Commit 17893bc1 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller

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

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: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@mandriva.com>
parent 48e03eee
...@@ -100,19 +100,24 @@ static void ccid3_hc_tx_set_state(struct sock *sk, ...@@ -100,19 +100,24 @@ static void ccid3_hc_tx_set_state(struct sock *sk,
hctx->ccid3hctx_state = state; 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)
{ {
timeval_sub_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
/* 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); hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_x);
}
/* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */ /* Update nominal send time with regard to the new t_ipi */
static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx) 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, hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
TFRC_OPSYS_HALF_TIME_GRAN); TFRC_OPSYS_HALF_TIME_GRAN);
} }
/* /*
* Update X by * Update X by
* If (p > 0) * If (p > 0)
...@@ -126,6 +131,7 @@ static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx) ...@@ -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) static void ccid3_hc_tx_update_x(struct sock *sk)
{ {
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(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 */ /* To avoid large error in calcX */
if (hctx->ccid3hctx_p >= TFRC_SMALLEST_P) { if (hctx->ccid3hctx_p >= TFRC_SMALLEST_P) {
...@@ -149,6 +155,8 @@ static void ccid3_hc_tx_update_x(struct sock *sk) ...@@ -149,6 +155,8 @@ static void ccid3_hc_tx_update_x(struct sock *sk)
hctx->ccid3hctx_t_ld = now; 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) 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) ...@@ -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 value of R is still undefined and so we can not recompute
* the timout value. Keep initial value as per [RFC 4342, 5]. */ * the timout value. Keep initial value as per [RFC 4342, 5]. */
next_tmout = TFRC_INITIAL_TIMEOUT; next_tmout = TFRC_INITIAL_TIMEOUT;
/* ccid3_update_send_time(hctx);
* 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
*/
break; break;
case TFRC_SSTATE_FBACK: case TFRC_SSTATE_FBACK:
/* /*
...@@ -479,17 +483,9 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) ...@@ -479,17 +483,9 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
/* unschedule no feedback timer */ /* unschedule no feedback timer */
sk_stop_timer(sk, &hctx->ccid3hctx_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); 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 */ /* remove all packets older than the one acked from history */
dccp_tx_hist_purge_older(ccid3_tx_hist, dccp_tx_hist_purge_older(ccid3_tx_hist,
&hctx->ccid3hctx_hist, packet); &hctx->ccid3hctx_hist, packet);
......
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