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	int t;
121
122	if (msecs < 100)
123		msecs = 100;
124	t = msecs_to_ticks(msecs);
125	rs->interval = (t < 1) ? 1 : t;
126}
127
128static void
129rssadapt_init(struct ieee80211vap *vap)
130{
131	struct ieee80211_rssadapt *rs;
132
133	KASSERT(vap->iv_rs == NULL, ("%s: iv_rs already initialized",
134	    __func__));
135
136	nrefs++;		/* XXX locking */
137	vap->iv_rs = rs = IEEE80211_MALLOC(sizeof(struct ieee80211_rssadapt),
138	    M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
139	if (rs == NULL) {
140		if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
141		return;
142	}
143	rs->vap = vap;
144	rssadapt_setinterval(vap, 500 /* msecs */);
145	rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
146}
147
148static void
149rssadapt_deinit(struct ieee80211vap *vap)
150{
151	IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
152	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
153	nrefs--;		/* XXX locking */
154}
155
156static void
157rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
158{
159	long interval;
160
161	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
162	ra->ra_nfail = ra->ra_nok = 0;
163
164	/*
165	 * A node is eligible for its rate to be raised every 1/10 to 10
166	 * seconds, more eligible in proportion to recent packet rates.
167	 */
168	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
169	ra->ra_raise_interval = msecs_to_ticks(interval);
170}
171
172static void
173rssadapt_node_init(struct ieee80211_node *ni)
174{
175	struct ieee80211_rssadapt_node *ra;
176	struct ieee80211vap *vap = ni->ni_vap;
177	struct ieee80211_rssadapt *rsa = vap->iv_rs;
178	const struct ieee80211_rateset *rs = &ni->ni_rates;
179
180	if (ni->ni_rctls == NULL) {
181		ni->ni_rctls = ra =
182		    IEEE80211_MALLOC(sizeof(struct ieee80211_rssadapt_node),
183		        M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
184		if (ra == NULL) {
185			if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
186			    "structure\n");
187			return;
188		}
189	} else
190		ra = ni->ni_rctls;
191	ra->ra_rs = rsa;
192	ra->ra_rates = *rs;
193	rssadapt_updatestats(ra);
194
195	/* pick initial rate */
196	for (ra->ra_rix = rs->rs_nrates - 1;
197	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
198	     ra->ra_rix--)
199		;
200	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
201	ra->ra_ticks = ticks;
202
203	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
204	    "RSSADAPT initial rate %d", ni->ni_txrate);
205}
206
207static void
208rssadapt_node_deinit(struct ieee80211_node *ni)
209{
210
211	IEEE80211_FREE(ni->ni_rctls, M_80211_RATECTL);
212}
213
214static __inline int
215bucket(int pktlen)
216{
217	int i, top, thridx;
218
219	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
220	     i < IEEE80211_RSSADAPT_BKTS;
221	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
222		thridx = i;
223		if (pktlen <= top)
224			break;
225	}
226	return thridx;
227}
228
229static int
230rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
231{
232	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
233	u_int pktlen = iarg;
234	const struct ieee80211_rateset *rs = &ra->ra_rates;
235	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
236	int rix, rssi;
237
238	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
239		rssadapt_updatestats(ra);
240		ra->ra_ticks = ticks;
241	}
242
243	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
244
245	/* XXX this is average rssi, should be using last value */
246	rssi = ni->ni_ic->ic_node_getrssi(ni);
247	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
248		if ((*thrs)[rix] < (rssi << 8))
249			break;
250	if (rix != ra->ra_rix) {
251		/* update public rate */
252		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
253		ra->ra_rix = rix;
254
255		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
256		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
257		    ni->ni_txrate, pktlen, rssi);
258	}
259	return rix;
260}
261
262/*
263 * Adapt the data rate to suit the conditions.  When a transmitted
264 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
265 * raise the RSS threshold for transmitting packets of similar length at
266 * the same data rate.
267 */
268static void
269rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
270{
271	uint16_t last_thr;
272	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
273	u_int rix;
274
275	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
276
277	rix = ra->ra_rix;
278	last_thr = (*thrs)[rix];
279	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
280	    last_thr, (rssi << 8));
281
282	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
283	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
284	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
285	    last_thr, (*thrs)[rix], rssi);
286}
287
288static void
289rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
290{
291	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
292	uint16_t newthr, oldthr;
293	int rix;
294
295	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
296
297	rix = ra->ra_rix;
298	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
299		oldthr = (*thrs)[rix + 1];
300		if ((*thrs)[rix] == 0)
301			newthr = (rssi << 8);
302		else
303			newthr = (*thrs)[rix];
304		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
305		    oldthr, newthr);
306
307		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
308		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
309		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
310		    oldthr, newthr, rssi);
311
312		ra->ra_last_raise = ticks;
313	}
314}
315
316static void
317rssadapt_tx_complete(const struct ieee80211_node *ni,
318    const struct ieee80211_ratectl_tx_status *status)
319{
320	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
321	int pktlen, rssi;
322
323	if ((status->flags &
324	    (IEEE80211_RATECTL_STATUS_PKTLEN|IEEE80211_RATECTL_STATUS_RSSI)) !=
325	    (IEEE80211_RATECTL_STATUS_PKTLEN|IEEE80211_RATECTL_STATUS_RSSI))
326		return;
327
328	pktlen = status->pktlen;
329	rssi = status->rssi;
330
331	if (status->status == IEEE80211_RATECTL_TX_SUCCESS) {
332		ra->ra_nok++;
333		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
334		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
335			rssadapt_raise_rate(ra, pktlen, rssi);
336	} else {
337		ra->ra_nfail++;
338		rssadapt_lower_rate(ra, pktlen, rssi);
339	}
340}
341
342static int
343rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
344{
345	struct ieee80211vap *vap = arg1;
346	struct ieee80211_rssadapt *rs = vap->iv_rs;
347	int msecs = ticks_to_msecs(rs->interval);
348	int error;
349
350	error = sysctl_handle_int(oidp, &msecs, 0, req);
351	if (error || !req->newptr)
352		return error;
353	rssadapt_setinterval(vap, msecs);
354	return 0;
355}
356
357static void
358rssadapt_sysctlattach(struct ieee80211vap *vap,
359    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
360{
361
362	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
363	    "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
364	    0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
365}
366