ieee80211_rssadapt.c revision 178354 
1/*	$FreeBSD: head/sys/net80211/ieee80211_rssadapt.c 178354 2008-04-20 20:35:46Z sam $	*/
2/* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
3/*-
4 * Copyright (c) 2003, 2004 David Young.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or
7 * without modification, are permitted provided that the following
8 * conditions are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above
12 *    copyright notice, this list of conditions and the following
13 *    disclaimer in the documentation and/or other materials provided
14 *    with the distribution.
15 * 3. The name of David Young may not be used to endorse or promote
16 *    products derived from this software without specific prior
17 *    written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
20 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
22 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
23 * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
25 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
27 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
28 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
30 * OF SUCH DAMAGE.
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_media.h>
42
43#include <net80211/ieee80211_var.h>
44#include <net80211/ieee80211_rssadapt.h>
45
46struct rssadapt_expavgctl {
47	/* RSS threshold decay. */
48	u_int rc_decay_denom;
49	u_int rc_decay_old;
50	/* RSS threshold update. */
51	u_int rc_thresh_denom;
52	u_int rc_thresh_old;
53	/* RSS average update. */
54	u_int rc_avgrssi_denom;
55	u_int rc_avgrssi_old;
56};
57
58static struct rssadapt_expavgctl master_expavgctl = {
59	rc_decay_denom : 16,
60	rc_decay_old : 15,
61	rc_thresh_denom : 8,
62	rc_thresh_old : 4,
63	rc_avgrssi_denom : 8,
64	rc_avgrssi_old : 4
65};
66
67#ifdef interpolate
68#undef interpolate
69#endif
70#define interpolate(parm, old, new) ((parm##_old * (old) + \
71                                     (parm##_denom - parm##_old) * (new)) / \
72				    parm##_denom)
73
74static void rssadapt_sysctlattach(struct ieee80211_rssadapt *rs,
75	struct sysctl_ctx_list *ctx, struct sysctl_oid *tree);
76
77/* number of references from net80211 layer */
78static	int nrefs = 0;
79
80void
81ieee80211_rssadapt_setinterval(struct ieee80211_rssadapt *rs, int msecs)
82{
83	int t;
84
85	if (msecs < 100)
86		msecs = 100;
87	t = msecs_to_ticks(msecs);
88	rs->interval = (t < 1) ? 1 : t;
89}
90
91void
92ieee80211_rssadapt_init(struct ieee80211_rssadapt *rs, struct ieee80211vap *vap, int interval)
93{
94	rs->vap = vap;
95	ieee80211_rssadapt_setinterval(rs, interval);
96
97	rssadapt_sysctlattach(rs, vap->iv_sysctl, vap->iv_oid);
98}
99
100void
101ieee80211_rssadapt_cleanup(struct ieee80211_rssadapt *rs)
102{
103}
104
105static void
106rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
107{
108	long interval;
109
110	ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
111	ra->ra_nfail = ra->ra_nok = 0;
112
113	/*
114	 * A node is eligible for its rate to be raised every 1/10 to 10
115	 * seconds, more eligible in proportion to recent packet rates.
116	 */
117	interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
118	ra->ra_raise_interval = msecs_to_ticks(interval);
119}
120
121void
122ieee80211_rssadapt_node_init(struct ieee80211_rssadapt *rsa,
123    struct ieee80211_rssadapt_node *ra, struct ieee80211_node *ni)
124{
125	const struct ieee80211_rateset *rs = &ni->ni_rates;
126
127	ra->ra_rs = rsa;
128	ra->ra_rates = *rs;
129	rssadapt_updatestats(ra);
130
131	/* pick initial rate */
132	for (ra->ra_rix = rs->rs_nrates - 1;
133	     ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
134	     ra->ra_rix--)
135		;
136	ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
137	ra->ra_ticks = ticks;
138
139	IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
140	    "RSSADAPT initial rate %d", ni->ni_txrate);
141}
142
143static __inline int
144bucket(int pktlen)
145{
146	int i, top, thridx;
147
148	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
149	     i < IEEE80211_RSSADAPT_BKTS;
150	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
151		thridx = i;
152		if (pktlen <= top)
153			break;
154	}
155	return thridx;
156}
157
158int
159ieee80211_rssadapt_choose(struct ieee80211_node *ni,
160    struct ieee80211_rssadapt_node *ra, u_int pktlen)
161{
162	const struct ieee80211_rateset *rs = &ra->ra_rates;
163	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
164	int rix, rssi;
165
166	if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
167		rssadapt_updatestats(ra);
168		ra->ra_ticks = ticks;
169	}
170
171	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
172
173	/* XXX this is average rssi, should be using last value */
174	rssi = ni->ni_ic->ic_node_getrssi(ni);
175	for (rix = rs->rs_nrates-1; rix >= 0; rix--)
176		if ((*thrs)[rix] < (rssi << 8))
177			break;
178	if (rix != ra->ra_rix) {
179		/* update public rate */
180		ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
181		ra->ra_rix = rix;
182
183		IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
184		    "RSSADAPT new rate %d (pktlen %d rssi %d)",
185		    ni->ni_txrate, pktlen, rssi);
186	}
187	return rix;
188}
189
190/*
191 * Adapt the data rate to suit the conditions.  When a transmitted
192 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
193 * raise the RSS threshold for transmitting packets of similar length at
194 * the same data rate.
195 */
196void
197ieee80211_rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra,
198    int pktlen, int rssi)
199{
200	uint16_t last_thr;
201	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
202	u_int rix;
203
204	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
205
206	rix = ra->ra_rix;
207	last_thr = (*thrs)[rix];
208	(*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
209	    last_thr, (rssi << 8));
210
211	IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
212	    "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
213	    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
214	    last_thr, (*thrs)[rix], rssi);
215}
216
217void
218ieee80211_rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra,
219    int pktlen, int rssi)
220{
221	uint16_t (*thrs)[IEEE80211_RATE_SIZE];
222	uint16_t newthr, oldthr;
223	int rix;
224
225	thrs = &ra->ra_rate_thresh[bucket(pktlen)];
226
227	rix = ra->ra_rix;
228	if ((*thrs)[rix + 1] > (*thrs)[rix]) {
229		oldthr = (*thrs)[rix + 1];
230		if ((*thrs)[rix] == 0)
231			newthr = (rssi << 8);
232		else
233			newthr = (*thrs)[rix];
234		(*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
235		    oldthr, newthr);
236
237		IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
238		    "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
239		    ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
240		    oldthr, newthr, rssi);
241
242		ra->ra_last_raise = ticks;
243	}
244}
245
246static int
247rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
248{
249	struct ieee80211_rssadapt *rs = arg1;
250	int msecs = ticks_to_msecs(rs->interval);
251	int error;
252
253	error = sysctl_handle_int(oidp, &msecs, 0, req);
254	if (error || !req->newptr)
255		return error;
256	ieee80211_rssadapt_setinterval(rs, msecs);
257	return 0;
258}
259
260static void
261rssadapt_sysctlattach(struct ieee80211_rssadapt *rs,
262    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
263{
264
265	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
266	    "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, rs,
267	    0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
268}
269
270/*
271 * Module glue.
272 */
273IEEE80211_RATE_MODULE(rssadapt, 1);
274