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Date: Mon, 17 Dec 2007 13:00:18 -0200
From: Arnaldo Carvalho de Melo <acme@...hat.com>
To: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org, dccp@...r.kernel.org,
Gerrit Renker <gerrit@....abdn.ac.uk>,
Ian McDonald <ian.mcdonald@...di.co.nz>,
Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 4/5] [CCID3]: Nofeedback timer according to rfc3448bis
From: Gerrit Renker <gerrit@....abdn.ac.uk>
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 <gerrit@....abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@...di.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
net/dccp/ccids/ccid3.c | 63 ++++++++++++++++++++++--------------------------
1 files changed, 29 insertions(+), 34 deletions(-)
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 7c8e9ad..00b5f11 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 timout 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,
--
1.5.3.6
--
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