sys/net80211/ieee80211_amrr.c

root/sys/net80211/ieee80211_amrr.c
/*      $OpenBSD: ieee80211_amrr.c,v 1.1 2006/06/17 19:07:19 damien Exp $       */

/*-
 * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
 * Copyright (c) 2006
 *      Damien Bergamini <damien.bergamini@free.fr>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/cdefs.h>
/*-
 * Naive implementation of the Adaptive Multi Rate Retry algorithm:
 *
 * "IEEE 802.11 Rate Adaptation: A Practical Approach"
 *  Mathieu Lacage, Hossein Manshaei, Thierry Turletti
 *  INRIA Sophia - Projet Planete
 *  http://www-sop.inria.fr/rapports/sophia/RR-5208.html
 */
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/sbuf.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_media.h>
#include <net/ethernet.h>

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

#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_ht.h>
#include <net80211/ieee80211_vht.h>
#include <net80211/ieee80211_amrr.h>
#include <net80211/ieee80211_ratectl.h>

#define is_success(amn) \
        ((amn)->amn_retrycnt < (amn)->amn_txcnt / 10)
#define is_failure(amn) \
        ((amn)->amn_retrycnt > (amn)->amn_txcnt / 3)
#define is_enough(amn)          \
        ((amn)->amn_txcnt > 10)

static void     amrr_setinterval(const struct ieee80211vap *, int);
static void     amrr_init(struct ieee80211vap *);
static void     amrr_deinit(struct ieee80211vap *);
static void     amrr_node_init(struct ieee80211_node *);
static void     amrr_node_deinit(struct ieee80211_node *);
static int      amrr_update(struct ieee80211_amrr *,
                        struct ieee80211_amrr_node *, struct ieee80211_node *);
static int      amrr_rate(struct ieee80211_node *, void *, uint32_t);
static void     amrr_tx_complete(const struct ieee80211_node *,
                        const struct ieee80211_ratectl_tx_status *);
static void     amrr_tx_update_cb(void *, struct ieee80211_node *);
static void     amrr_tx_update(struct ieee80211vap *vap,
                        struct ieee80211_ratectl_tx_stats *);
static void     amrr_sysctlattach(struct ieee80211vap *,
                        struct sysctl_ctx_list *, struct sysctl_oid *);
static void     amrr_node_stats(struct ieee80211_node *ni, struct sbuf *s);

/* number of references from net80211 layer */
static  int nrefs = 0;

static const struct ieee80211_ratectl amrr = {
        .ir_name        = "amrr",
        .ir_attach      = NULL,
        .ir_detach      = NULL,
        .ir_init        = amrr_init,
        .ir_deinit      = amrr_deinit,
        .ir_node_init   = amrr_node_init,
        .ir_node_deinit = amrr_node_deinit,
        .ir_rate        = amrr_rate,
        .ir_tx_complete = amrr_tx_complete,
        .ir_tx_update   = amrr_tx_update,
        .ir_setinterval = amrr_setinterval,
        .ir_node_stats  = amrr_node_stats,
};
IEEE80211_RATECTL_MODULE(amrr, 1);
IEEE80211_RATECTL_ALG(amrr, IEEE80211_RATECTL_AMRR, amrr);

static void
amrr_setinterval(const struct ieee80211vap *vap, int msecs)
{
        struct ieee80211_amrr *amrr = vap->iv_rs;

        if (!amrr)
                return;

        if (msecs < 100)
                msecs = 100;
        amrr->amrr_interval = msecs_to_ticks(msecs);
}

static void
amrr_init(struct ieee80211vap *vap)
{
        struct ieee80211_amrr *amrr;

        KASSERT(vap->iv_rs == NULL, ("%s called multiple times", __func__));

        nrefs++;                /* XXX locking */
        amrr = vap->iv_rs = IEEE80211_MALLOC(sizeof(struct ieee80211_amrr),
            M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
        if (amrr == NULL) {
                net80211_vap_printf(vap, "couldn't alloc ratectl structure\n");
                return;
        }
        amrr->amrr_min_success_threshold = IEEE80211_AMRR_MIN_SUCCESS_THRESHOLD;
        amrr->amrr_max_success_threshold = IEEE80211_AMRR_MAX_SUCCESS_THRESHOLD;
        amrr_setinterval(vap, 500 /* ms */);
        amrr_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
}

static void
amrr_deinit(struct ieee80211vap *vap)
{
        KASSERT(nrefs > 0, ("imbalanced attach/detach"));
        IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
        vap->iv_rs = NULL;      /* guard */
        nrefs--;                /* XXX locking */
}

static void
amrr_node_init_vht(struct ieee80211_node *ni)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;

        /* Default to VHT NSS 1 MCS 2; should be reliable! */
        amn->amn_vht_mcs = 2;
        amn->amn_vht_nss = 1;
        ieee80211_node_set_txrate_vht_rate(ni, amn->amn_vht_nss,
            amn->amn_vht_mcs);

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: VHT: initial rate NSS %d MCS %d",
            amn->amn_vht_nss,
            amn->amn_vht_mcs);
}

static void
amrr_node_init_ht(struct ieee80211_node *ni)
{
        const struct ieee80211_rateset *rs;
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        uint8_t rate;   /* dot11rate */

        rs = (struct ieee80211_rateset *) &ni->ni_htrates;
        /* Initial rate - lowest */
        rate = rs->rs_rates[0];

        /* Pick something low that's likely to succeed */
        for (amn->amn_rix = rs->rs_nrates - 1; amn->amn_rix > 0;
            amn->amn_rix--) {
                /* 11n - stop at MCS4 */
                if ((rs->rs_rates[amn->amn_rix] & 0x1f) < 4)
                        break;
        }
        rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;

        /* Ensure the MCS bit is set */
        rate |= IEEE80211_RATE_MCS;

        /* Assign initial rate from the rateset */
        ieee80211_node_set_txrate_dot11rate(ni, rate);

        /* XXX TODO: we really need a rate-to-string method */
        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: nrates=%d, initial rate MCS %d",
            rs->rs_nrates,
            (rate & IEEE80211_RATE_VAL));
}

static void
amrr_node_init_legacy(struct ieee80211_node *ni)
{
        const struct ieee80211_rateset *rs;
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        uint8_t rate;   /* dot11rate */

        rs = &ni->ni_rates;
        /* Initial rate - lowest */
        rate = rs->rs_rates[0];

        /* Clear the basic rate flag if it's not 11n */
        rate &= IEEE80211_RATE_VAL;

        /* Pick something low that's likely to succeed */
        for (amn->amn_rix = rs->rs_nrates - 1; amn->amn_rix > 0;
            amn->amn_rix--) {
                /* legacy - anything < 36mbit, stop searching */
                if ((rs->rs_rates[amn->amn_rix] &
                    IEEE80211_RATE_VAL) <= 72)
                        break;
        }
        rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;

        /* Assign initial rate from the rateset */
        ieee80211_node_set_txrate_dot11rate(ni, rate);

        /* XXX TODO: we really need a rate-to-string method */
        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: nrates=%d, initial rate %d Mb",
            rs->rs_nrates,
            (rate & IEEE80211_RATE_VAL) / 2);
}

static void
amrr_node_init(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_amrr *amrr = vap->iv_rs;
        struct ieee80211_amrr_node *amn;

        if (!amrr) {
                net80211_vap_printf(vap,
                    "ratectl structure was not allocated, "
                    "per-node structure allocation skipped\n");
                return;
        }

        if (ni->ni_rctls == NULL) {
                ni->ni_rctls = amn = IEEE80211_MALLOC(sizeof(struct ieee80211_amrr_node),
                    M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
                if (amn == NULL) {
                        net80211_vap_printf(vap,
                            "couldn't alloc per-node ratectl structure\n");
                        return;
                }
        } else
                amn = ni->ni_rctls;

        /* Common state */
        amn->amn_amrr = amrr;
        amn->amn_success = 0;
        amn->amn_recovery = 0;
        amn->amn_txcnt = amn->amn_retrycnt = 0;
        amn->amn_success_threshold = amrr->amrr_min_success_threshold;
        amn->amn_ticks = ticks;

        /* Pick the right rateset */
        if (ieee80211_vht_check_tx_vht(ni))
                amrr_node_init_vht(ni);
        else if (ieee80211_ht_check_tx_ht(ni))
                amrr_node_init_ht(ni);
        else
                amrr_node_init_legacy(ni);
}

static void
amrr_node_deinit(struct ieee80211_node *ni)
{
        IEEE80211_FREE(ni->ni_rctls, M_80211_RATECTL);
}

static void
amrr_update_vht_inc(struct ieee80211_node *ni)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        uint8_t nss, mcs;

        /*
         * For now just keep looping over MCS to 9, then NSS up, checking if
         * it's valid via ieee80211_vht_node_check_tx_valid_mcs(),
         * until we hit max.  This at least tests the VHT MCS rates,
         * but definitely is suboptimal (in the same way the 11n MCS selection
         * is suboptimal.)
         */
        nss = amn->amn_vht_nss;
        mcs = amn->amn_vht_mcs;

        while (nss <= 8 && mcs <= 9) {
                /* Increment MCS 0..9, NSS 1..8 */
                if (mcs == 9) {
                        mcs = 0;
                        nss++;
                } else
                        mcs++;
                if (nss > 8)
                        break;

                if (ieee80211_vht_node_check_tx_valid_mcs(ni, ni->ni_chw, nss,
                    mcs)) {
                        amn->amn_vht_nss = nss;
                        amn->amn_vht_mcs = mcs;
                        break;
                }
        }
}

static void
amrr_update_vht_dec(struct ieee80211_node *ni)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        uint8_t nss, mcs;

        /*
         * For now just keep looping over MCS 9 .. 0 then NSS down, checking if
         * it's valid via ieee80211_vht_node_check_tx_valid_mcs(),
         * until we hit min.  This at least tests the VHT MCS rates,
         * but definitely is suboptimal (in the same way the 11n MCS selection
         * is suboptimal.
         */
        nss = amn->amn_vht_nss;
        mcs = amn->amn_vht_mcs;

        while (nss >= 1 && mcs >= 0) {

                if (mcs == 0) {
                        mcs = 9;
                        nss--;
                } else
                        mcs--;
                if (nss < 1)
                        break;

                if (ieee80211_vht_node_check_tx_valid_mcs(ni, ni->ni_chw, nss,
                    mcs)) {
                        amn->amn_vht_nss = nss;
                        amn->amn_vht_mcs = mcs;
                        break;
                }
        }
}

/*
 * A placeholder / temporary hack VHT rate control.
 *
 * Use the available MCS rates at the current node bandwidth
 * and configured / negotiated MCS rates.
 */
static int
amrr_update_vht(struct ieee80211_node *ni)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        struct ieee80211_amrr *amrr = ni->ni_vap->iv_rs;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: VHT: current rate NSS %d MCS %d, txcnt=%d, retrycnt=%d",
            amn->amn_vht_nss, amn->amn_vht_mcs, amn->amn_txcnt,
            amn->amn_retrycnt);

        if (is_success(amn)) {
                amn->amn_success++;
                if (amn->amn_success >= amn->amn_success_threshold) {
                        amn->amn_recovery = 1;
                        amn->amn_success = 0;

                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR: VHT: increase rate (txcnt=%d retrycnt=%d)",
                            amn->amn_txcnt, amn->amn_retrycnt);

                        amrr_update_vht_inc(ni);
                } else {
                        amn->amn_recovery = 0;
                }
        } else if (is_failure(amn)) {
                amn->amn_success = 0;

                if (amn->amn_recovery) {
                        amn->amn_success_threshold *= 2;
                        if (amn->amn_success_threshold >
                            amrr->amrr_max_success_threshold)
                                amn->amn_success_threshold =
                                    amrr->amrr_max_success_threshold;
                } else {
                        amn->amn_success_threshold =
                            amrr->amrr_min_success_threshold;
                }
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                    "AMRR: VHT: decreasing rate (txcnt=%d retrycnt=%d)",
                    amn->amn_txcnt, amn->amn_retrycnt);

                amrr_update_vht_dec(ni);

                amn->amn_recovery = 0;
        }

        /* Reset counters */
        amn->amn_txcnt = 0;
        amn->amn_retrycnt = 0;

        /* Return 0, not useful anymore */
        return (0);
}

static int
amrr_update_ht(struct ieee80211_amrr *amrr, struct ieee80211_amrr_node *amn,
    struct ieee80211_node *ni)
{
        int rix = amn->amn_rix;
        const struct ieee80211_rateset *rs;

        rs = (struct ieee80211_rateset *)&ni->ni_htrates;

        /* XXX TODO: we really need a rate-to-string method */
        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: current rate MCS %d, txcnt=%d, retrycnt=%d",
            rs->rs_rates[rix] & IEEE80211_RATE_VAL,
            amn->amn_txcnt,
            amn->amn_retrycnt);

        /*
         * XXX This is totally bogus for 11n, as although high MCS
         * rates for each stream may be failing, the next stream
         * should be checked.
         *
         * Eg, if MCS5 is ok but MCS6/7 isn't, and we can go up to
         * MCS23, we should skip 6/7 and try 8 onwards.
         */
        if (is_success(amn)) {
                amn->amn_success++;
                if (amn->amn_success >= amn->amn_success_threshold &&
                    rix + 1 < rs->rs_nrates) {
                        amn->amn_recovery = 1;
                        amn->amn_success = 0;
                        rix++;
                        /* XXX TODO: we really need a rate-to-string method */
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR increasing rate MCS %d "
                            "(txcnt=%d retrycnt=%d)",
                            rs->rs_rates[rix] & IEEE80211_RATE_VAL,
                            amn->amn_txcnt, amn->amn_retrycnt);
                } else {
                        amn->amn_recovery = 0;
                }
        } else if (is_failure(amn)) {
                amn->amn_success = 0;
                if (rix > 0) {
                        if (amn->amn_recovery) {
                                amn->amn_success_threshold *= 2;
                                if (amn->amn_success_threshold >
                                    amrr->amrr_max_success_threshold)
                                        amn->amn_success_threshold =
                                            amrr->amrr_max_success_threshold;
                        } else {
                                amn->amn_success_threshold =
                                    amrr->amrr_min_success_threshold;
                        }
                        rix--;
                        /* XXX TODO: we really need a rate-to-string method */
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR decreasing rate MCS %d "
                            "(txcnt=%d retrycnt=%d)",
                            rs->rs_rates[rix] & IEEE80211_RATE_VAL,
                            amn->amn_txcnt, amn->amn_retrycnt);
                }
                amn->amn_recovery = 0;
        }

        return (rix);
}

static int
amrr_update_legacy(struct ieee80211_amrr *amrr, struct ieee80211_amrr_node *amn,
    struct ieee80211_node *ni)
{
        int rix = amn->amn_rix;
        const struct ieee80211_rateset *rs;

        rs = &ni->ni_rates;

        /* XXX TODO: we really need a rate-to-string method */
        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: current rate %d Mb, txcnt=%d, retrycnt=%d",
            (rs->rs_rates[rix] & IEEE80211_RATE_VAL) / 2,
            amn->amn_txcnt,
            amn->amn_retrycnt);

        if (is_success(amn)) {
                amn->amn_success++;
                if (amn->amn_success >= amn->amn_success_threshold &&
                    rix + 1 < rs->rs_nrates) {
                        amn->amn_recovery = 1;
                        amn->amn_success = 0;
                        rix++;
                        /* XXX TODO: we really need a rate-to-string method */
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR increasing rate %d Mb (txcnt=%d retrycnt=%d)",
                            (rs->rs_rates[rix] & IEEE80211_RATE_VAL) / 2,
                            amn->amn_txcnt, amn->amn_retrycnt);
                } else {
                        amn->amn_recovery = 0;
                }
        } else if (is_failure(amn)) {
                amn->amn_success = 0;
                if (rix > 0) {
                        if (amn->amn_recovery) {
                                amn->amn_success_threshold *= 2;
                                if (amn->amn_success_threshold >
                                    amrr->amrr_max_success_threshold)
                                        amn->amn_success_threshold =
                                            amrr->amrr_max_success_threshold;
                        } else {
                                amn->amn_success_threshold =
                                    amrr->amrr_min_success_threshold;
                        }
                        rix--;
                        /* XXX TODO: we really need a rate-to-string method */
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR decreasing rate %d Mb (txcnt=%d retrycnt=%d)",
                            (rs->rs_rates[rix] & IEEE80211_RATE_VAL) / 2,
                            amn->amn_txcnt, amn->amn_retrycnt);
                }
                amn->amn_recovery = 0;
        }

        return (rix);
}

static int
amrr_update(struct ieee80211_amrr *amrr, struct ieee80211_amrr_node *amn,
    struct ieee80211_node *ni)
{
        int rix;

        KASSERT(is_enough(amn), ("txcnt %d", amn->amn_txcnt));

        /* Pick the right rateset */
        if (ieee80211_vht_check_tx_vht(ni))
                rix = amrr_update_vht(ni);
        else if (ieee80211_ht_check_tx_ht(ni))
                rix = amrr_update_ht(amrr, amn, ni);
        else
                rix = amrr_update_legacy(amrr, amn, ni);

        /* reset counters */
        amn->amn_txcnt = 0;
        amn->amn_retrycnt = 0;

        return (rix);
}

static int
amrr_rate_vht(struct ieee80211_node *ni)
{
        struct ieee80211_amrr *amrr = ni->ni_vap->iv_rs;
        struct ieee80211_amrr_node *amn = ni->ni_rctls;

        if (is_enough(amn) && (ticks - amn->amn_ticks) > amrr->amrr_interval)
                amrr_update_vht(ni);

        ieee80211_node_set_txrate_vht_rate(ni, amn->amn_vht_nss,
            amn->amn_vht_mcs);

        /* Note: There's no vht rs_rates, and the API doesn't use it anymore */
        return (0);
}

/*
 * Return the rate index to use in sending a data frame.
 * Update our internal state if it's been long enough.
 * If the rate changes we also update ni_txrate to match.
 */
static int
amrr_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg __unused)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        struct ieee80211_amrr *amrr;
        const struct ieee80211_rateset *rs = NULL;
        int rix;

        /* XXX should return -1 here, but drivers may not expect this... */
        if (!amn)
        {
                ieee80211_node_set_txrate_dot11rate(ni,
                    ni->ni_rates.rs_rates[0]);
                return 0;
        }

        if (ieee80211_vht_check_tx_vht(ni))
                return (amrr_rate_vht(ni));

        /* Pick the right rateset */
        if (ieee80211_ht_check_tx_ht(ni)) {
                /* XXX ew */
                rs = (struct ieee80211_rateset *) &ni->ni_htrates;
        } else {
                rs = &ni->ni_rates;
        }

        amrr = amn->amn_amrr;
        if (is_enough(amn) && (ticks - amn->amn_ticks) > amrr->amrr_interval) {
                rix = amrr_update(amrr, amn, ni);
                if (rix != amn->amn_rix) {
                        uint8_t dot11Rate;
                        /* update public rate */
                        dot11Rate = rs->rs_rates[rix];
                        /* XXX strip basic rate flag from txrate, if non-11n */
                        if (ieee80211_ht_check_tx_ht(ni))
                                dot11Rate |= IEEE80211_RATE_MCS;
                        else
                                dot11Rate &= IEEE80211_RATE_VAL;
                        ieee80211_node_set_txrate_dot11rate(ni, dot11Rate);

                        amn->amn_rix = rix;
                }
                amn->amn_ticks = ticks;
        } else
                rix = amn->amn_rix;
        return rix;
}

/*
 * Update statistics with tx complete status.  Ok is non-zero
 * if the packet is known to be ACK'd.  Retries has the number
 * retransmissions (i.e. xmit attempts - 1).
 */
static void
amrr_tx_complete(const struct ieee80211_node *ni,
    const struct ieee80211_ratectl_tx_status *status)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        int retries;

        if (!amn)
                return;

        retries = 0;
        if (status->flags & IEEE80211_RATECTL_STATUS_LONG_RETRY)
                retries = status->long_retries;

        amn->amn_txcnt++;
        if (status->status == IEEE80211_RATECTL_TX_SUCCESS)
                amn->amn_success++;
        amn->amn_retrycnt += retries;
}

static void
amrr_tx_update_cb(void *arg, struct ieee80211_node *ni)
{
        struct ieee80211_ratectl_tx_stats *stats = arg;
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        int txcnt, success, retrycnt;

        if (!amn)
                return;

        txcnt = stats->nframes;
        success = stats->nsuccess;
        retrycnt = 0;
        if (stats->flags & IEEE80211_RATECTL_TX_STATS_RETRIES)
                retrycnt = stats->nretries;

        amn->amn_txcnt += txcnt;
        amn->amn_success += success;
        amn->amn_retrycnt += retrycnt;
}

/*
 * Set tx count/retry statistics explicitly.  Intended for
 * drivers that poll the device for statistics maintained
 * in the device.
 */
static void
amrr_tx_update(struct ieee80211vap *vap,
    struct ieee80211_ratectl_tx_stats *stats)
{

        if (stats->flags & IEEE80211_RATECTL_TX_STATS_NODE)
                amrr_tx_update_cb(stats, stats->ni);
        else {
                ieee80211_iterate_nodes_vap(&vap->iv_ic->ic_sta, vap,
                    amrr_tx_update_cb, stats);
        }
}

static int
amrr_sysctl_interval(SYSCTL_HANDLER_ARGS)
{
        struct ieee80211vap *vap = arg1;
        struct ieee80211_amrr *amrr = vap->iv_rs;
        int msecs, error;

        if (!amrr)
                return ENOMEM;

        msecs = ticks_to_msecs(amrr->amrr_interval);
        error = sysctl_handle_int(oidp, &msecs, 0, req);
        if (error || !req->newptr)
                return error;
        amrr_setinterval(vap, msecs);
        return 0;
}

static void
amrr_sysctlattach(struct ieee80211vap *vap,
    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
{
        struct ieee80211_amrr *amrr = vap->iv_rs;

        if (!amrr)
                return;

        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "amrr_rate_interval", CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
            vap, 0, amrr_sysctl_interval, "I", "amrr operation interval (ms)");
        /* XXX bounds check values */
        SYSCTL_ADD_UINT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "amrr_max_sucess_threshold", CTLFLAG_RW,
            &amrr->amrr_max_success_threshold, 0, "");
        SYSCTL_ADD_UINT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "amrr_min_sucess_threshold", CTLFLAG_RW,
            &amrr->amrr_min_success_threshold, 0, "");
}

static void
amrr_print_node_rate(struct ieee80211_amrr_node *amn,
    struct ieee80211_node *ni, struct sbuf *s)
{
        int rate;
        struct ieee80211_rateset *rs;

        if (ieee80211_ht_check_tx_ht(ni)) {
                rs = (struct ieee80211_rateset *) &ni->ni_htrates;
                rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
                sbuf_printf(s, "rate: MCS %d\n", rate);
        } else {
                rs = &ni->ni_rates;
                rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
                sbuf_printf(s, "rate: %d Mbit\n", rate / 2);
        }
}

static void
amrr_node_stats(struct ieee80211_node *ni, struct sbuf *s)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;

        /* XXX TODO: check locking? */

        if (!amn)
                return;

        amrr_print_node_rate(amn, ni, s);
        sbuf_printf(s, "ticks: %d\n", amn->amn_ticks);
        sbuf_printf(s, "txcnt: %u\n", amn->amn_txcnt);
        sbuf_printf(s, "success: %u\n", amn->amn_success);
        sbuf_printf(s, "success_threshold: %u\n", amn->amn_success_threshold);
        sbuf_printf(s, "recovery: %u\n", amn->amn_recovery);
        sbuf_printf(s, "retry_cnt: %u\n", amn->amn_retrycnt);
}