1/* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
2/*-
3 * SPDX-License-Identifier: BSD-3-Clause
4 *
5 * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
6 * Copyright (c) 2003, 2004 David Young.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or
9 * without modification, are permitted provided that the following
10 * conditions are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above
14 *    copyright notice, this list of conditions and the following
15 *    disclaimer in the documentation and/or other materials provided
16 *    with the distribution.
17 * 3. The name of David Young may not be used to endorse or promote
18 *    products derived from this software without specific prior
19 *    written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
22 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
23 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
24 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
25 * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
27 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
29 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
32 * OF SUCH DAMAGE.
33 */
34#include "opt_wlan.h"
35
36#include <sys/param.h>
37#include <sys/systm.h>
38#include <sys/kernel.h>
39#include <sys/malloc.h>
40#include <sys/module.h>
41#include <sys/socket.h>
42#include <sys/sysctl.h>
43
44#include <net/if.h>
45#include <net/if_var.h>
46#include <net/if_media.h>
47#include <net/ethernet.h>
48
49#include <net80211/ieee80211_var.h>
50#include <net80211/ieee80211_rssadapt.h>
51#include <net80211/ieee80211_ratectl.h>
52
53struct rssadapt_expavgctl {
54	/* RSS threshold decay. */
55	u_int rc_decay_denom;
56	u_int rc_decay_old;
57	/* RSS threshold update. */
58	u_int rc_thresh_denom;
59	u_int rc_thresh_old;
60	/* RSS average update. */
61	u_int rc_avgrssi_denom;
62	u_int rc_avgrssi_old;
63};
64
65static struct rssadapt_expavgctl master_expavgctl = {
66	.rc_decay_denom = 16,
67	.rc_decay_old = 15,
68	.rc_thresh_denom = 8,
69	.rc_thresh_old = 4,
70	.rc_avgrssi_denom = 8,
71	.rc_avgrssi_old = 4
72};
73
74#ifdef interpolate
75#undef interpolate
76#endif
77#define interpolate(parm, old, new) ((parm##_old * (old) + \
78                                     (parm##_denom - parm##_old) * (new)) / \
79				    parm##_denom)
80
81static void	rssadapt_setinterval(const struct ieee80211vap *, int);
82static void	rssadapt_init(struct ieee80211vap *);
83static void	rssadapt_deinit(struct ieee80211vap *);
84static void	rssadapt_updatestats(struct ieee80211_rssadapt_node *);
85static void	rssadapt_node_init(struct ieee80211_node *);
86static void	rssadapt_node_deinit(struct ieee80211_node *);
87static int	rssadapt_rate(struct ieee80211_node *, void *, uint32_t);
88static void	rssadapt_lower_rate(struct ieee80211_rssadapt_node *, int, int);
89static void	rssadapt_raise_rate(struct ieee80211_rssadapt_node *,
90			int, int);
91static void	rssadapt_tx_complete(const struct ieee80211_node *,
92			const struct ieee80211_ratectl_tx_status *);
93static void	rssadapt_sysctlattach(struct ieee80211vap *,
94			struct sysctl_ctx_list *, struct sysctl_oid *);
95
96/* number of references from net80211 layer */
97static	int nrefs = 0;
98
99static 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};
112IEEE80211_RATECTL_MODULE(rssadapt, 1);
113IEEE80211_RATECTL_ALG(rssadapt, IEEE80211_RATECTL_RSSADAPT, rssadapt);
114
115static void
116rssadapt_setinterval(const struct ieee80211vap *vap, int msecs)
117{
118	struct ieee80211_rssadapt *rs = vap->iv_rs;
119
120	if (!rs)
121		return;
122
123	if (msecs < 100)
124		msecs = 100;
125	rs->interval = msecs_to_ticks(msecs);
126}
127
128static void
129rssadapt_init(struct ieee80211vap *vap)
130{
131	struct ieee80211_rssadapt *rs;
132
133	KASSERT(vap->iv_rs == NULL, ("%s: iv_rs already initialized",
134	    __func__));
135
136	nrefs++;		/* XXX locking */
137	vap->iv_rs = rs = IEEE80211_MALLOC(sizeof(struct ieee80211_rssadapt),
138	    M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
139	if (rs == NULL) {
140		if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
141		return;
142	}
143	rs->vap = vap;
144	rssadapt_setinterval(vap, 500 /* msecs */);
145	rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
146}
147
148static void
149rssadapt_deinit(struct ieee80211vap *vap)
150{
151	IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
152	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
153	nrefs--;		/* XXX locking */
154}
155
156static void
157rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
158{
159	long interval;
160
161	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
162	ra->ra_nfail = ra->ra_nok = 0;
163
164	/*
165	 * A node is eligible for its rate to be raised every 1/10 to 10
166	 * seconds, more eligible in proportion to recent packet rates.
167	 */
168	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
169	ra->ra_raise_interval = msecs_to_ticks(interval);
170}
171
172static void
173rssadapt_node_init(struct ieee80211_node *ni)
174{
175	struct ieee80211_rssadapt_node *ra;
176	struct ieee80211vap *vap = ni->ni_vap;
177	struct ieee80211_rssadapt *rsa = vap->iv_rs;
178	const struct ieee80211_rateset *rs = &ni->ni_rates;
179
180	if (!rsa) {
181		if_printf(vap->iv_ifp, "ratectl structure was not allocated, "
182		    "per-node structure allocation skipped\n");
183		return;
184	}
185
186	if (ni->ni_rctls == NULL) {
187		ni->ni_rctls = ra =
188		    IEEE80211_MALLOC(sizeof(struct ieee80211_rssadapt_node),
189		        M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
190		if (ra == NULL) {
191			if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
192			    "structure\n");
193			return;
194		}
195	} else
196		ra = ni->ni_rctls;
197	ra->ra_rs = rsa;
198	ra->ra_rates = *rs;
199	rssadapt_updatestats(ra);
200
201	/* pick initial rate */
202	for (ra->ra_rix = rs->rs_nrates - 1;
203	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
204	     ra->ra_rix--)
205		;
206	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
207	ra->ra_ticks = ticks;
208
209	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
210	    "RSSADAPT initial rate %d", ni->ni_txrate);
211}
212
213static void
214rssadapt_node_deinit(struct ieee80211_node *ni)
215{
216
217	IEEE80211_FREE(ni->ni_rctls, M_80211_RATECTL);
218}
219
220static __inline int
221bucket(int pktlen)
222{
223	int i, top, thridx;
224
225	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
226	     i < IEEE80211_RSSADAPT_BKTS;
227	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
228		thridx = i;
229		if (pktlen <= top)
230			break;
231	}
232	return thridx;
233}
234
235static int
236rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
237{
238	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
239	u_int pktlen = iarg;
240	const struct ieee80211_rateset *rs;
241	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
242	int rix, rssi;
243
244	/* XXX should return -1 here, but drivers may not expect this... */
245	if (!ra)
246	{
247		ni->ni_txrate = ni->ni_rates.rs_rates[0];
248		return 0;
249	}
250
251	rs = &ra->ra_rates;
252	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
253		rssadapt_updatestats(ra);
254		ra->ra_ticks = ticks;
255	}
256
257	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
258
259	/* XXX this is average rssi, should be using last value */
260	rssi = ni->ni_ic->ic_node_getrssi(ni);
261	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
262		if ((*thrs)[rix] < (rssi << 8))
263			break;
264	if (rix != ra->ra_rix) {
265		/* update public rate */
266		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
267		ra->ra_rix = rix;
268
269		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
270		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
271		    ni->ni_txrate, pktlen, rssi);
272	}
273	return rix;
274}
275
276/*
277 * Adapt the data rate to suit the conditions.  When a transmitted
278 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
279 * raise the RSS threshold for transmitting packets of similar length at
280 * the same data rate.
281 */
282static void
283rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
284{
285	uint16_t last_thr;
286	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
287	u_int rix;
288
289	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
290
291	rix = ra->ra_rix;
292	last_thr = (*thrs)[rix];
293	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
294	    last_thr, (rssi << 8));
295
296	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
297	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
298	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
299	    last_thr, (*thrs)[rix], rssi);
300}
301
302static void
303rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
304{
305	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
306	uint16_t newthr, oldthr;
307	int rix;
308
309	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
310
311	rix = ra->ra_rix;
312	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
313		oldthr = (*thrs)[rix + 1];
314		if ((*thrs)[rix] == 0)
315			newthr = (rssi << 8);
316		else
317			newthr = (*thrs)[rix];
318		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
319		    oldthr, newthr);
320
321		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
322		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
323		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
324		    oldthr, newthr, rssi);
325
326		ra->ra_last_raise = ticks;
327	}
328}
329
330static void
331rssadapt_tx_complete(const struct ieee80211_node *ni,
332    const struct ieee80211_ratectl_tx_status *status)
333{
334	struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
335	int pktlen, rssi;
336
337	if (!ra)
338		return;
339
340	if ((status->flags &
341	    (IEEE80211_RATECTL_STATUS_PKTLEN|IEEE80211_RATECTL_STATUS_RSSI)) !=
342	    (IEEE80211_RATECTL_STATUS_PKTLEN|IEEE80211_RATECTL_STATUS_RSSI))
343		return;
344
345	pktlen = status->pktlen;
346	rssi = status->rssi;
347
348	if (status->status == IEEE80211_RATECTL_TX_SUCCESS) {
349		ra->ra_nok++;
350		if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
351		    (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
352			rssadapt_raise_rate(ra, pktlen, rssi);
353	} else {
354		ra->ra_nfail++;
355		rssadapt_lower_rate(ra, pktlen, rssi);
356	}
357}
358
359static int
360rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
361{
362	struct ieee80211vap *vap = arg1;
363	struct ieee80211_rssadapt *rs = vap->iv_rs;
364	int msecs, error;
365
366	if (!rs)
367		return ENOMEM;
368
369	msecs = ticks_to_msecs(rs->interval);
370	error = sysctl_handle_int(oidp, &msecs, 0, req);
371	if (error || !req->newptr)
372		return error;
373	rssadapt_setinterval(vap, msecs);
374	return 0;
375}
376
377static void
378rssadapt_sysctlattach(struct ieee80211vap *vap,
379    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
380{
381
382	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
383	    "rssadapt_rate_interval",
384	    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, vap, 0,
385	    rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
386}
387