1 /*	$FreeBSD$	*/
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/systm.h>
37 #include <sys/kernel.h>
38 #include <sys/malloc.h>
39 #include <sys/module.h>
40 #include <sys/socket.h>
41 #include <sys/sysctl.h>
42 
43 #include <net/if.h>
44 #include <net/if_var.h>
45 #include <net/if_media.h>
46 #include <net/ethernet.h>
47 
48 #include <netproto/802_11/ieee80211_var.h>
49 #include <netproto/802_11/ieee80211_rssadapt.h>
50 #include <netproto/802_11/ieee80211_ratectl.h>
51 
52 struct rssadapt_expavgctl {
53 	/* RSS threshold decay. */
54 	u_int rc_decay_denom;
55 	u_int rc_decay_old;
56 	/* RSS threshold update. */
57 	u_int rc_thresh_denom;
58 	u_int rc_thresh_old;
59 	/* RSS average update. */
60 	u_int rc_avgrssi_denom;
61 	u_int rc_avgrssi_old;
62 };
63 
64 static struct rssadapt_expavgctl master_expavgctl = {
65 	.rc_decay_denom = 16,
66 	.rc_decay_old = 15,
67 	.rc_thresh_denom = 8,
68 	.rc_thresh_old = 4,
69 	.rc_avgrssi_denom = 8,
70 	.rc_avgrssi_old = 4
71 };
72 
73 #ifdef interpolate
74 #undef interpolate
75 #endif
76 #define interpolate(parm, old, new) ((parm##_old * (old) + \
77                                      (parm##_denom - parm##_old) * (new)) / \
78 				    parm##_denom)
79 
80 static void	rssadapt_setinterval(const struct ieee80211vap *, int);
81 static void	rssadapt_init(struct ieee80211vap *);
82 static void	rssadapt_deinit(struct ieee80211vap *);
83 static void	rssadapt_updatestats(struct ieee80211_rssadapt_node *);
84 static void	rssadapt_node_init(struct ieee80211_node *);
85 static void	rssadapt_node_deinit(struct ieee80211_node *);
86 static int	rssadapt_rate(struct ieee80211_node *, void *, uint32_t);
87 static void	rssadapt_lower_rate(struct ieee80211_rssadapt_node *, int, int);
88 static void	rssadapt_raise_rate(struct ieee80211_rssadapt_node *,
89 			int, int);
90 static void	rssadapt_tx_complete(const struct ieee80211vap *,
91     			const struct ieee80211_node *, int,
92 			void *, void *);
93 static void	rssadapt_sysctlattach(struct ieee80211vap *,
94 			struct sysctl_ctx_list *, struct sysctl_oid *);
95 
96 /* number of references from net80211 layer */
97 static	int nrefs = 0;
98 
99 static const struct ieee80211_ratectl rssadapt = {
100 	.ir_name	= "rssadapt",
101 	.ir_attach	= NULL,
102 	.ir_detach	= NULL,
103 	.ir_init	= rssadapt_init,
104 	.ir_deinit	= rssadapt_deinit,
105 	.ir_node_init	= rssadapt_node_init,
106 	.ir_node_deinit	= rssadapt_node_deinit,
107 	.ir_rate	= rssadapt_rate,
108 	.ir_tx_complete	= rssadapt_tx_complete,
109 	.ir_tx_update	= NULL,
110 	.ir_setinterval	= rssadapt_setinterval,
111 };
112 IEEE80211_RATECTL_MODULE(rssadapt, 1);
113 IEEE80211_RATECTL_ALG(rssadapt, IEEE80211_RATECTL_RSSADAPT, rssadapt);
114 
115 static void
116 rssadapt_setinterval(const struct ieee80211vap *vap, int msecs)
117 {
118 	struct ieee80211_rssadapt *rs = vap->iv_rs;
119 	int t;
120 
121 	if (msecs < 100)
122 		msecs = 100;
123 	t = msecs_to_ticks(msecs);
124 	rs->interval = (t < 1) ? 1 : t;
125 }
126 
127 static void
128 rssadapt_init(struct ieee80211vap *vap)
129 {
130 	struct ieee80211_rssadapt *rs;
131 
132 	KASSERT(vap->iv_rs == NULL, ("%s: iv_rs already initialized",
133 	    __func__));
134 
135 	vap->iv_rs = rs = kmalloc(sizeof(struct ieee80211_rssadapt),
136 	    M_80211_RATECTL, M_INTWAIT|M_ZERO);
137 	if (rs == NULL) {
138 		if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
139 		return;
140 	}
141 	rs->vap = vap;
142 	rssadapt_setinterval(vap, 500 /* msecs */);
143 	rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
144 }
145 
146 static void
147 rssadapt_deinit(struct ieee80211vap *vap)
148 {
149 	kfree(vap->iv_rs, M_80211_RATECTL);
150 }
151 
152 static void
153 rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
154 {
155 	long interval;
156 
157 	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
158 	ra->ra_nfail = ra->ra_nok = 0;
159 
160 	/*
161 	 * A node is eligible for its rate to be raised every 1/10 to 10
162 	 * seconds, more eligible in proportion to recent packet rates.
163 	 */
164 	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
165 	ra->ra_raise_interval = msecs_to_ticks(interval);
166 }
167 
168 static void
169 rssadapt_node_init(struct ieee80211_node *ni)
170 {
171 	struct ieee80211_rssadapt_node *ra;
172 	struct ieee80211vap *vap = ni->ni_vap;
173 	struct ieee80211_rssadapt *rsa = vap->iv_rs;
174 	const struct ieee80211_rateset *rs = &ni->ni_rates;
175 
176 	if (ni->ni_rctls == NULL) {
177 		ni->ni_rctls = ra =
178 		    kmalloc(sizeof(struct ieee80211_rssadapt_node),
179 		        M_80211_RATECTL, M_INTWAIT|M_ZERO);
180 		if (ra == NULL) {
181 			if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
182 			    "structure\n");
183 			return;
184 		}
185 	} else
186 		ra = ni->ni_rctls;
187 	ra->ra_rs = rsa;
188 	ra->ra_rates = *rs;
189 	rssadapt_updatestats(ra);
190 
191 	/* pick initial rate */
192 	for (ra->ra_rix = rs->rs_nrates - 1;
193 	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
194 	     ra->ra_rix--)
195 		;
196 	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
197 	ra->ra_ticks = ticks;
198 
199 	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
200 	    "RSSADAPT initial rate %d", ni->ni_txrate);
201 }
202 
203 static void
204 rssadapt_node_deinit(struct ieee80211_node *ni)
205 {
206 
207 	kfree(ni->ni_rctls, M_80211_RATECTL);
208 }
209 
210 static __inline int
211 bucket(int pktlen)
212 {
213 	int i, top, thridx;
214 
215 	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
216 	     i < IEEE80211_RSSADAPT_BKTS;
217 	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
218 		thridx = i;
219 		if (pktlen <= top)
220 			break;
221 	}
222 	return thridx;
223 }
224 
225 static int
226 rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
227 {
228 	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
229 	u_int pktlen = iarg;
230 	const struct ieee80211_rateset *rs = &ra->ra_rates;
231 	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
232 	int rix, rssi;
233 
234 	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
235 		rssadapt_updatestats(ra);
236 		ra->ra_ticks = ticks;
237 	}
238 
239 	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
240 
241 	/* XXX this is average rssi, should be using last value */
242 	rssi = ni->ni_ic->ic_node_getrssi(ni);
243 	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
244 		if ((*thrs)[rix] < (rssi << 8))
245 			break;
246 	if (rix != ra->ra_rix) {
247 		/* update public rate */
248 		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
249 		ra->ra_rix = rix;
250 
251 		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
252 		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
253 		    ni->ni_txrate, pktlen, rssi);
254 	}
255 	return rix;
256 }
257 
258 /*
259  * Adapt the data rate to suit the conditions.  When a transmitted
260  * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
261  * raise the RSS threshold for transmitting packets of similar length at
262  * the same data rate.
263  */
264 static void
265 rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
266 {
267 	uint16_t last_thr;
268 	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
269 	u_int rix;
270 
271 	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
272 
273 	rix = ra->ra_rix;
274 	last_thr = (*thrs)[rix];
275 	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
276 	    last_thr, (rssi << 8));
277 
278 	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
279 	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
280 	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
281 	    last_thr, (*thrs)[rix], rssi);
282 }
283 
284 static void
285 rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
286 {
287 	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
288 	uint16_t newthr, oldthr;
289 	int rix;
290 
291 	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
292 
293 	rix = ra->ra_rix;
294 	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
295 		oldthr = (*thrs)[rix + 1];
296 		if ((*thrs)[rix] == 0)
297 			newthr = (rssi << 8);
298 		else
299 			newthr = (*thrs)[rix];
300 		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
301 		    oldthr, newthr);
302 
303 		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
304 		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
305 		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
306 		    oldthr, newthr, rssi);
307 
308 		ra->ra_last_raise = ticks;
309 	}
310 }
311 
312 static void
313 rssadapt_tx_complete(const struct ieee80211vap *vap,
314     const struct ieee80211_node *ni, int success, void *arg1, void *arg2)
315 {
316 	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
317 	int pktlen = *(int *)arg1, rssi = *(int *)arg2;
318 
319 	if (success) {
320 		ra->ra_nok++;
321 		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
322 		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
323 			rssadapt_raise_rate(ra, pktlen, rssi);
324 	} else {
325 		ra->ra_nfail++;
326 		rssadapt_lower_rate(ra, pktlen, rssi);
327 	}
328 }
329 
330 static int
331 rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
332 {
333 	struct ieee80211vap *vap = arg1;
334 	struct ieee80211_rssadapt *rs = vap->iv_rs;
335 	int msecs = ticks_to_msecs(rs->interval);
336 	int error;
337 
338 	error = sysctl_handle_int(oidp, &msecs, 0, req);
339 	if (error || !req->newptr)
340 		return error;
341 	rssadapt_setinterval(vap, msecs);
342 	return 0;
343 }
344 
345 static void
346 rssadapt_sysctlattach(struct ieee80211vap *vap,
347     struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
348 {
349 
350 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
351 	    "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
352 	    0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
353 }
354