ieee80211_rssadapt.c revision 206358 
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 <net80211/ieee80211_var.h>
45#include <net80211/ieee80211_rssadapt.h>
46#include <net80211/ieee80211_ratectl.h>
47
48struct 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
60static 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
76static void	rssadapt_setinterval(const struct ieee80211vap *, int);
77static void	rssadapt_init(struct ieee80211vap *);
78static void	rssadapt_deinit(struct ieee80211vap *);
79static void	rssadapt_updatestats(struct ieee80211_rssadapt_node *);
80static void	rssadapt_node_init(struct ieee80211_node *);
81static void	rssadapt_node_deinit(struct ieee80211_node *);
82static int	rssadapt_rate(struct ieee80211_node *, void *, uint32_t);
83static void	rssadapt_lower_rate(struct ieee80211_rssadapt_node *, int, int);
84static void	rssadapt_raise_rate(struct ieee80211_rssadapt_node *,
85			int, int);
86static void	rssadapt_tx_complete(const struct ieee80211vap *,
87    			const struct ieee80211_node *, int,
88			void *, void *);
89static void	rssadapt_sysctlattach(struct ieee80211vap *,
90			struct sysctl_ctx_list *, struct sysctl_oid *);
91
92/* number of references from net80211 layer */
93static	int nrefs = 0;
94
95static 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};
108IEEE80211_RATECTL_MODULE(rssadapt, 1);
109IEEE80211_RATECTL_ALG(rssadapt, IEEE80211_RATECTL_RSSADAPT, rssadapt);
110
111static void
112rssadapt_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
123static void
124rssadapt_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 = malloc(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
139static void
140rssadapt_deinit(struct ieee80211vap *vap)
141{
142	free(vap->iv_rs, M_80211_RATECTL);
143}
144
145static void
146rssadapt_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
161static void
162rssadapt_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	ra = malloc(sizeof(struct ieee80211_rssadapt_node), M_80211_RATECTL,
169	    M_WAITOK|M_ZERO);
170	ni->ni_rctls = ra;
171	ra->ra_rs = rsa;
172	ra->ra_rates = *rs;
173	rssadapt_updatestats(ra);
174
175	/* pick initial rate */
176	for (ra->ra_rix = rs->rs_nrates - 1;
177	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
178	     ra->ra_rix--)
179		;
180	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
181	ra->ra_ticks = ticks;
182
183	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
184	    "RSSADAPT initial rate %d", ni->ni_txrate);
185}
186
187static void
188rssadapt_node_deinit(struct ieee80211_node *ni)
189{
190
191	free(ni->ni_rctls, M_80211_RATECTL);
192}
193
194static __inline int
195bucket(int pktlen)
196{
197	int i, top, thridx;
198
199	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
200	     i < IEEE80211_RSSADAPT_BKTS;
201	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
202		thridx = i;
203		if (pktlen <= top)
204			break;
205	}
206	return thridx;
207}
208
209static int
210rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
211{
212	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
213	u_int pktlen = iarg;
214	const struct ieee80211_rateset *rs = &ra->ra_rates;
215	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
216	int rix, rssi;
217
218	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
219		rssadapt_updatestats(ra);
220		ra->ra_ticks = ticks;
221	}
222
223	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
224
225	/* XXX this is average rssi, should be using last value */
226	rssi = ni->ni_ic->ic_node_getrssi(ni);
227	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
228		if ((*thrs)[rix] < (rssi << 8))
229			break;
230	if (rix != ra->ra_rix) {
231		/* update public rate */
232		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
233		ra->ra_rix = rix;
234
235		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
236		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
237		    ni->ni_txrate, pktlen, rssi);
238	}
239	return rix;
240}
241
242/*
243 * Adapt the data rate to suit the conditions.  When a transmitted
244 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
245 * raise the RSS threshold for transmitting packets of similar length at
246 * the same data rate.
247 */
248static void
249rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
250{
251	uint16_t last_thr;
252	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
253	u_int rix;
254
255	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
256
257	rix = ra->ra_rix;
258	last_thr = (*thrs)[rix];
259	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
260	    last_thr, (rssi << 8));
261
262	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
263	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
264	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
265	    last_thr, (*thrs)[rix], rssi);
266}
267
268static void
269rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
270{
271	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
272	uint16_t newthr, oldthr;
273	int rix;
274
275	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
276
277	rix = ra->ra_rix;
278	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
279		oldthr = (*thrs)[rix + 1];
280		if ((*thrs)[rix] == 0)
281			newthr = (rssi << 8);
282		else
283			newthr = (*thrs)[rix];
284		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
285		    oldthr, newthr);
286
287		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
288		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
289		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
290		    oldthr, newthr, rssi);
291
292		ra->ra_last_raise = ticks;
293	}
294}
295
296static void
297rssadapt_tx_complete(const struct ieee80211vap *vap,
298    const struct ieee80211_node *ni, int success, void *arg1, void *arg2)
299{
300	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
301	int pktlen = *(int *)arg1, rssi = *(int *)arg2;
302
303	if (success) {
304		ra->ra_nok++;
305		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
306		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
307			rssadapt_raise_rate(ra, pktlen, rssi);
308	} else {
309		ra->ra_nfail++;
310		rssadapt_lower_rate(ra, pktlen, rssi);
311	}
312}
313
314static int
315rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
316{
317	struct ieee80211vap *vap = arg1;
318	struct ieee80211_rssadapt *rs = vap->iv_rs;
319	int msecs = ticks_to_msecs(rs->interval);
320	int error;
321
322	error = sysctl_handle_int(oidp, &msecs, 0, req);
323	if (error || !req->newptr)
324		return error;
325	rssadapt_setinterval(vap, msecs);
326	return 0;
327}
328
329static void
330rssadapt_sysctlattach(struct ieee80211vap *vap,
331    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
332{
333
334	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
335	    "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
336	    0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
337}
338