ieee80211_rssadapt.c revision 321725 
1/*	$FreeBSD: stable/10/sys/net80211/ieee80211_rssadapt.c 321725 2017-07-30 18:38:05Z avos $	*/
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	nrefs++;		/* XXX locking */
132	vap->iv_rs = rs = malloc(sizeof(struct ieee80211_rssadapt),
133	    M_80211_RATECTL, M_NOWAIT|M_ZERO);
134	if (rs == NULL) {
135		if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
136		return;
137	}
138	rs->vap = vap;
139	rssadapt_setinterval(vap, 500 /* msecs */);
140	rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
141}
142
143static void
144rssadapt_deinit(struct ieee80211vap *vap)
145{
146	free(vap->iv_rs, M_80211_RATECTL);
147	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
148	nrefs--;		/* XXX locking */
149}
150
151static void
152rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
153{
154	long interval;
155
156	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
157	ra->ra_nfail = ra->ra_nok = 0;
158
159	/*
160	 * A node is eligible for its rate to be raised every 1/10 to 10
161	 * seconds, more eligible in proportion to recent packet rates.
162	 */
163	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
164	ra->ra_raise_interval = msecs_to_ticks(interval);
165}
166
167static void
168rssadapt_node_init(struct ieee80211_node *ni)
169{
170	struct ieee80211_rssadapt_node *ra;
171	struct ieee80211vap *vap = ni->ni_vap;
172	struct ieee80211_rssadapt *rsa = vap->iv_rs;
173	const struct ieee80211_rateset *rs = &ni->ni_rates;
174
175	if (ni->ni_rctls == NULL) {
176		ni->ni_rctls = ra =
177		    malloc(sizeof(struct ieee80211_rssadapt_node),
178		        M_80211_RATECTL, M_NOWAIT|M_ZERO);
179		if (ra == NULL) {
180			if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
181			    "structure\n");
182			return;
183		}
184	} else
185		ra = ni->ni_rctls;
186	ra->ra_rs = rsa;
187	ra->ra_rates = *rs;
188	rssadapt_updatestats(ra);
189
190	/* pick initial rate */
191	for (ra->ra_rix = rs->rs_nrates - 1;
192	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
193	     ra->ra_rix--)
194		;
195	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
196	ra->ra_ticks = ticks;
197
198	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
199	    "RSSADAPT initial rate %d", ni->ni_txrate);
200}
201
202static void
203rssadapt_node_deinit(struct ieee80211_node *ni)
204{
205
206	free(ni->ni_rctls, M_80211_RATECTL);
207}
208
209static __inline int
210bucket(int pktlen)
211{
212	int i, top, thridx;
213
214	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
215	     i < IEEE80211_RSSADAPT_BKTS;
216	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
217		thridx = i;
218		if (pktlen <= top)
219			break;
220	}
221	return thridx;
222}
223
224static int
225rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
226{
227	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
228	u_int pktlen = iarg;
229	const struct ieee80211_rateset *rs = &ra->ra_rates;
230	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
231	int rix, rssi;
232
233	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
234		rssadapt_updatestats(ra);
235		ra->ra_ticks = ticks;
236	}
237
238	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
239
240	/* XXX this is average rssi, should be using last value */
241	rssi = ni->ni_ic->ic_node_getrssi(ni);
242	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
243		if ((*thrs)[rix] < (rssi << 8))
244			break;
245	if (rix != ra->ra_rix) {
246		/* update public rate */
247		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
248		ra->ra_rix = rix;
249
250		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
251		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
252		    ni->ni_txrate, pktlen, rssi);
253	}
254	return rix;
255}
256
257/*
258 * Adapt the data rate to suit the conditions.  When a transmitted
259 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
260 * raise the RSS threshold for transmitting packets of similar length at
261 * the same data rate.
262 */
263static void
264rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
265{
266	uint16_t last_thr;
267	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
268	u_int rix;
269
270	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
271
272	rix = ra->ra_rix;
273	last_thr = (*thrs)[rix];
274	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
275	    last_thr, (rssi << 8));
276
277	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
278	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
279	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
280	    last_thr, (*thrs)[rix], rssi);
281}
282
283static void
284rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
285{
286	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
287	uint16_t newthr, oldthr;
288	int rix;
289
290	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
291
292	rix = ra->ra_rix;
293	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
294		oldthr = (*thrs)[rix + 1];
295		if ((*thrs)[rix] == 0)
296			newthr = (rssi << 8);
297		else
298			newthr = (*thrs)[rix];
299		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
300		    oldthr, newthr);
301
302		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
303		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
304		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
305		    oldthr, newthr, rssi);
306
307		ra->ra_last_raise = ticks;
308	}
309}
310
311static void
312rssadapt_tx_complete(const struct ieee80211vap *vap,
313    const struct ieee80211_node *ni, int success, void *arg1, void *arg2)
314{
315	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
316	int pktlen = *(int *)arg1, rssi = *(int *)arg2;
317
318	if (success) {
319		ra->ra_nok++;
320		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
321		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
322			rssadapt_raise_rate(ra, pktlen, rssi);
323	} else {
324		ra->ra_nfail++;
325		rssadapt_lower_rate(ra, pktlen, rssi);
326	}
327}
328
329static int
330rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
331{
332	struct ieee80211vap *vap = arg1;
333	struct ieee80211_rssadapt *rs = vap->iv_rs;
334	int msecs = ticks_to_msecs(rs->interval);
335	int error;
336
337	error = sysctl_handle_int(oidp, &msecs, 0, req);
338	if (error || !req->newptr)
339		return error;
340	rssadapt_setinterval(vap, msecs);
341	return 0;
342}
343
344static void
345rssadapt_sysctlattach(struct ieee80211vap *vap,
346    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
347{
348
349	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
350	    "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
351	    0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
352}
353