xref: /freebsd/sys/dev/ath/ath_rate/sample/sample.c (revision fa20c234019ae7105ae5c4ae975e96ea8d66d7f3)

/*-
 * Copyright (c) 2005 John Bicket
 * 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * John Bicket's SampleRate control algorithm.
 */
#include "opt_inet.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/module.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/sample/sample.h>
#include <contrib/dev/ath/ah_desc.h>

#define	SAMPLE_DEBUG
#ifdef SAMPLE_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

/*
 * This file is an implementation of the SampleRate algorithm
 * in "Bit-rate Selection in Wireless Networks"
 * (http://www.pdos.lcs.mit.edu/papers/jbicket-ms.ps)
 *
 * SampleRate chooses the bit-rate it predicts will provide the most
 * throughput based on estimates of the expected per-packet
 * transmission time for each bit-rate.  SampleRate periodically sends
 * packets at bit-rates other than the current one to estimate when
 * another bit-rate will provide better performance. SampleRate
 * switches to another bit-rate when its estimated per-packet
 * transmission time becomes smaller than the current bit-rate's.
 * SampleRate reduces the number of bit-rates it must sample by
 * eliminating those that could not perform better than the one
 * currently being used.  SampleRate also stops probing at a bit-rate
 * if it experiences several successive losses.
 *
 * The difference between the algorithm in the thesis and the one in this
 * file is that the one in this file uses a ewma instead of a window.
 *
 */

static void	ath_rate_ctl_start(struct ath_softc *, struct ieee80211_node *);

static __inline int size_to_bin(int size)
{
	int x = 0;
	for (x = 0; x < NUM_PACKET_SIZE_BINS; x++) {
		if (size < packet_size_bins[x]) {
			return x;
		}
	}
	return NUM_PACKET_SIZE_BINS-1;
}
static __inline int bin_to_size(int index) {
	return packet_size_bins[index];
}

/*
 * Setup rate codes for management/control frames.  We force
 * all such frames to the lowest rate.
 */
static void
ath_rate_setmgtrates(struct ath_softc *sc, struct ath_node *an)
{
	const HAL_RATE_TABLE *rt = sc->sc_currates;

	/* setup rates for management frames */
	/* XXX management/control frames always go at lowest speed */
	an->an_tx_mgtrate = rt->info[0].rateCode;
	an->an_tx_mgtratesp = an->an_tx_mgtrate
			    | rt->info[0].shortPreamble;
}

void
ath_rate_node_init(struct ath_softc *sc, struct ath_node *an)
{
	DPRINTF(sc, "%s:\n", __func__);
	/* NB: assumed to be zero'd by caller */
	ath_rate_setmgtrates(sc, an);
}

void
ath_rate_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
	DPRINTF(sc, "%s:\n", __func__);
}


/*
 * returns the ndx with the lowest average_tx_time,
 * or -1 if all the average_tx_times are 0.
 */
static __inline int best_rate_ndx(struct sample_node *sn, int size_bin)
{
	int x = 0;
        int best_rate_ndx = 0;
        int best_rate_tt = 0;
        for (x = 0; x < sn->num_rates; x++) {
		int tt = sn->stats[size_bin][x].average_tx_time;
		if (tt > 0) {
			if (!best_rate_tt || best_rate_tt > tt) {
				best_rate_tt = tt;
				best_rate_ndx = x;
			}
		}
        }
        return (best_rate_tt) ? best_rate_ndx : -1;
}

/*
 * pick a ndx s.t. the perfect_tx_time
 * is less than the best bit-rate's average_tx_time
 * and the ndx has not had four successive failures.
 */
static __inline int pick_sample_ndx(struct sample_node *sn, int size_bin)
{
	int x = 0;
	int best_ndx = best_rate_ndx(sn, size_bin);
	int best_tt = 0;
	int num_eligible = 0;

	if (best_ndx < 0) {
		/* no successes yet, send at the lowest bit-rate */
		return 0;
	}

	best_tt = sn->stats[size_bin][best_ndx].average_tx_time;
	sn->sample_num[size_bin]++;

	/*
	 * first, find the number of bit-rates we could potentially
	 * sample. we assume this list doesn't change a lot, so
	 * we will just cycle through them.
	 */
	for (x = 0; x < sn->num_rates; x++) {
		if (x != best_ndx &&
		    sn->stats[size_bin][x].perfect_tx_time < best_tt &&
		    sn->stats[size_bin][x].successive_failures < 4) {
			num_eligible++;
		}
	}

	if (num_eligible > 0) {
		int pick = sn->sample_num[size_bin] % num_eligible;
		for (x = 0; x < sn->num_rates; x++) {
			if (x != best_ndx &&
			    sn->stats[size_bin][x].perfect_tx_time < best_tt &&
			    sn->stats[size_bin][x].successive_failures < 4) {
				if (pick == 0) {
					return x;
				}
				pick--;
			}
		}
	}
	return best_ndx;
}

void
ath_rate_findrate(struct ath_softc *sc, struct ath_node *an,
		  HAL_BOOL shortPreamble, size_t frameLen,
		  u_int8_t *rix, int *try0, u_int8_t *txrate)
{
	struct sample_node *sn = ATH_NODE_SAMPLE(an);
	struct sample_softc *ssc = ATH_SOFTC_SAMPLE(sc);
	int x;
	int ndx = 0;
	int size_bin = size_to_bin(frameLen);
	int best_ndx = best_rate_ndx(sn, size_bin);

	if (sn->static_rate_ndx != -1) {
		*try0 = 4;
		*rix = sn->rates[sn->static_rate_ndx].rix;
		*txrate = sn->rates[sn->static_rate_ndx].rateCode;
		return;
	}

	*try0 = 2;

	best_ndx = best_rate_ndx(sn, size_bin);
	if (!sn->packets_sent[size_bin] ||
	    sn->packets_sent[size_bin] % ssc->ath_sample_rate > 0) {
		/*
		 * for most packets, send the packet at the bit-rate with
		 * the lowest estimated transmission time.
		 */
		if (best_ndx != -1) {
			ndx = best_ndx;
		} else {
			/*
			 * no packet has succeeded, try the highest bitrate
			 * that hasn't failed.
			 */
			for (ndx = sn->num_rates-1; ndx >= 0; ndx--) {
				if (sn->stats[size_bin][ndx].successive_failures == 0) {
					break;
				}
			}
		}
		if (size_bin == 0) {
			/* update the visible txrate for this node */
			an->an_node.ni_txrate = ndx;
		}
	} else {
		/*
		 * before we pick a bit-rate to "sample", clear any
		 * stale stuff out.
		 */
		for (x = 0; x < sn->num_rates; x++) {
			if (ticks - sn->stats[size_bin][x].last_tx > ((hz * 10000)/1000)) {
				sn->stats[size_bin][x].average_tx_time = sn->stats[size_bin][x].perfect_tx_time;
				sn->stats[size_bin][x].successive_failures = 0;
				sn->stats[size_bin][x].tries = 0;
				sn->stats[size_bin][x].total_packets = 0;
				sn->stats[size_bin][x].packets_acked = 0;
			}
		}

		/* send the packet at a different bit-rate */
		ndx = pick_sample_ndx(sn, size_bin);
	}


	*rix = sn->rates[ndx].rix;
	if (shortPreamble) {
		*txrate = sn->rates[ndx].shortPreambleRateCode;
	} else {

		*txrate = sn->rates[ndx].rateCode;
	}

	sn->packets_sent[size_bin]++;
}

void
ath_rate_setupxtxdesc(struct ath_softc *sc, struct ath_node *an,
		      struct ath_desc *ds, HAL_BOOL shortPreamble, u_int8_t rix)
{
	struct sample_node *sn = ATH_NODE_SAMPLE(an);
	int rateCode = -1;
	int frame_size;
	int size_bin;
	int best_ndx;

	frame_size = ds->ds_ctl0 & 0x0fff; /* low-order 12 bits of ds_ctl0 */
	if (frame_size == 0)
		frame_size = 1500;
	size_bin = size_to_bin(frame_size);
	best_ndx = best_rate_ndx(sn, size_bin);

	if (best_ndx == -1 || !sn->stats[size_bin][best_ndx].packets_acked) {
		/*
		 * no packet has succeeded, so also try twice at the lowest bitate.
		 */
		if (shortPreamble) {
			rateCode = sn->rates[0].shortPreambleRateCode;
		} else {
			rateCode = sn->rates[0].rateCode;
		}
	} else if (sn->rates[best_ndx].rix != rix) {
		/*
		 * we're trying a different bit-rate, and it could be lossy,
		 * so if it fails try at the best bit-rate.
		 */
		if (shortPreamble) {
			rateCode = sn->rates[MAX(0,best_ndx-1)].shortPreambleRateCode;
		} else {
			rateCode = sn->rates[MAX(0,best_ndx-1)].rateCode;
		}
	}
	if (rateCode != -1) {
		ath_hal_setupxtxdesc(sc->sc_ah, ds
				     , rateCode, 1	/* series 1 */
				     , rateCode, 1	        /* series 2 */
				     , rateCode, 1	        /* series 3 */
				     );
	}

}

void
ath_rate_tx_complete(struct ath_softc *sc,
		     struct ath_node *an, const struct ath_desc *ds)
{
	struct sample_node *sn = ATH_NODE_SAMPLE(an);
	struct sample_softc *ssc = ATH_SOFTC_SAMPLE(sc);
	int rate = sc->sc_hwmap[ds->ds_txstat.ts_rate &~ HAL_TXSTAT_ALTRATE].ieeerate;
	int retries = ds->ds_txstat.ts_longretry;
	int initial_rate_failed = ((ds->ds_txstat.ts_rate & HAL_TXSTAT_ALTRATE)
				   || ds->ds_txstat.ts_status != 0 ||
				   retries > 3);
	int tt = 0;
	int rix = -1;
	int x = 0;
	int frame_size; /* low-order 12 bits of ds_ctl0 */
	int size_bin;
	int size;

	if (!sn->num_rates) {
		DPRINTF(sc, "%s: no rates yet\n", __func__);
		return;
	}
	for (x = 0; x < sn->num_rates; x++) {
		if (sn->rates[x].rate == rate) {
			rix = x;
			break;
		}
	}

	if (rix < 0 || rix > sn->num_rates) {
		/* maybe a management packet */
		return;
	}

	frame_size = ds->ds_ctl0 & 0x0fff; /* low-order 12 bits of ds_ctl0 */
	if (frame_size == 0)
		frame_size = 1500;
	size_bin = size_to_bin(frame_size);
	size = bin_to_size(size_bin);
	tt = calc_usecs_unicast_packet(sc, size, sn->rates[rix].rix,
				       retries);

	DPRINTF(sc, "%s: rate %d rix %d frame_size %d (%d) retries %d status %d tt %d avg_tt %d perfect_tt %d ts-rate %d\n",
		__func__, rate, rix, frame_size, size, retries, initial_rate_failed, tt,
		sn->stats[size_bin][rix].average_tx_time,
		sn->stats[size_bin][rix].perfect_tx_time,
		ds->ds_txstat.ts_rate);

	if (sn->stats[size_bin][rix].total_packets < 7) {
		/* just average the first few packets */
		int avg_tx = sn->stats[size_bin][rix].average_tx_time;
		int packets = sn->stats[size_bin][rix].total_packets;
		sn->stats[size_bin][rix].average_tx_time = (tt+(avg_tx*packets))/(packets+1);
	} else {
		/* use a ewma */
		sn->stats[size_bin][rix].average_tx_time =
			((sn->stats[size_bin][rix].average_tx_time * ssc->ath_smoothing_rate) +
			 (tt * (100 - ssc->ath_smoothing_rate))) / 100;
	}

	if (initial_rate_failed) {
		/*
		 * this packet failed - count this as a failure
		 * for larger packets also, since we assume
		 * if a small packet fails at a lower bit-rate
		 * then a larger one will also.
		 */
		int y;
		for (y = size_bin; y < NUM_PACKET_SIZE_BINS; y++) {
			sn->stats[y][rix].successive_failures++;
			sn->stats[y][rix].last_tx = ticks;
		}
	} else {
		sn->stats[size_bin][rix].packets_acked++;
		sn->stats[size_bin][rix].successive_failures = 0;
	}
	sn->stats[size_bin][rix].tries += (1+retries);
	sn->stats[size_bin][rix].last_tx = ticks;
	sn->stats[size_bin][rix].total_packets++;
}

void
ath_rate_newassoc(struct ath_softc *sc, struct ath_node *an, int isnew)
{
	DPRINTF(sc, "%s:\n", __func__);
	if (isnew)
		ath_rate_ctl_start(sc, &an->an_node);
}

static void
ath_rate_ctl_reset(struct ath_softc *sc, struct ieee80211_node *ni)
{
	struct ath_node *an = ATH_NODE(ni);
	struct sample_node *sn = ATH_NODE_SAMPLE(an);
	int x = 0;
	int y = 0;

	for (y = 0; y < NUM_PACKET_SIZE_BINS; y++) {
		int size = bin_to_size(y);
		sn->packets_sent[y] = 0;
		sn->sample_num[y] = 0;

		for (x = 0; x < ni->ni_rates.rs_nrates; x++) {
			sn->stats[y][x].successive_failures = 0;
			sn->stats[y][x].tries = 0;
			sn->stats[y][x].total_packets = 0;
			sn->stats[y][x].packets_acked = 0;
			sn->stats[y][x].last_tx = 0;
			sn->stats[y][x].perfect_tx_time = calc_usecs_unicast_packet(sc, size,
									      sn->rates[x].rix,
									      0);
			sn->stats[y][x].average_tx_time = sn->stats[y][x].perfect_tx_time;


			DPRINTF(sc, "%s: %d rate %d rix %d rateCode %d perfect_tx_time %d \n", __func__,
				x, sn->rates[x].rate,
				sn->rates[x].rix, sn->rates[x].rateCode,
				sn->stats[0][x].perfect_tx_time);
		}

	}

	/* set the visible bit-rate to the lowest one available */
	ni->ni_txrate = 0;

}

/*
 * Initialize the tables 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;
	struct ath_node *an = ATH_NODE(ni);
	struct sample_node *sn = ATH_NODE_SAMPLE(an);
	const HAL_RATE_TABLE *rt = sc->sc_currates;

	int x;
	int srate;

        DPRINTF(sc, "%s:\n", __func__);
	KASSERT(rt != NULL, ("no rate table, mode %u", sc->sc_curmode));
	KASSERT(ni->ni_rates.rs_nrates > 0, ("no rates"));
        sn->static_rate_ndx = -1;
	if (ic->ic_fixed_rate != -1) {
		/*
		 * 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--)
			;
		KASSERT(srate >= 0,
			("fixed rate %d not in rate set", ic->ic_fixed_rate));
                sn->static_rate_ndx = srate;

	}
	sn->num_rates = ni->ni_rates.rs_nrates;
        for (x = 0; x < ni->ni_rates.rs_nrates; x++) {
          sn->rates[x].rate = ni->ni_rates.rs_rates[x] & IEEE80211_RATE_VAL;
          sn->rates[x].rix = sc->sc_rixmap[sn->rates[x].rate];
          sn->rates[x].rateCode = rt->info[sn->rates[x].rix].rateCode;
          sn->rates[x].shortPreambleRateCode =
		  rt->info[sn->rates[x].rix].rateCode |
		  rt->info[sn->rates[x].rix].shortPreamble;
	}
	ath_rate_ctl_reset(sc, ni);

#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 ieee80211com *ic = &sc->sc_ic;

	if (state == IEEE80211_S_RUN)
		ath_rate_newassoc(sc, ATH_NODE(ic->ic_bss), 1);
}

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

	/* XXX bounds check [0..100] */
	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
		"smoothing_rate", CTLFLAG_RW, &osc->ath_smoothing_rate, 0,
		"rate control: retry threshold to credit rate raise (%%)");
	/* XXX bounds check [2..100] */
	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
		"sample_rate", CTLFLAG_RW, &osc->ath_sample_rate,0,
		"rate control: # good periods before raising rate");
}

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

	DPRINTF(sc, "%s:\n", __func__);
	osc = malloc(sizeof(struct sample_softc), M_DEVBUF, M_NOWAIT|M_ZERO);
	if (osc == NULL)
		return NULL;
	osc->arc.arc_space = sizeof(struct sample_node);
	osc->ath_smoothing_rate = 95;	/* ewma percentage (out of 100) */
	osc->ath_sample_rate = 10;	/* send a different bit-rate 1/X packets */
	ath_rate_sysctlattach(sc, osc);
	return &osc->arc;
}

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

	free(osc, M_DEVBUF);
}

/*
 * Module glue.
 */
static int
sample_modevent(module_t mod, int type, void *unused)
{
	switch (type) {
	case MOD_LOAD:
		if (bootverbose)
			printf("ath_rate: <SampleRate bit-rate selection algorithm>\n");
		return 0;
	case MOD_UNLOAD:
		return 0;
	}
	return EINVAL;
}

static moduledata_t sample_mod = {
	"ath_rate",
	sample_modevent,
	0
};
DECLARE_MODULE(ath_rate, sample_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
MODULE_VERSION(ath_rate, 1);
MODULE_DEPEND(ath_rate, wlan, 1, 1, 1);