1 /*	$FreeBSD: head/sys/net80211/ieee80211_rssadapt.c 206358 2010-04-07 15:29:13Z rpaulo $	*/
2 /* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
3 /*-
4  * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
5  * Copyright (c) 2003, 2004 David Young.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or
8  * without modification, are permitted provided that the following
9  * conditions are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above
13  *    copyright notice, this list of conditions and the following
14  *    disclaimer in the documentation and/or other materials provided
15  *    with the distribution.
16  * 3. The name of David Young may not be used to endorse or promote
17  *    products derived from this software without specific prior
18  *    written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
21  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
22  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
23  * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
24  * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
26  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
28  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
31  * OF SUCH DAMAGE.
32  */
33 #include "opt_wlan.h"
34 
35 #include <sys/param.h>
36 #include <sys/kernel.h>
37 #include <sys/module.h>
38 #include <sys/socket.h>
39 #include <sys/sysctl.h>
40 
41 #include <net/if.h>
42 #include <net/if_media.h>
43 
44 #include <netproto/802_11/ieee80211_var.h>
45 #include <netproto/802_11/ieee80211_rssadapt.h>
46 #include <netproto/802_11/ieee80211_ratectl.h>
47 
48 struct rssadapt_expavgctl {
49 	/* RSS threshold decay. */
50 	u_int rc_decay_denom;
51 	u_int rc_decay_old;
52 	/* RSS threshold update. */
53 	u_int rc_thresh_denom;
54 	u_int rc_thresh_old;
55 	/* RSS average update. */
56 	u_int rc_avgrssi_denom;
57 	u_int rc_avgrssi_old;
58 };
59 
60 static struct rssadapt_expavgctl master_expavgctl = {
61 	.rc_decay_denom = 16,
62 	.rc_decay_old = 15,
63 	.rc_thresh_denom = 8,
64 	.rc_thresh_old = 4,
65 	.rc_avgrssi_denom = 8,
66 	.rc_avgrssi_old = 4
67 };
68 
69 #ifdef interpolate
70 #undef interpolate
71 #endif
72 #define interpolate(parm, old, new) ((parm##_old * (old) + \
73                                      (parm##_denom - parm##_old) * (new)) / \
74 				    parm##_denom)
75 
76 static void	rssadapt_setinterval(const struct ieee80211vap *, int);
77 static void	rssadapt_init(struct ieee80211vap *);
78 static void	rssadapt_deinit(struct ieee80211vap *);
79 static void	rssadapt_updatestats(struct ieee80211_rssadapt_node *);
80 static void	rssadapt_node_init(struct ieee80211_node *);
81 static void	rssadapt_node_deinit(struct ieee80211_node *);
82 static int	rssadapt_rate(struct ieee80211_node *, void *, uint32_t);
83 static void	rssadapt_lower_rate(struct ieee80211_rssadapt_node *, int, int);
84 static void	rssadapt_raise_rate(struct ieee80211_rssadapt_node *,
85 			int, int);
86 static void	rssadapt_tx_complete(const struct ieee80211vap *,
87     			const struct ieee80211_node *, int,
88 			void *, void *);
89 static void	rssadapt_sysctlattach(struct ieee80211vap *,
90 			struct sysctl_ctx_list *, struct sysctl_oid *);
91 
92 /* number of references from net80211 layer */
93 static	int nrefs = 0;
94 
95 static const struct ieee80211_ratectl rssadapt = {
96 	.ir_name	= "rssadapt",
97 	.ir_attach	= NULL,
98 	.ir_detach	= NULL,
99 	.ir_init	= rssadapt_init,
100 	.ir_deinit	= rssadapt_deinit,
101 	.ir_node_init	= rssadapt_node_init,
102 	.ir_node_deinit	= rssadapt_node_deinit,
103 	.ir_rate	= rssadapt_rate,
104 	.ir_tx_complete	= rssadapt_tx_complete,
105 	.ir_tx_update	= NULL,
106 	.ir_setinterval	= rssadapt_setinterval,
107 };
108 IEEE80211_RATECTL_MODULE(rssadapt, 1);
109 IEEE80211_RATECTL_ALG(rssadapt, IEEE80211_RATECTL_RSSADAPT, rssadapt);
110 
111 static void
112 rssadapt_setinterval(const struct ieee80211vap *vap, int msecs)
113 {
114 	struct ieee80211_rssadapt *rs = vap->iv_rs;
115 	int t;
116 
117 	if (msecs < 100)
118 		msecs = 100;
119 	t = msecs_to_ticks(msecs);
120 	rs->interval = (t < 1) ? 1 : t;
121 }
122 
123 static void
124 rssadapt_init(struct ieee80211vap *vap)
125 {
126 	struct ieee80211_rssadapt *rs;
127 
128 	KASSERT(vap->iv_rs == NULL, ("%s: iv_rs already initialized",
129 	    __func__));
130 
131 	rs = kmalloc(sizeof(struct ieee80211_rssadapt), M_80211_RATECTL,
132 	    M_WAITOK|M_ZERO);
133 	vap->iv_rs = rs;
134 	rs->vap = vap;
135 	rssadapt_setinterval(vap, 500 /* msecs */);
136 	rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
137 }
138 
139 static void
140 rssadapt_deinit(struct ieee80211vap *vap)
141 {
142 	kfree(vap->iv_rs, M_80211_RATECTL);
143 }
144 
145 static void
146 rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
147 {
148 	long interval;
149 
150 	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
151 	ra->ra_nfail = ra->ra_nok = 0;
152 
153 	/*
154 	 * A node is eligible for its rate to be raised every 1/10 to 10
155 	 * seconds, more eligible in proportion to recent packet rates.
156 	 */
157 	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
158 	ra->ra_raise_interval = msecs_to_ticks(interval);
159 }
160 
161 static void
162 rssadapt_node_init(struct ieee80211_node *ni)
163 {
164 	struct ieee80211_rssadapt_node *ra;
165 	struct ieee80211_rssadapt *rsa = ni->ni_vap->iv_rs;
166 	const struct ieee80211_rateset *rs = &ni->ni_rates;
167 
168 	if (ni->ni_rctls == NULL) {
169 		ni->ni_rctls = ra =
170 		    kmalloc(sizeof(struct ieee80211_rssadapt_node),
171 			M_80211_RATECTL, M_WAITOK|M_ZERO);
172 	} else {
173 		ra = ni->ni_rctls;
174 	}
175 	ra->ra_rs = rsa;
176 	ra->ra_rates = *rs;
177 	rssadapt_updatestats(ra);
178 
179 	/* pick initial rate */
180 	for (ra->ra_rix = rs->rs_nrates - 1;
181 	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
182 	     ra->ra_rix--)
183 		;
184 	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
185 	ra->ra_ticks = ticks;
186 
187 	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
188 	    "RSSADAPT initial rate %d", ni->ni_txrate);
189 }
190 
191 static void
192 rssadapt_node_deinit(struct ieee80211_node *ni)
193 {
194 
195 	kfree(ni->ni_rctls, M_80211_RATECTL);
196 }
197 
198 static __inline int
199 bucket(int pktlen)
200 {
201 	int i, top, thridx;
202 
203 	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
204 	     i < IEEE80211_RSSADAPT_BKTS;
205 	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
206 		thridx = i;
207 		if (pktlen <= top)
208 			break;
209 	}
210 	return thridx;
211 }
212 
213 static int
214 rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
215 {
216 	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
217 	u_int pktlen = iarg;
218 	const struct ieee80211_rateset *rs = &ra->ra_rates;
219 	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
220 	int rix, rssi;
221 
222 	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
223 		rssadapt_updatestats(ra);
224 		ra->ra_ticks = ticks;
225 	}
226 
227 	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
228 
229 	/* XXX this is average rssi, should be using last value */
230 	rssi = ni->ni_ic->ic_node_getrssi(ni);
231 	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
232 		if ((*thrs)[rix] < (rssi << 8))
233 			break;
234 	if (rix != ra->ra_rix) {
235 		/* update public rate */
236 		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
237 		ra->ra_rix = rix;
238 
239 		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
240 		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
241 		    ni->ni_txrate, pktlen, rssi);
242 	}
243 	return rix;
244 }
245 
246 /*
247  * Adapt the data rate to suit the conditions.  When a transmitted
248  * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
249  * raise the RSS threshold for transmitting packets of similar length at
250  * the same data rate.
251  */
252 static void
253 rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
254 {
255 	uint16_t last_thr;
256 	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
257 	u_int rix;
258 
259 	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
260 
261 	rix = ra->ra_rix;
262 	last_thr = (*thrs)[rix];
263 	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
264 	    last_thr, (rssi << 8));
265 
266 	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
267 	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
268 	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
269 	    last_thr, (*thrs)[rix], rssi);
270 }
271 
272 static void
273 rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
274 {
275 	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
276 	uint16_t newthr, oldthr;
277 	int rix;
278 
279 	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
280 
281 	rix = ra->ra_rix;
282 	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
283 		oldthr = (*thrs)[rix + 1];
284 		if ((*thrs)[rix] == 0)
285 			newthr = (rssi << 8);
286 		else
287 			newthr = (*thrs)[rix];
288 		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
289 		    oldthr, newthr);
290 
291 		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
292 		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
293 		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
294 		    oldthr, newthr, rssi);
295 
296 		ra->ra_last_raise = ticks;
297 	}
298 }
299 
300 static void
301 rssadapt_tx_complete(const struct ieee80211vap *vap,
302     const struct ieee80211_node *ni, int success, void *arg1, void *arg2)
303 {
304 	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
305 	int pktlen = *(int *)arg1, rssi = *(int *)arg2;
306 
307 	if (success) {
308 		ra->ra_nok++;
309 		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
310 		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
311 			rssadapt_raise_rate(ra, pktlen, rssi);
312 	} else {
313 		ra->ra_nfail++;
314 		rssadapt_lower_rate(ra, pktlen, rssi);
315 	}
316 }
317 
318 static int
319 rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
320 {
321 	struct ieee80211vap *vap = arg1;
322 	struct ieee80211_rssadapt *rs = vap->iv_rs;
323 	int msecs = ticks_to_msecs(rs->interval);
324 	int error;
325 
326 	error = sysctl_handle_int(oidp, &msecs, 0, req);
327 	wlan_serialize_enter();
328 	if (error == 0 && req->newptr)
329 		rssadapt_setinterval(vap, msecs);
330 	wlan_serialize_exit();
331 
332 	return error;
333 }
334 
335 static void
336 rssadapt_sysctlattach(struct ieee80211vap *vap,
337     struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
338 {
339 
340 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
341 	    "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
342 	    0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
343 }
344