1/*	$FreeBSD: releng/12.0/sys/net80211/ieee80211_rssadapt.c 326272 2017-11-27 15:23:17Z pfg $	*/
2/* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
3/*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
7 * Copyright (c) 2003, 2004 David Young.  All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or
10 * without modification, are permitted provided that the following
11 * conditions are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above
15 *    copyright notice, this list of conditions and the following
16 *    disclaimer in the documentation and/or other materials provided
17 *    with the distribution.
18 * 3. The name of David Young may not be used to endorse or promote
19 *    products derived from this software without specific prior
20 *    written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
23 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
24 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
25 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
26 * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
27 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
28 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
30 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
33 * OF SUCH DAMAGE.
34 */
35#include "opt_wlan.h"
36
37#include <sys/param.h>
38#include <sys/systm.h>
39#include <sys/kernel.h>
40#include <sys/malloc.h>
41#include <sys/module.h>
42#include <sys/socket.h>
43#include <sys/sysctl.h>
44
45#include <net/if.h>
46#include <net/if_var.h>
47#include <net/if_media.h>
48#include <net/ethernet.h>
49
50#include <net80211/ieee80211_var.h>
51#include <net80211/ieee80211_rssadapt.h>
52#include <net80211/ieee80211_ratectl.h>
53
54struct rssadapt_expavgctl {
55	/* RSS threshold decay. */
56	u_int rc_decay_denom;
57	u_int rc_decay_old;
58	/* RSS threshold update. */
59	u_int rc_thresh_denom;
60	u_int rc_thresh_old;
61	/* RSS average update. */
62	u_int rc_avgrssi_denom;
63	u_int rc_avgrssi_old;
64};
65
66static struct rssadapt_expavgctl master_expavgctl = {
67	.rc_decay_denom = 16,
68	.rc_decay_old = 15,
69	.rc_thresh_denom = 8,
70	.rc_thresh_old = 4,
71	.rc_avgrssi_denom = 8,
72	.rc_avgrssi_old = 4
73};
74
75#ifdef interpolate
76#undef interpolate
77#endif
78#define interpolate(parm, old, new) ((parm##_old * (old) + \
79                                     (parm##_denom - parm##_old) * (new)) / \
80				    parm##_denom)
81
82static void	rssadapt_setinterval(const struct ieee80211vap *, int);
83static void	rssadapt_init(struct ieee80211vap *);
84static void	rssadapt_deinit(struct ieee80211vap *);
85static void	rssadapt_updatestats(struct ieee80211_rssadapt_node *);
86static void	rssadapt_node_init(struct ieee80211_node *);
87static void	rssadapt_node_deinit(struct ieee80211_node *);
88static int	rssadapt_rate(struct ieee80211_node *, void *, uint32_t);
89static void	rssadapt_lower_rate(struct ieee80211_rssadapt_node *, int, int);
90static void	rssadapt_raise_rate(struct ieee80211_rssadapt_node *,
91			int, int);
92static void	rssadapt_tx_complete(const struct ieee80211_node *,
93			const struct ieee80211_ratectl_tx_status *);
94static void	rssadapt_sysctlattach(struct ieee80211vap *,
95			struct sysctl_ctx_list *, struct sysctl_oid *);
96
97/* number of references from net80211 layer */
98static	int nrefs = 0;
99
100static const struct ieee80211_ratectl rssadapt = {
101	.ir_name	= "rssadapt",
102	.ir_attach	= NULL,
103	.ir_detach	= NULL,
104	.ir_init	= rssadapt_init,
105	.ir_deinit	= rssadapt_deinit,
106	.ir_node_init	= rssadapt_node_init,
107	.ir_node_deinit	= rssadapt_node_deinit,
108	.ir_rate	= rssadapt_rate,
109	.ir_tx_complete	= rssadapt_tx_complete,
110	.ir_tx_update	= NULL,
111	.ir_setinterval	= rssadapt_setinterval,
112};
113IEEE80211_RATECTL_MODULE(rssadapt, 1);
114IEEE80211_RATECTL_ALG(rssadapt, IEEE80211_RATECTL_RSSADAPT, rssadapt);
115
116static void
117rssadapt_setinterval(const struct ieee80211vap *vap, int msecs)
118{
119	struct ieee80211_rssadapt *rs = vap->iv_rs;
120
121	if (!rs)
122		return;
123
124	if (msecs < 100)
125		msecs = 100;
126	rs->interval = msecs_to_ticks(msecs);
127}
128
129static void
130rssadapt_init(struct ieee80211vap *vap)
131{
132	struct ieee80211_rssadapt *rs;
133
134	KASSERT(vap->iv_rs == NULL, ("%s: iv_rs already initialized",
135	    __func__));
136
137	nrefs++;		/* XXX locking */
138	vap->iv_rs = rs = IEEE80211_MALLOC(sizeof(struct ieee80211_rssadapt),
139	    M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
140	if (rs == NULL) {
141		if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
142		return;
143	}
144	rs->vap = vap;
145	rssadapt_setinterval(vap, 500 /* msecs */);
146	rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
147}
148
149static void
150rssadapt_deinit(struct ieee80211vap *vap)
151{
152	IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
153	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
154	nrefs--;		/* XXX locking */
155}
156
157static void
158rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
159{
160	long interval;
161
162	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
163	ra->ra_nfail = ra->ra_nok = 0;
164
165	/*
166	 * A node is eligible for its rate to be raised every 1/10 to 10
167	 * seconds, more eligible in proportion to recent packet rates.
168	 */
169	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
170	ra->ra_raise_interval = msecs_to_ticks(interval);
171}
172
173static void
174rssadapt_node_init(struct ieee80211_node *ni)
175{
176	struct ieee80211_rssadapt_node *ra;
177	struct ieee80211vap *vap = ni->ni_vap;
178	struct ieee80211_rssadapt *rsa = vap->iv_rs;
179	const struct ieee80211_rateset *rs = &ni->ni_rates;
180
181	if (!rsa) {
182		if_printf(vap->iv_ifp, "ratectl structure was not allocated, "
183		    "per-node structure allocation skipped\n");
184		return;
185	}
186
187	if (ni->ni_rctls == NULL) {
188		ni->ni_rctls = ra =
189		    IEEE80211_MALLOC(sizeof(struct ieee80211_rssadapt_node),
190		        M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
191		if (ra == NULL) {
192			if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
193			    "structure\n");
194			return;
195		}
196	} else
197		ra = ni->ni_rctls;
198	ra->ra_rs = rsa;
199	ra->ra_rates = *rs;
200	rssadapt_updatestats(ra);
201
202	/* pick initial rate */
203	for (ra->ra_rix = rs->rs_nrates - 1;
204	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
205	     ra->ra_rix--)
206		;
207	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
208	ra->ra_ticks = ticks;
209
210	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
211	    "RSSADAPT initial rate %d", ni->ni_txrate);
212}
213
214static void
215rssadapt_node_deinit(struct ieee80211_node *ni)
216{
217
218	IEEE80211_FREE(ni->ni_rctls, M_80211_RATECTL);
219}
220
221static __inline int
222bucket(int pktlen)
223{
224	int i, top, thridx;
225
226	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
227	     i < IEEE80211_RSSADAPT_BKTS;
228	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
229		thridx = i;
230		if (pktlen <= top)
231			break;
232	}
233	return thridx;
234}
235
236static int
237rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
238{
239	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
240	u_int pktlen = iarg;
241	const struct ieee80211_rateset *rs;
242	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
243	int rix, rssi;
244
245	/* XXX should return -1 here, but drivers may not expect this... */
246	if (!ra)
247	{
248		ni->ni_txrate = ni->ni_rates.rs_rates[0];
249		return 0;
250	}
251
252	rs = &ra->ra_rates;
253	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
254		rssadapt_updatestats(ra);
255		ra->ra_ticks = ticks;
256	}
257
258	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
259
260	/* XXX this is average rssi, should be using last value */
261	rssi = ni->ni_ic->ic_node_getrssi(ni);
262	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
263		if ((*thrs)[rix] < (rssi << 8))
264			break;
265	if (rix != ra->ra_rix) {
266		/* update public rate */
267		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
268		ra->ra_rix = rix;
269
270		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
271		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
272		    ni->ni_txrate, pktlen, rssi);
273	}
274	return rix;
275}
276
277/*
278 * Adapt the data rate to suit the conditions.  When a transmitted
279 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
280 * raise the RSS threshold for transmitting packets of similar length at
281 * the same data rate.
282 */
283static void
284rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
285{
286	uint16_t last_thr;
287	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
288	u_int rix;
289
290	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
291
292	rix = ra->ra_rix;
293	last_thr = (*thrs)[rix];
294	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
295	    last_thr, (rssi << 8));
296
297	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
298	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
299	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
300	    last_thr, (*thrs)[rix], rssi);
301}
302
303static void
304rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
305{
306	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
307	uint16_t newthr, oldthr;
308	int rix;
309
310	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
311
312	rix = ra->ra_rix;
313	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
314		oldthr = (*thrs)[rix + 1];
315		if ((*thrs)[rix] == 0)
316			newthr = (rssi << 8);
317		else
318			newthr = (*thrs)[rix];
319		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
320		    oldthr, newthr);
321
322		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
323		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
324		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
325		    oldthr, newthr, rssi);
326
327		ra->ra_last_raise = ticks;
328	}
329}
330
331static void
332rssadapt_tx_complete(const struct ieee80211_node *ni,
333    const struct ieee80211_ratectl_tx_status *status)
334{
335	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
336	int pktlen, rssi;
337
338	if (!ra)
339		return;
340
341	if ((status->flags &
342	    (IEEE80211_RATECTL_STATUS_PKTLEN|IEEE80211_RATECTL_STATUS_RSSI)) !=
343	    (IEEE80211_RATECTL_STATUS_PKTLEN|IEEE80211_RATECTL_STATUS_RSSI))
344		return;
345
346	pktlen = status->pktlen;
347	rssi = status->rssi;
348
349	if (status->status == IEEE80211_RATECTL_TX_SUCCESS) {
350		ra->ra_nok++;
351		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
352		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
353			rssadapt_raise_rate(ra, pktlen, rssi);
354	} else {
355		ra->ra_nfail++;
356		rssadapt_lower_rate(ra, pktlen, rssi);
357	}
358}
359
360static int
361rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
362{
363	struct ieee80211vap *vap = arg1;
364	struct ieee80211_rssadapt *rs = vap->iv_rs;
365	int msecs, error;
366
367	if (!rs)
368		return ENOMEM;
369
370	msecs = ticks_to_msecs(rs->interval);
371	error = sysctl_handle_int(oidp, &msecs, 0, req);
372	if (error || !req->newptr)
373		return error;
374	rssadapt_setinterval(vap, msecs);
375	return 0;
376}
377
378static void
379rssadapt_sysctlattach(struct ieee80211vap *vap,
380    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
381{
382
383	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
384	    "rssadapt_rate_interval",
385	    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, vap, 0,
386	    rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
387}
388