1 /* $FreeBSD: src/sys/net80211/ieee80211_rssadapt.c,v 1.1 2008/04/20 20:35:44 sam Exp $ */
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
46 struct 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
58 static 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
74 static 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 */
78 static int nrefs = 0;
79
80 void
81 ieee80211_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
91 void
92 ieee80211_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
100 void
101 ieee80211_rssadapt_cleanup(struct ieee80211_rssadapt *rs)
102 {
103 }
104
105 static void
106 rssadapt_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
121 void
122 ieee80211_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
143 static __inline int
144 bucket(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
158 int
159 ieee80211_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 */
196 void
197 ieee80211_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
217 void
218 ieee80211_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
246 static int
247 rssadapt_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
260 static void
261 rssadapt_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 */
273 IEEE80211_RATE_MODULE(rssadapt, 1);
274
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