1 /*	$OpenBSD: ieee80211_amrr.c,v 1.1 2006/06/17 19:07:19 damien Exp $	*/
2 
3 /*-
4  * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
5  * Copyright (c) 2006
6  *	Damien Bergamini <damien.bergamini@free.fr>
7  *
8  * Permission to use, copy, modify, and distribute this software for any
9  * purpose with or without fee is hereby granted, provided that the above
10  * copyright notice and this permission notice appear in all copies.
11  *
12  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
13  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
18  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19  */
20 
21 #include <sys/cdefs.h>
22 __FBSDID("$FreeBSD$");
23 
24 /*-
25  * Naive implementation of the Adaptive Multi Rate Retry algorithm:
26  *
27  * "IEEE 802.11 Rate Adaptation: A Practical Approach"
28  *  Mathieu Lacage, Hossein Manshaei, Thierry Turletti
29  *  INRIA Sophia - Projet Planete
30  *  http://www-sop.inria.fr/rapports/sophia/RR-5208.html
31  */
32 #include "opt_wlan.h"
33 
34 #include <sys/param.h>
35 #include <sys/kernel.h>
36 #include <sys/module.h>
37 #include <sys/socket.h>
38 #include <sys/sysctl.h>
39 
40 #include <net/if.h>
41 #include <net/if_var.h>
42 #include <net/if_media.h>
43 #include <net/ethernet.h>
44 
45 #ifdef INET
46 #include <netinet/in.h>
47 #include <netinet/if_ether.h>
48 #endif
49 
50 #include <netproto/802_11/ieee80211_var.h>
51 #include <netproto/802_11/ieee80211_ht.h>
52 #include <netproto/802_11/ieee80211_amrr.h>
53 #include <netproto/802_11/ieee80211_ratectl.h>
54 
55 #define is_success(amn)	\
56 	((amn)->amn_retrycnt < (amn)->amn_txcnt / 10)
57 #define is_failure(amn)	\
58 	((amn)->amn_retrycnt > (amn)->amn_txcnt / 3)
59 #define is_enough(amn)		\
60 	((amn)->amn_txcnt > 10)
61 
62 static void	amrr_setinterval(const struct ieee80211vap *, int);
63 static void	amrr_init(struct ieee80211vap *);
64 static void	amrr_deinit(struct ieee80211vap *);
65 static void	amrr_node_init(struct ieee80211_node *);
66 static void	amrr_node_deinit(struct ieee80211_node *);
67 static int	amrr_update(struct ieee80211_amrr *,
68     			struct ieee80211_amrr_node *, struct ieee80211_node *);
69 static int	amrr_rate(struct ieee80211_node *, void *, uint32_t);
70 static void	amrr_tx_complete(const struct ieee80211vap *,
71     			const struct ieee80211_node *, int,
72 			void *, void *);
73 static void	amrr_tx_update(const struct ieee80211vap *vap,
74 			const struct ieee80211_node *, void *, void *, void *);
75 static void	amrr_sysctlattach(struct ieee80211vap *,
76 			struct sysctl_ctx_list *, struct sysctl_oid *);
77 
78 /* number of references from net80211 layer */
79 static	int nrefs = 0;
80 
81 static const struct ieee80211_ratectl amrr = {
82 	.ir_name	= "amrr",
83 	.ir_attach	= NULL,
84 	.ir_detach	= NULL,
85 	.ir_init	= amrr_init,
86 	.ir_deinit	= amrr_deinit,
87 	.ir_node_init	= amrr_node_init,
88 	.ir_node_deinit	= amrr_node_deinit,
89 	.ir_rate	= amrr_rate,
90 	.ir_tx_complete	= amrr_tx_complete,
91 	.ir_tx_update	= amrr_tx_update,
92 	.ir_setinterval	= amrr_setinterval,
93 };
94 IEEE80211_RATECTL_MODULE(amrr, 1);
95 IEEE80211_RATECTL_ALG(amrr, IEEE80211_RATECTL_AMRR, amrr);
96 
97 static void
98 amrr_setinterval(const struct ieee80211vap *vap, int msecs)
99 {
100 	struct ieee80211_amrr *amrr = vap->iv_rs;
101 	int t;
102 
103 	if (msecs < 100)
104 		msecs = 100;
105 	t = msecs_to_ticks(msecs);
106 	amrr->amrr_interval = (t < 1) ? 1 : t;
107 }
108 
109 static void
110 amrr_init(struct ieee80211vap *vap)
111 {
112 	struct ieee80211_amrr *amrr;
113 
114 	KASSERT(vap->iv_rs == NULL, ("%s called multiple times", __func__));
115 
116 	amrr = vap->iv_rs = kmalloc(sizeof(struct ieee80211_amrr),
117 	    M_80211_RATECTL, M_INTWAIT|M_ZERO);
118 	if (amrr == NULL) {
119 		if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
120 		return;
121 	}
122 	amrr->amrr_min_success_threshold = IEEE80211_AMRR_MIN_SUCCESS_THRESHOLD;
123 	amrr->amrr_max_success_threshold = IEEE80211_AMRR_MAX_SUCCESS_THRESHOLD;
124 	amrr_setinterval(vap, 500 /* ms */);
125 	amrr_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
126 }
127 
128 static void
129 amrr_deinit(struct ieee80211vap *vap)
130 {
131 	kfree(vap->iv_rs, M_80211_RATECTL);
132 }
133 
134 /*
135  * Return whether 11n rates are possible.
136  *
137  * Some 11n devices may return HT information but no HT rates.
138  * Thus, we shouldn't treat them as an 11n node.
139  */
140 static int
141 amrr_node_is_11n(struct ieee80211_node *ni)
142 {
143 
144 	if (ni->ni_chan == NULL)
145 		return (0);
146 	if (ni->ni_chan == IEEE80211_CHAN_ANYC)
147 		return (0);
148 	if (IEEE80211_IS_CHAN_HT(ni->ni_chan) && ni->ni_htrates.rs_nrates == 0)
149 		return (0);
150 	return (IEEE80211_IS_CHAN_HT(ni->ni_chan));
151 }
152 
153 static void
154 amrr_node_init(struct ieee80211_node *ni)
155 {
156 	const struct ieee80211_rateset *rs = NULL;
157 	struct ieee80211vap *vap = ni->ni_vap;
158 	struct ieee80211_amrr *amrr = vap->iv_rs;
159 	struct ieee80211_amrr_node *amn;
160 	uint8_t rate;
161 
162 	if (ni->ni_rctls == NULL) {
163 		ni->ni_rctls = amn = kmalloc(sizeof(struct ieee80211_amrr_node),
164 		    M_80211_RATECTL, M_INTWAIT|M_ZERO);
165 		if (amn == NULL) {
166 			if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
167 			    "structure\n");
168 			return;
169 		}
170 	} else
171 		amn = ni->ni_rctls;
172 	amn->amn_amrr = amrr;
173 	amn->amn_success = 0;
174 	amn->amn_recovery = 0;
175 	amn->amn_txcnt = amn->amn_retrycnt = 0;
176 	amn->amn_success_threshold = amrr->amrr_min_success_threshold;
177 
178 	/* 11n or not? Pick the right rateset */
179 	if (amrr_node_is_11n(ni)) {
180 		/* XXX ew */
181 		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
182 		    "%s: 11n node", __func__);
183 		rs = (struct ieee80211_rateset *) &ni->ni_htrates;
184 	} else {
185 		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
186 		    "%s: non-11n node", __func__);
187 		rs = &ni->ni_rates;
188 	}
189 
190 	/* Initial rate - lowest */
191 	rate = rs->rs_rates[0];
192 
193 	/* XXX clear the basic rate flag if it's not 11n */
194 	if (! amrr_node_is_11n(ni))
195 		rate &= IEEE80211_RATE_VAL;
196 
197 	/* pick initial rate from the rateset - HT or otherwise */
198 	/* Pick something low that's likely to succeed */
199 	for (amn->amn_rix = rs->rs_nrates - 1; amn->amn_rix > 0;
200 	    amn->amn_rix--) {
201 		/* legacy - anything < 36mbit, stop searching */
202 		/* 11n - stop at MCS4 */
203 		if (amrr_node_is_11n(ni)) {
204 			if ((rs->rs_rates[amn->amn_rix] & 0x1f) < 4)
205 				break;
206 		} else if ((rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL) <= 72)
207 			break;
208 	}
209 	rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
210 
211 	/* if the rate is an 11n rate, ensure the MCS bit is set */
212 	if (amrr_node_is_11n(ni))
213 		rate |= IEEE80211_RATE_MCS;
214 
215 	/* Assign initial rate from the rateset */
216 	ni->ni_txrate = rate;
217 	amn->amn_ticks = ticks;
218 
219 	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
220 	    "AMRR: nrates=%d, initial rate %d",
221 	    rs->rs_nrates,
222 	    rate);
223 }
224 
225 static void
226 amrr_node_deinit(struct ieee80211_node *ni)
227 {
228 	kfree(ni->ni_rctls, M_80211_RATECTL);
229 }
230 
231 static int
232 amrr_update(struct ieee80211_amrr *amrr, struct ieee80211_amrr_node *amn,
233     struct ieee80211_node *ni)
234 {
235 	int rix = amn->amn_rix;
236 	const struct ieee80211_rateset *rs = NULL;
237 
238 	KASSERT(is_enough(amn), ("txcnt %d", amn->amn_txcnt));
239 
240 	/* 11n or not? Pick the right rateset */
241 	if (amrr_node_is_11n(ni)) {
242 		/* XXX ew */
243 		rs = (struct ieee80211_rateset *) &ni->ni_htrates;
244 	} else {
245 		rs = &ni->ni_rates;
246 	}
247 
248 	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
249 	    "AMRR: current rate %d, txcnt=%d, retrycnt=%d",
250 	    rs->rs_rates[rix] & IEEE80211_RATE_VAL,
251 	    amn->amn_txcnt,
252 	    amn->amn_retrycnt);
253 
254 	/*
255 	 * XXX This is totally bogus for 11n, as although high MCS
256 	 * rates for each stream may be failing, the next stream
257 	 * should be checked.
258 	 *
259 	 * Eg, if MCS5 is ok but MCS6/7 isn't, and we can go up to
260 	 * MCS23, we should skip 6/7 and try 8 onwards.
261 	 */
262 	if (is_success(amn)) {
263 		amn->amn_success++;
264 		if (amn->amn_success >= amn->amn_success_threshold &&
265 		    rix + 1 < rs->rs_nrates) {
266 			amn->amn_recovery = 1;
267 			amn->amn_success = 0;
268 			rix++;
269 			IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
270 			    "AMRR increasing rate %d (txcnt=%d retrycnt=%d)",
271 			    rs->rs_rates[rix] & IEEE80211_RATE_VAL,
272 			    amn->amn_txcnt, amn->amn_retrycnt);
273 		} else {
274 			amn->amn_recovery = 0;
275 		}
276 	} else if (is_failure(amn)) {
277 		amn->amn_success = 0;
278 		if (rix > 0) {
279 			if (amn->amn_recovery) {
280 				amn->amn_success_threshold *= 2;
281 				if (amn->amn_success_threshold >
282 				    amrr->amrr_max_success_threshold)
283 					amn->amn_success_threshold =
284 					    amrr->amrr_max_success_threshold;
285 			} else {
286 				amn->amn_success_threshold =
287 				    amrr->amrr_min_success_threshold;
288 			}
289 			rix--;
290 			IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
291 			    "AMRR decreasing rate %d (txcnt=%d retrycnt=%d)",
292 			    rs->rs_rates[rix] & IEEE80211_RATE_VAL,
293 			    amn->amn_txcnt, amn->amn_retrycnt);
294 		}
295 		amn->amn_recovery = 0;
296 	}
297 
298 	/* reset counters */
299 	amn->amn_txcnt = 0;
300 	amn->amn_retrycnt = 0;
301 
302 	return rix;
303 }
304 
305 /*
306  * Return the rate index to use in sending a data frame.
307  * Update our internal state if it's been long enough.
308  * If the rate changes we also update ni_txrate to match.
309  */
310 static int
311 amrr_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg __unused)
312 {
313 	struct ieee80211_amrr_node *amn = ni->ni_rctls;
314 	struct ieee80211_amrr *amrr = amn->amn_amrr;
315 	const struct ieee80211_rateset *rs = NULL;
316 	int rix;
317 
318 	/* 11n or not? Pick the right rateset */
319 	if (amrr_node_is_11n(ni)) {
320 		/* XXX ew */
321 		rs = (struct ieee80211_rateset *) &ni->ni_htrates;
322 	} else {
323 		rs = &ni->ni_rates;
324 	}
325 
326 	if (is_enough(amn) && (ticks - amn->amn_ticks) > amrr->amrr_interval) {
327 		rix = amrr_update(amrr, amn, ni);
328 		if (rix != amn->amn_rix) {
329 			/* update public rate */
330 			ni->ni_txrate = rs->rs_rates[rix];
331 			/* XXX strip basic rate flag from txrate, if non-11n */
332 			if (amrr_node_is_11n(ni))
333 				ni->ni_txrate |= IEEE80211_RATE_MCS;
334 			else
335 				ni->ni_txrate &= IEEE80211_RATE_VAL;
336 			amn->amn_rix = rix;
337 		}
338 		amn->amn_ticks = ticks;
339 	} else
340 		rix = amn->amn_rix;
341 	return rix;
342 }
343 
344 /*
345  * Update statistics with tx complete status.  Ok is non-zero
346  * if the packet is known to be ACK'd.  Retries has the number
347  * retransmissions (i.e. xmit attempts - 1).
348  */
349 static void
350 amrr_tx_complete(const struct ieee80211vap *vap,
351     const struct ieee80211_node *ni, int ok,
352     void *arg1, void *arg2 __unused)
353 {
354 	struct ieee80211_amrr_node *amn = ni->ni_rctls;
355 	int retries = *(int *)arg1;
356 
357 	amn->amn_txcnt++;
358 	if (ok)
359 		amn->amn_success++;
360 	amn->amn_retrycnt += retries;
361 }
362 
363 /*
364  * Set tx count/retry statistics explicitly.  Intended for
365  * drivers that poll the device for statistics maintained
366  * in the device.
367  */
368 static void
369 amrr_tx_update(const struct ieee80211vap *vap, const struct ieee80211_node *ni,
370     void *arg1, void *arg2, void *arg3)
371 {
372 	struct ieee80211_amrr_node *amn = ni->ni_rctls;
373 	int txcnt = *(int *)arg1, success = *(int *)arg2, retrycnt = *(int *)arg3;
374 
375 	amn->amn_txcnt = txcnt;
376 	amn->amn_success = success;
377 	amn->amn_retrycnt = retrycnt;
378 }
379 
380 static int
381 amrr_sysctl_interval(SYSCTL_HANDLER_ARGS)
382 {
383 	struct ieee80211vap *vap = arg1;
384 	struct ieee80211_amrr *amrr = vap->iv_rs;
385 	int msecs = ticks_to_msecs(amrr->amrr_interval);
386 	int error;
387 
388 	error = sysctl_handle_int(oidp, &msecs, 0, req);
389 	if (error || !req->newptr)
390 		return error;
391 	amrr_setinterval(vap, msecs);
392 	return 0;
393 }
394 
395 static void
396 amrr_sysctlattach(struct ieee80211vap *vap,
397     struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
398 {
399 	struct ieee80211_amrr *amrr = vap->iv_rs;
400 
401 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
402 	    "amrr_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
403 	    0, amrr_sysctl_interval, "I", "amrr operation interval (ms)");
404 	/* XXX bounds check values */
405 	SYSCTL_ADD_UINT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
406 	    "amrr_max_sucess_threshold", CTLFLAG_RW,
407 	    &amrr->amrr_max_success_threshold, 0, "");
408 	SYSCTL_ADD_UINT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
409 	    "amrr_min_sucess_threshold", CTLFLAG_RW,
410 	    &amrr->amrr_min_success_threshold, 0, "");
411 }
412