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[DCCP] ccid3: Consistently update t_nom, t_ipi, t_delta

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This patch:

 * consolidates updating of parameters (t_nom, t_ipi, t_delta) which
   need to be updated at the same time, since they are inter-dependent

 * removes two inline functions which are no longer needed as a result of
   the above consolidation

 * resolves a FIXME regarding the re-calculation of t_ipi within the nofeedback
   timer, in the state where no feedback has previously been received

 * ties updating these parameters to updating the sending rate X, exploiting
   that all three parameters in turn depend on X; and using a small optimisation
   which can reduce the number of required instructions: only update the three
   parameters when X really changes

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>
This commit is contained in:
Gerrit Renker 2006-11-27 20:31:33 -02:00 committed by David S. Miller
parent 48e03eee71
commit 17893bc1a6
1 changed files with 18 additions and 22 deletions
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40
net/dccp/ccids/ccid3.c
View file

@ -100,19 +100,24 @@ static void ccid3_hc_tx_set_state(struct sock *sk,
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)
{
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)
@ -126,6 +131,7 @@ static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx)
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) {
@ -149,6 +155,8 @@ static void ccid3_hc_tx_update_x(struct sock *sk)
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)
@ -184,11 +192,7 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
/* 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;
/*
* 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
*/
ccid3_update_send_time(hctx);
break;
case TFRC_SSTATE_FBACK:
/*
@ -479,17 +483,9 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
/* 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);