/*-
* Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce at minimum a disclaimer
* similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
* redistribution must be conditioned upon including a substantially
* similar Disclaimer requirement for further binary redistribution.
* 3. Neither the names of the above-listed copyright holders nor the names
* of any contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* NO WARRANTY
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGES.
*/
#ifdef ONOE_DEBUG
enum {
ATH_DEBUG_RATE = 0x00000010, /* rate control */
};
#define DPRINTF(sc, _fmt, ...) do { \
if (sc->sc_debug & ATH_DEBUG_RATE) \
printf(_fmt, __VA_ARGS__); \
} while (0)
#else
#define DPRINTF(sc, _fmt, ...)
#endif
/*
* Default parameters for the rate control algorithm. These are
* all tunable with sysctls. The rate controller runs periodically
* (each ath_rateinterval ms) analyzing transmit statistics for each
* neighbor/station (when operating in station mode this is only the AP).
* If transmits look to be working well over a sampling period then
* it gives a "raise rate credit". If transmits look to not be working
* well than it deducts a credit. If the credits cross a threshold then
* the transmit rate is raised. Various error conditions force the
* the transmit rate to be dropped.
*
* The decision to issue/deduct a credit is based on the errors and
* retries accumulated over the sampling period. ath_rate_raise defines
* the percent of retransmits for which a credit is issued/deducted.
* ath_rate_raise_threshold defines the threshold on credits at which
* the transmit rate is increased.
*
* XXX this algorithm is flawed.
*/
static int ath_rateinterval = 1000; /* rate ctl interval (ms) */
static int ath_rate_raise = 10; /* add credit threshold */
static int ath_rate_raise_threshold = 10; /* rate ctl raise threshold */
KASSERTMSG(rt != NULL, "no rate table, mode %u", sc->sc_curmode);
DPRINTF(sc, "%s: set xmit rate for %s to %dM\n",
__func__, ether_sprintf(ni->ni_macaddr),
ni->ni_rates.rs_nrates > 0 ?
(ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL) / 2 : 0);
ni->ni_txrate = rate;
/*
* Before associating a node has no rate set setup
* so we can't calculate any transmit codes to use.
* This is ok since we should never be sending anything
* but management frames and those always go at the
* lowest hardware rate.
*/
if (ni->ni_rates.rs_nrates == 0)
goto done;
on->on_tx_rix0 = sc->sc_rixmap[
ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL];
on->on_tx_rate0 = rt->info[on->on_tx_rix0].rateCode;
on->on_tx_rate0sp = on->on_tx_rate0 |
rt->info[on->on_tx_rix0].shortPreamble;
if (sc->sc_mrretry) {
/*
* Hardware supports multi-rate retry; setup two
* step-down retry rates and make the lowest rate
* be the ``last chance''. We use 4, 2, 2, 2 tries
* respectively (4 is set here, the rest are fixed
* in the xmit routine).
*/
on->on_tx_try0 = 1 + 3; /* 4 tries at rate 0 */
if (--rate >= 0) {
rix = sc->sc_rixmap[
ni->ni_rates.rs_rates[rate]&IEEE80211_RATE_VAL];
on->on_tx_rate1 = rt->info[rix].rateCode;
on->on_tx_rate1sp = on->on_tx_rate1 |
rt->info[rix].shortPreamble;
} else {
on->on_tx_rate1 = on->on_tx_rate1sp = 0;
}
if (--rate >= 0) {
rix = sc->sc_rixmap[
ni->ni_rates.rs_rates[rate]&IEEE80211_RATE_VAL];
on->on_tx_rate2 = rt->info[rix].rateCode;
on->on_tx_rate2sp = on->on_tx_rate2 |
rt->info[rix].shortPreamble;
} else {
on->on_tx_rate2 = on->on_tx_rate2sp = 0;
}
if (rate > 0) {
/* NB: only do this if we didn't already do it above */
on->on_tx_rate3 = rt->info[0].rateCode;
on->on_tx_rate3sp =
on->on_tx_rate3 | rt->info[0].shortPreamble;
} else {
on->on_tx_rate3 = on->on_tx_rate3sp = 0;
}
} else {
on->on_tx_try0 = ATH_TXMAXTRY; /* max tries at rate 0 */
on->on_tx_rate1 = on->on_tx_rate1sp = 0;
on->on_tx_rate2 = on->on_tx_rate2sp = 0;
on->on_tx_rate3 = on->on_tx_rate3sp = 0;
}
done:
on->on_tx_ok = on->on_tx_err = on->on_tx_retr = on->on_tx_upper = 0;
}
/*
* Set the starting transmit rate for a node.
*/
static void
ath_rate_ctl_start(struct ath_softc *sc, struct ieee80211_node *ni)
{
#define RATE(_ix) (ni->ni_rates.rs_rates[(_ix)] & IEEE80211_RATE_VAL)
struct ieee80211com *ic = &sc->sc_ic;
int srate;
KASSERTMSG(ni->ni_rates.rs_nrates > 0, "no rates");
if (ic->ic_fixed_rate == IEEE80211_FIXED_RATE_NONE) {
/*
* No fixed rate is requested. For 11b start with
* the highest negotiated rate; otherwise, for 11g
* and 11a, we start "in the middle" at 24Mb or 36Mb.
*/
srate = ni->ni_rates.rs_nrates - 1;
if (sc->sc_curmode != IEEE80211_MODE_11B) {
/*
* Scan the negotiated rate set to find the
* closest rate.
*/
/* NB: the rate set is assumed sorted */
for (; srate >= 0 && RATE(srate) > 72; srate--)
;
KASSERTMSG(srate >= 0, "bogus rate set");
}
} else {
/*
* A fixed rate is to be used; ic_fixed_rate is an
* index into the supported rate set. Convert this
* to the index into the negotiated rate set for
* the node. We know the rate is there because the
* rate set is checked when the station associates.
*/
const struct ieee80211_rateset *rs =
&ic->ic_sup_rates[ic->ic_curmode];
int r = rs->rs_rates[ic->ic_fixed_rate] & IEEE80211_RATE_VAL;
/* NB: the rate set is assumed sorted */
srate = ni->ni_rates.rs_nrates - 1;
for (; srate >= 0 && RATE(srate) != r; srate--)
;
KASSERTMSG(srate >= 0,
"fixed rate %d not in rate set", ic->ic_fixed_rate);
}
ath_rate_update(sc, ni, srate);
#undef RATE
}
/*
* Reset the rate control state for each 802.11 state transition.
*/
void
ath_rate_newstate(struct ath_softc *sc, enum ieee80211_state state)
{
struct onoe_softc *osc = (struct onoe_softc *) sc->sc_rc;
struct ieee80211com *ic = &sc->sc_ic;
struct ieee80211_node *ni;
if (state == IEEE80211_S_INIT) {
callout_stop(&osc->timer);
return;
}
if (ic->ic_opmode == IEEE80211_M_STA) {
/*
* Reset local xmit state; this is really only
* meaningful when operating in station mode.
*/
ni = ic->ic_bss;
if (state == IEEE80211_S_RUN) {
ath_rate_ctl_start(sc, ni);
} else {
ath_rate_update(sc, ni, 0);
}
} else {
/*
* When operating as a station the node table holds
* the AP's that were discovered during scanning.
* For any other operating mode we want to reset the
* tx rate state of each node.
*/
ieee80211_iterate_nodes(&ic->ic_sta, ath_rate_cb, sc);
ath_rate_update(sc, ic->ic_bss, 0);
}
if (ic->ic_fixed_rate == IEEE80211_FIXED_RATE_NONE &&
state == IEEE80211_S_RUN) {
int interval;
/*
* Start the background rate control thread if we
* are not configured to use a fixed xmit rate.
*/
interval = ath_rateinterval;
if (ic->ic_opmode == IEEE80211_M_STA)
interval /= 2;
callout_reset(&osc->timer, (interval * hz) / 1000,
ath_ratectl, &sc->sc_if);
}
}
/*
* Examine and potentially adjust the transmit rate.
*/
static void
ath_rate_ctl(void *arg, struct ieee80211_node *ni)
{
struct ath_softc *sc = arg;
struct onoe_node *on = ATH_NODE_ONOE(ATH_NODE(ni));
struct ieee80211_rateset *rs = &ni->ni_rates;
int dir = 0, nrate, enough;
/*
* Rate control
* XXX: very primitive version.
*/
enough = (on->on_tx_ok + on->on_tx_err >= 10);
/* no packet reached -> down */
if (on->on_tx_err > 0 && on->on_tx_ok == 0)
dir = -1;
/* all packets needs retry in average -> down */
if (enough && on->on_tx_ok < on->on_tx_retr)
dir = -1;
/* no error and less than rate_raise% of packets need retry -> up */
if (enough && on->on_tx_err == 0 &&
on->on_tx_retr < (on->on_tx_ok * ath_rate_raise) / 100)
dir = 1;
DPRINTF(sc, "%s: ok %d err %d retr %d upper %d dir %d\n",
ether_sprintf(ni->ni_macaddr),
on->on_tx_ok, on->on_tx_err, on->on_tx_retr,
on->on_tx_upper, dir);
nrate = ni->ni_txrate;
switch (dir) {
case 0:
if (enough && on->on_tx_upper > 0)
on->on_tx_upper--;
break;
case -1:
if (nrate > 0) {
nrate--;
sc->sc_stats.ast_rate_drop++;
}
on->on_tx_upper = 0;
break;
case 1:
/* raise rate if we hit rate_raise_threshold */
if (++on->on_tx_upper < ath_rate_raise_threshold)
break;
on->on_tx_upper = 0;
if (nrate + 1 < rs->rs_nrates) {
nrate++;
sc->sc_stats.ast_rate_raise++;
}
break;
}
