ath_rate/onoe/onoe.c

/*-
 * Copyright (c) 2002-2007 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.
 *
 * 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/dev/ath/ath_rate/onoe/onoe.c 186804 2009-01-06 01:36:36Z sam $");

/*
 * Atsushi Onoe's rate control algorithm.
 */
#include "opt_inet.h"
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/errno.h>

#include <machine/bus.h>
#include <machine/resource.h>
#include <sys/bus.h>

#include <sys/socket.h>

#include <net/if.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/ethernet.h>		/* XXX for ether_sprintf */

#include <net80211/ieee80211_var.h>

#include <net/bpf.h>

#ifdef INET
#include <netinet/in.h>
#include <netinet/if_ether.h>
#endif

#include <dev/ath/if_athvar.h>
#include <dev/ath/ath_rate/onoe/onoe.h>
#include <dev/ath/ath_hal/ah_desc.h>

/*
 * 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 */

static void	ath_rate_update(struct ath_softc *, struct ieee80211_node *,
			int rate);
static void	ath_rate_ctl_start(struct ath_softc *, struct ieee80211_node *);
static void	ath_rate_ctl(void *, struct ieee80211_node *);

void
ath_rate_node_init(struct ath_softc *sc, struct ath_node *an)
{
	/* NB: assumed to be zero'd by caller */
}

void
ath_rate_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
}

void
ath_rate_findrate(struct ath_softc *sc, struct ath_node *an,
	int shortPreamble, size_t frameLen,
	u_int8_t *rix, int *try0, u_int8_t *txrate)
{
	struct onoe_node *on = ATH_NODE_ONOE(an);

	*rix = on->on_tx_rix0;
	*try0 = on->on_tx_try0;
	if (shortPreamble)
		*txrate = on->on_tx_rate0sp;
	else
		*txrate = on->on_tx_rate0;
}

void
ath_rate_setupxtxdesc(struct ath_softc *sc, struct ath_node *an,
	struct ath_desc *ds, int shortPreamble, u_int8_t rix)
{
	struct onoe_node *on = ATH_NODE_ONOE(an);

	ath_hal_setupxtxdesc(sc->sc_ah, ds
		, on->on_tx_rate1sp, 2	/* series 1 */
		, on->on_tx_rate2sp, 2	/* series 2 */
		, on->on_tx_rate3sp, 2	/* series 3 */
	);
}

void
ath_rate_tx_complete(struct ath_softc *sc, struct ath_node *an,
	const struct ath_buf *bf)
{
	struct onoe_node *on = ATH_NODE_ONOE(an);
	const struct ath_tx_status *ts = &bf->bf_status.ds_txstat;

	if (ts->ts_status == 0)
		on->on_tx_ok++;
	else
		on->on_tx_err++;
	on->on_tx_retr += ts->ts_shortretry
			+ ts->ts_longretry;
	if (on->on_interval != 0 && ticks - on->on_ticks > on->on_interval) {
		ath_rate_ctl(sc, &an->an_node);
		on->on_ticks = ticks;
	}
}

void
ath_rate_newassoc(struct ath_softc *sc, struct ath_node *an, int isnew)
{
	if (isnew)
		ath_rate_ctl_start(sc, &an->an_node);
}

static void
ath_rate_update(struct ath_softc *sc, struct ieee80211_node *ni, int rate)
{
	struct ath_node *an = ATH_NODE(ni);
	struct onoe_node *on = ATH_NODE_ONOE(an);
	struct ieee80211vap *vap = ni->ni_vap;
	const HAL_RATE_TABLE *rt = sc->sc_currates;
	u_int8_t rix;

	KASSERT(rt != NULL, ("no rate table, mode %u", sc->sc_curmode));

	IEEE80211_NOTE(vap, IEEE80211_MSG_RATECTL, ni,
	     "%s: set xmit rate to %dM", __func__,
	     ni->ni_rates.rs_nrates > 0 ?
		(ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL) / 2 : 0);

	/*
	 * 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_rix = rate;
	ni->ni_txrate = ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL;
	on->on_tx_rix0 = sc->sc_rixmap[ni->ni_txrate];
	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;

	on->on_interval = ath_rateinterval;
	if (vap->iv_opmode == IEEE80211_M_STA)
		on->on_interval /= 2;
	on->on_interval = (on->on_interval * hz) / 1000;
}

/*
 * 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)
	const struct ieee80211_txparam *tp = ni->ni_txparms;
	int srate;

	KASSERT(ni->ni_rates.rs_nrates > 0, ("no rates"));
	if (tp == NULL || tp->ucastrate == 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--)
				;
		}
	} else {
		/*
		 * A fixed rate is to be used; ic_fixed_rate is the
		 * IEEE code for this rate (sans basic bit).  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.
		 */
		/* NB: the rate set is assumed sorted */
		srate = ni->ni_rates.rs_nrates - 1;
		for (; srate >= 0 && RATE(srate) != tp->ucastrate; srate--)
			;
	}
	/*
	 * The selected rate may not be available due to races
	 * and mode settings.  Also orphaned nodes created in
	 * adhoc mode may not have any rate set so this lookup
	 * can fail.  This is not fatal.
	 */
	ath_rate_update(sc, ni, srate < 0 ? 0 : srate);
#undef RATE
}

/*
 * 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;

	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
	    "ok %d err %d retr %d upper %d dir %d",
	    on->on_tx_ok, on->on_tx_err, on->on_tx_retr, on->on_tx_upper, dir);

	nrate = on->on_rix;
	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;
	}

	if (nrate != on->on_rix) {
		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
		    "%s: %dM -> %dM (%d ok, %d err, %d retr)", __func__,
		    ni->ni_txrate / 2,
		    (rs->rs_rates[nrate] & IEEE80211_RATE_VAL) / 2,
		    on->on_tx_ok, on->on_tx_err, on->on_tx_retr);
		ath_rate_update(sc, ni, nrate);
	} else if (enough)
		on->on_tx_ok = on->on_tx_err = on->on_tx_retr = 0;
}

static void
ath_rate_sysctlattach(struct ath_softc *sc)
{
	struct sysctl_ctx_list *ctx = device_get_sysctl_ctx(sc->sc_dev);
	struct sysctl_oid *tree = device_get_sysctl_tree(sc->sc_dev);

	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
		"rate_interval", CTLFLAG_RW, &ath_rateinterval, 0,
		"rate control: operation interval (ms)");
	/* XXX bounds check values */
	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
		"rate_raise", CTLFLAG_RW, &ath_rate_raise, 0,
		"rate control: retry threshold to credit rate raise (%%)");
	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
		"rate_raise_threshold", CTLFLAG_RW, &ath_rate_raise_threshold,0,
		"rate control: # good periods before raising rate");
}

struct ath_ratectrl *
ath_rate_attach(struct ath_softc *sc)
{
	struct onoe_softc *osc;

	osc = malloc(sizeof(struct onoe_softc), M_DEVBUF, M_NOWAIT|M_ZERO);
	if (osc == NULL)
		return NULL;
	osc->arc.arc_space = sizeof(struct onoe_node);
	ath_rate_sysctlattach(sc);

	return &osc->arc;
}

void
ath_rate_detach(struct ath_ratectrl *arc)
{
	struct onoe_softc *osc = (struct onoe_softc *) arc;

	free(osc, M_DEVBUF);
}