached value of X_recv * - * If (p == 0 || X_calc > 2 * X_recv) + * If (X_calc > 2 * X_recv) * X_recv = max(X_recv / 2, s / (2 * t_mbi)); * Else * X_recv = X_calc / 4; @@ -259,32 +258,28 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) */ BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc); - if (hctx->ccid3hctx_p == 0 || - (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))) { - + if (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5)) hctx->ccid3hctx_x_recv = max(hctx->ccid3hctx_x_recv / 2, (((__u64)hctx->ccid3hctx_s) << 6) / (2 * TFRC_T_MBI)); - } else { + else { hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc; hctx->ccid3hctx_x_recv <<= 4; } - /* Now recalculate X [RFC 3448, 4.3, step (4)] */ ccid3_hc_tx_update_x(sk, NULL); - /* - * Schedule no feedback timer to expire in - * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) - * See comments in packet_recv() regarding the value of t_RTO. - */ - t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi); - break; - case TFRC_SSTATE_NO_SENT: - DCCP_BUG("%s(%p) - Illegal state NO_SENT", dccp_role(sk), sk); - /* fall through */ - case TFRC_SSTATE_TERM: - goto out; } + ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n", + (unsigned long long)hctx->ccid3hctx_x); + + /* + * Set new timeout for the nofeedback timer. + * See comments in packet_recv() regarding the value of t_RTO. + */ + if (unlikely(hctx->ccid3hctx_t_rto == 0)) /* no feedback yet */ + t_nfb = TFRC_INITIAL_TIMEOUT; + else + t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi); restart_timer: sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, -- 2.20.1