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[DCCP] ccid3: Simplify control flow in the calculation of t_ipi

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This patch performs a simplifying (performance) optimisation:

 In each call of the inline function ccid3_calc_new_t_ipi(), the state is
 tested against TFRC_SSTATE_NO_FBACK. This is expensive when the function
 is called very often. A simpler solution, implemented by this patch, is
 to adapt the control flow.

Background:
This commit is contained in:
Gerrit Renker 2006-11-27 12:22:48 -02:00 • committed by David S. Miller
parent 90feeb951f
commit f5c2d6367b
1 changed files with 3 additions and 7 deletions
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10
net/dccp/ccids/ccid3.c
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@ -103,13 +103,7 @@ static void ccid3_hc_tx_set_state(struct sock *sk,
/* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */ /* 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) static inline void ccid3_calc_new_t_ipi(struct ccid3_hc_tx_sock *hctx)
{ {
/* hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_x);
* 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);
} }
/* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */ /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
@ -395,6 +389,8 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, int len)
"as a data packet", dccp_role(sk)); "as a data packet", dccp_role(sk));
return; return;
case TFRC_SSTATE_NO_FBACK: case TFRC_SSTATE_NO_FBACK:
/* t_nom, t_ipi, delta do not change until feedback arrives */
return;
case TFRC_SSTATE_FBACK: case TFRC_SSTATE_FBACK:
if (len > 0) { if (len > 0) {
timeval_sub_usecs(&hctx->ccid3hctx_t_nom, timeval_sub_usecs(&hctx->ccid3hctx_t_nom,