hctx->ccid3hctx_state = state;
}
-/* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */
-static inline void ccid3_calc_new_t_ipi(struct ccid3_hc_tx_sock *hctx)
+/*
+ * Recalculate scheduled nominal send time t_nom, inter-packet interval
+ * t_ipi, and delta value. Should be called after each change to X.
+ */
+static inline void ccid3_update_send_time(struct ccid3_hc_tx_sock *hctx)
{
- /*
- * If no feedback spec says t_ipi is 1 second (set elsewhere and then
- * doubles after every no feedback timer (separate function)
- */
- if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
- hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s,
- hctx->ccid3hctx_x);
-}
+ timeval_sub_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
-/* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
-static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx)
-{
+ /* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */
+ hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_x);
+
+ /* Update nominal send time with regard to the new t_ipi */
+ timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
+
+ /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
TFRC_OPSYS_HALF_TIME_GRAN);
}
-
/*
* Update X by
* If (p > 0)
static void ccid3_hc_tx_update_x(struct sock *sk)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+ const __u32 old_x = hctx->ccid3hctx_x;
/* To avoid large error in calcX */
if (hctx->ccid3hctx_p >= TFRC_SMALLEST_P) {
hctx->ccid3hctx_t_ld = now;
}
}
+ if (hctx->ccid3hctx_x != old_x)
+ ccid3_update_send_time(hctx);
}
static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
- unsigned long next_tmout = 0;
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+ unsigned long next_tmout = USEC_PER_SEC / 5;
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later. */
/* XXX: set some sensible MIB */
- sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
- jiffies + HZ / 5);
- goto out;
+ goto restart_timer;
}
ccid3_pr_debug("%s, sk=%p, state=%s\n", dccp_role(sk), sk,
dccp_role(sk), sk,
ccid3_tx_state_name(hctx->ccid3hctx_state),
hctx->ccid3hctx_x);
- next_tmout = max_t(u32, 2 * usecs_div(hctx->ccid3hctx_s,
- hctx->ccid3hctx_x),
- TFRC_INITIAL_TIMEOUT);
- /*
- * FIXME - not sure above calculation is correct. See section
- * 5 of CCID3 11 should adjust tx_t_ipi and double that to
- * achieve it really
- */
+ /* The value of R is still undefined and so we can not recompute
+ * the timout value. Keep initial value as per [RFC 4342, 5]. */
+ next_tmout = TFRC_INITIAL_TIMEOUT;
+ ccid3_update_send_time(hctx);
break;
case TFRC_SSTATE_FBACK:
/*
}
/*
* 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);
goto out;
}
- sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
- jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout)));
hctx->ccid3hctx_idle = 1;
+
+restart_timer:
+ sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+ jiffies + usecs_to_jiffies(next_tmout));
out:
bh_unlock_sock(sk);
sock_put(sk);
}
+/*
+ * returns
+ * > 0: delay (in msecs) that should pass before actually sending
+ * = 0: can send immediately
+ * < 0: error condition; do not send packet
+ */
static int ccid3_hc_tx_send_packet(struct sock *sk,
struct sk_buff *skb, int len)
{
struct dccp_tx_hist_entry *new_packet;
struct timeval now;
long delay;
- int rc = -ENOTCONN;
BUG_ON(hctx == NULL);
- /* Check if pure ACK or Terminating*/
/*
- * XXX: We only call this function for DATA and DATAACK, on, these
- * packets can have zero length, but why the comment about "pure ACK"?
+ * This function is called only for Data and DataAck packets. Sending
+ * zero-sized Data(Ack)s is theoretically possible, but for congestion
+ * control this case is pathological - ignore it.
*/
if (unlikely(len == 0))
- goto out;
+ return -EBADMSG;
/* See if last packet allocated was not sent */
new_packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
new_packet = dccp_tx_hist_entry_new(ccid3_tx_hist,
SLAB_ATOMIC);
- rc = -ENOBUFS;
if (unlikely(new_packet == NULL)) {
DCCP_WARN("%s, sk=%p, not enough mem to add to history,"
"send refused\n", dccp_role(sk), sk);
- goto out;
+ return -ENOBUFS;
}
dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, new_packet);
hctx->ccid3hctx_last_win_count = 0;
hctx->ccid3hctx_t_last_win_count = now;
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
- hctx->ccid3hctx_t_ipi = TFRC_INITIAL_IPI;
- /* Set nominal send time for initial packet */
+ /* 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;
- timeval_add_usecs(&hctx->ccid3hctx_t_nom,
- hctx->ccid3hctx_t_ipi);
- ccid3_calc_new_delta(hctx);
- rc = 0;
break;
case TFRC_SSTATE_NO_FBACK:
case TFRC_SSTATE_FBACK:
- delay = (timeval_delta(&now, &hctx->ccid3hctx_t_nom) -
- hctx->ccid3hctx_delta);
- delay /= -1000;
- /* divide by -1000 is to convert to ms and get sign right */
- rc = delay > 0 ? delay : 0;
+ delay = timeval_delta(&hctx->ccid3hctx_t_nom, &now);
+ /*
+ * Scheduling of packet transmissions [RFC 3448, 4.6]
+ *
+ * if (t_now > t_nom - delta)
+ * // send the packet now
+ * else
+ * // send the packet in (t_nom - t_now) milliseconds.
+ */
+ if (delay >= hctx->ccid3hctx_delta)
+ return delay / 1000L;
break;
case TFRC_SSTATE_TERM:
DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
- rc = -EINVAL;
- break;
+ return -EINVAL;
}
- /* Can we send? if so add options and add to packet history */
- if (rc == 0) {
- dp->dccps_hc_tx_insert_options = 1;
- new_packet->dccphtx_ccval =
- DCCP_SKB_CB(skb)->dccpd_ccval =
- hctx->ccid3hctx_last_win_count;
- timeval_add_usecs(&hctx->ccid3hctx_t_nom,
- hctx->ccid3hctx_t_ipi);
- }
-out:
- return rc;
+ /* prepare to send now (add options etc.) */
+ dp->dccps_hc_tx_insert_options = 1;
+ new_packet->dccphtx_ccval = DCCP_SKB_CB(skb)->dccpd_ccval =
+ hctx->ccid3hctx_last_win_count;
+ timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
+
+ return 0;
}
static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, int len)
} else
ccid3_pr_debug("%s, sk=%p, seqno=%llu NOT inserted!\n",
dccp_role(sk), sk, dp->dccps_gss);
-
- switch (hctx->ccid3hctx_state) {
- case TFRC_SSTATE_NO_SENT:
- /* if first wasn't pure ack */
- if (len != 0)
- DCCP_CRIT("%s, First packet sent is noted "
- "as a data packet", dccp_role(sk));
- return;
- case TFRC_SSTATE_NO_FBACK:
- case TFRC_SSTATE_FBACK:
- if (len > 0) {
- timeval_sub_usecs(&hctx->ccid3hctx_t_nom,
- hctx->ccid3hctx_t_ipi);
- ccid3_calc_new_t_ipi(hctx);
- ccid3_calc_new_delta(hctx);
- timeval_add_usecs(&hctx->ccid3hctx_t_nom,
- hctx->ccid3hctx_t_ipi);
- }
- break;
- case TFRC_SSTATE_TERM:
- DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
- break;
- }
}
static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
pinv = opt_recv->ccid3or_loss_event_rate;
switch (hctx->ccid3hctx_state) {
- case TFRC_SSTATE_NO_SENT:
- /* FIXME: what to do here? */
- return;
case TFRC_SSTATE_NO_FBACK:
case TFRC_SSTATE_FBACK:
/* Calculate new round trip sample by
"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 */
/* unschedule no feedback timer */
sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
- /* Update sending rate */
+ /* Update sending rate (and likely t_ipi, t_nom, and delta) */
ccid3_hc_tx_update_x(sk);
- /* Update next send time */
- timeval_sub_usecs(&hctx->ccid3hctx_t_nom,
- hctx->ccid3hctx_t_ipi);
- ccid3_calc_new_t_ipi(hctx);
- timeval_add_usecs(&hctx->ccid3hctx_t_nom,
- hctx->ccid3hctx_t_ipi);
- ccid3_calc_new_delta(hctx);
-
/* remove all packets older than the one acked from history */
dccp_tx_hist_purge_older(ccid3_tx_hist,
&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",
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;
break;
- case TFRC_SSTATE_TERM:
- DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
+ case TFRC_SSTATE_NO_SENT:
+ DCCP_WARN("Illegal ACK received - no packet has been sent\n");
+ /* fall through */
+ case TFRC_SSTATE_TERM: /* ignore feedback when closing */
break;
}
}
/* 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);
projects / linux-2.6-block.git / blobdiff