ieee80211_amrr.c revision 164633 
1/*	$OpenBSD: ieee80211_amrr.c,v 1.1 2006/06/17 19:07:19 damien Exp $	*/
2
3/*-
4 * Copyright (c) 2006
5 *	Damien Bergamini <damien.bergamini@free.fr>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#include <sys/cdefs.h>
21__FBSDID("$FreeBSD: head/sys/net80211/ieee80211_amrr.c 164633 2006-11-26 19:55:26Z sam $");
22
23/*-
24 * Naive implementation of the Adaptive Multi Rate Retry algorithm:
25 *
26 * "IEEE 802.11 Rate Adaptation: A Practical Approach"
27 *  Mathieu Lacage, Hossein Manshaei, Thierry Turletti
28 *  INRIA Sophia - Projet Planete
29 *  http://www-sop.inria.fr/rapports/sophia/RR-5208.html
30 */
31#include <sys/param.h>
32#include <sys/kernel.h>
33#include <sys/module.h>
34#include <sys/socket.h>
35#include <sys/sysctl.h>
36
37#include <net/if.h>
38#include <net/if_media.h>
39
40#ifdef INET
41#include <netinet/in.h>
42#include <netinet/if_ether.h>
43#endif
44
45#include <net80211/ieee80211.h>
46#include <net80211/ieee80211_var.h>
47#include <net80211/ieee80211_amrr.h>
48
49#define is_success(amn)	\
50	((amn)->amn_retrycnt < (amn)->amn_txcnt / 10)
51#define is_failure(amn)	\
52	((amn)->amn_retrycnt > (amn)->amn_txcnt / 3)
53#define is_enough(amn)		\
54	((amn)->amn_txcnt > 10)
55#define is_min_rate(ni)		\
56	((ni)->ni_txrate == 0)
57#define is_max_rate(ni)		\
58	((ni)->ni_txrate == (ni)->ni_rates.rs_nrates - 1)
59#define increase_rate(ni)	\
60	((ni)->ni_txrate++)
61#define decrease_rate(ni)	\
62	((ni)->ni_txrate--)
63#define reset_cnt(amn)		\
64	do { (amn)->amn_txcnt = (amn)->amn_retrycnt = 0; } while (0)
65
66void
67ieee80211_amrr_init(struct ieee80211_amrr *amrr,
68    struct ieee80211com *ic, int min, int max)
69{
70	/* XXX bounds check? */
71	amrr->amrr_min_success_threshold = min;
72	amrr->amrr_max_success_threshold = max;
73	amrr->amrr_ic = ic;
74}
75
76void
77ieee80211_amrr_node_init(struct ieee80211_amrr *amrr,
78    struct ieee80211_amrr_node *amn)
79{
80	amn->amn_success = 0;
81	amn->amn_recovery = 0;
82	amn->amn_txcnt = amn->amn_retrycnt = 0;
83	amn->amn_success_threshold = amrr->amrr_min_success_threshold;
84}
85
86/*
87 * Update ni->ni_txrate.
88 */
89void
90ieee80211_amrr_choose(struct ieee80211_amrr *amrr, struct ieee80211_node *ni,
91    struct ieee80211_amrr_node *amn)
92{
93	int need_change = 0;
94
95	if (is_success(amn) && is_enough(amn)) {
96		amn->amn_success++;
97		if (amn->amn_success >= amn->amn_success_threshold &&
98		    !is_max_rate(ni)) {
99			amn->amn_recovery = 1;
100			amn->amn_success = 0;
101			increase_rate(ni);
102			IEEE80211_DPRINTF(amrr->amrr_ic, IEEE80211_MSG_RATECTL,
103			    "AMRR increasing rate %d (txcnt=%d "
104			    "retrycnt=%d)\n",
105			    ni->ni_rates.rs_rates[ni->ni_txrate] &
106				IEEE80211_RATE_VAL,
107			    amn->amn_txcnt, amn->amn_retrycnt);
108			need_change = 1;
109		} else {
110			amn->amn_recovery = 0;
111		}
112	} else if (is_failure(amn)) {
113		amn->amn_success = 0;
114		if (!is_min_rate(ni)) {
115			if (amn->amn_recovery) {
116				amn->amn_success_threshold *= 2;
117				if (amn->amn_success_threshold >
118				    amrr->amrr_max_success_threshold)
119					amn->amn_success_threshold =
120					    amrr->amrr_max_success_threshold;
121			} else {
122				amn->amn_success_threshold =
123				    amrr->amrr_min_success_threshold;
124			}
125			decrease_rate(ni);
126			IEEE80211_DPRINTF(amrr->amrr_ic, IEEE80211_MSG_RATECTL,
127			    "AMRR decreasing rate %d (txcnt=%d "
128			    "retrycnt=%d)\n",
129			    ni->ni_rates.rs_rates[ni->ni_txrate] &
130				IEEE80211_RATE_VAL,
131			    amn->amn_txcnt, amn->amn_retrycnt);
132			need_change = 1;
133		}
134		amn->amn_recovery = 0;
135	}
136
137	if (is_enough(amn) || need_change)
138		reset_cnt(amn);
139}
140
141/*
142 * Module glue.
143 */
144static int
145amrr_modevent(module_t mod, int type, void *unused)
146{
147	switch (type) {
148	case MOD_LOAD:
149		if (bootverbose)
150			printf("wlan_amrr: <AMRR Transmit Rate Control Algorithm>\n");
151		return 0;
152	case MOD_UNLOAD:
153		return 0;
154	}
155	return EINVAL;
156}
157
158static moduledata_t amrr_mod = {
159	"wlan_amrr",
160	amrr_modevent,
161	0
162};
163DECLARE_MODULE(wlan_amrr, amrr_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
164MODULE_VERSION(wlan_amrr, 1);
165