2 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 * Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
10 * Sponsored by Indranet Technologies Ltd
13 * Copyright (c) 2005 John Bicket
14 * All rights reserved.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer,
21 * without modification.
22 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
23 * similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
24 * redistribution must be conditioned upon including a substantially
25 * similar Disclaimer requirement for further binary redistribution.
26 * 3. Neither the names of the above-listed copyright holders nor the names
27 * of any contributors may be used to endorse or promote products derived
28 * from this software without specific prior written permission.
30 * Alternatively, this software may be distributed under the terms of the
31 * GNU General Public License ("GPL") version 2 as published by the Free
32 * Software Foundation.
35 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
38 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
39 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
40 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
41 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
42 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
43 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
44 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
45 * THE POSSIBILITY OF SUCH DAMAGES.
47 #include <linux/netdevice.h>
48 #include <linux/types.h>
49 #include <linux/skbuff.h>
50 #include <linux/debugfs.h>
51 #include <linux/random.h>
52 #include <linux/ieee80211.h>
53 #include <net/mac80211.h>
55 #include "rc80211_minstrel.h"
57 #define SAMPLE_COLUMNS 10
58 #define SAMPLE_TBL(_mi, _idx, _col) \
59 _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
61 /* convert mac80211 rate index to local array index */
63 rix_to_ndx(struct minstrel_sta_info
*mi
, int rix
)
66 for (i
= rix
; i
>= 0; i
--)
67 if (mi
->r
[i
].rix
== rix
)
69 WARN_ON(mi
->r
[i
].rix
!= rix
);
74 use_low_rate(struct sk_buff
*skb
)
76 struct ieee80211_hdr
*hdr
= (struct ieee80211_hdr
*) skb
->data
;
77 struct ieee80211_tx_info
*info
= IEEE80211_SKB_CB(skb
);
80 fc
= le16_to_cpu(hdr
->frame_control
);
82 return ((info
->flags
& IEEE80211_TX_CTL_NO_ACK
) ||
83 (fc
& IEEE80211_FCTL_FTYPE
) != IEEE80211_FTYPE_DATA
||
84 is_multicast_ether_addr(hdr
->addr1
));
89 minstrel_update_stats(struct minstrel_priv
*mp
, struct minstrel_sta_info
*mi
)
91 u32 max_tp
= 0, index_max_tp
= 0, index_max_tp2
= 0;
92 u32 max_prob
= 0, index_max_prob
= 0;
97 mi
->stats_update
= jiffies
;
98 for (i
= 0; i
< mi
->n_rates
; i
++) {
99 struct minstrel_rate
*mr
= &mi
->r
[i
];
101 usecs
= mr
->perfect_tx_time
;
105 /* To avoid rounding issues, probabilities scale from 0 (0%)
108 p
= (mr
->success
* 18000) / mr
->attempts
;
109 mr
->succ_hist
+= mr
->success
;
110 mr
->att_hist
+= mr
->attempts
;
112 p
= ((p
* (100 - mp
->ewma_level
)) + (mr
->probability
*
113 mp
->ewma_level
)) / 100;
115 mr
->cur_tp
= p
* (1000000 / usecs
);
118 mr
->last_success
= mr
->success
;
119 mr
->last_attempts
= mr
->attempts
;
123 /* Sample less often below the 10% chance of success.
124 * Sample less often above the 95% chance of success. */
125 if ((mr
->probability
> 17100) || (mr
->probability
< 1800)) {
126 mr
->adjusted_retry_count
= mr
->retry_count
>> 1;
127 if (mr
->adjusted_retry_count
> 2)
128 mr
->adjusted_retry_count
= 2;
130 mr
->adjusted_retry_count
= mr
->retry_count
;
132 if (!mr
->adjusted_retry_count
)
133 mr
->adjusted_retry_count
= 2;
136 for (i
= 0; i
< mi
->n_rates
; i
++) {
137 struct minstrel_rate
*mr
= &mi
->r
[i
];
138 if (max_tp
< mr
->cur_tp
) {
142 if (max_prob
< mr
->probability
) {
144 max_prob
= mr
->probability
;
149 for (i
= 0; i
< mi
->n_rates
; i
++) {
150 struct minstrel_rate
*mr
= &mi
->r
[i
];
152 if (i
== index_max_tp
)
155 if (max_tp
< mr
->cur_tp
) {
160 mi
->max_tp_rate
= index_max_tp
;
161 mi
->max_tp_rate2
= index_max_tp2
;
162 mi
->max_prob_rate
= index_max_prob
;
166 minstrel_tx_status(void *priv
, struct ieee80211_supported_band
*sband
,
167 struct ieee80211_sta
*sta
, void *priv_sta
,
170 struct minstrel_sta_info
*mi
= priv_sta
;
171 struct ieee80211_tx_info
*info
= IEEE80211_SKB_CB(skb
);
172 struct ieee80211_tx_rate
*ar
= info
->status
.rates
;
176 success
= !!(info
->flags
& IEEE80211_TX_STAT_ACK
);
178 for (i
= 0; i
< IEEE80211_TX_MAX_RATES
; i
++) {
182 ndx
= rix_to_ndx(mi
, ar
[i
].idx
);
183 mi
->r
[ndx
].attempts
+= ar
[i
].count
;
185 if ((i
!= IEEE80211_TX_MAX_RATES
- 1) && (ar
[i
+ 1].idx
< 0))
186 mi
->r
[ndx
].success
+= success
;
189 if ((info
->flags
& IEEE80211_TX_CTL_RATE_CTRL_PROBE
) && (i
>= 0))
192 if (mi
->sample_deferred
> 0)
193 mi
->sample_deferred
--;
197 static inline unsigned int
198 minstrel_get_retry_count(struct minstrel_rate
*mr
,
199 struct ieee80211_tx_info
*info
)
201 unsigned int retry
= mr
->adjusted_retry_count
;
203 if (info
->control
.rates
[0].flags
& IEEE80211_TX_RC_USE_RTS_CTS
)
204 retry
= max(2U, min(mr
->retry_count_rtscts
, retry
));
205 else if (info
->control
.rates
[0].flags
& IEEE80211_TX_RC_USE_CTS_PROTECT
)
206 retry
= max(2U, min(mr
->retry_count_cts
, retry
));
212 minstrel_get_next_sample(struct minstrel_sta_info
*mi
)
214 unsigned int sample_ndx
;
215 sample_ndx
= SAMPLE_TBL(mi
, mi
->sample_idx
, mi
->sample_column
);
217 if (mi
->sample_idx
> (mi
->n_rates
- 2)) {
220 if (mi
->sample_column
>= SAMPLE_COLUMNS
)
221 mi
->sample_column
= 0;
227 minstrel_get_rate(void *priv
, struct ieee80211_sta
*sta
,
228 void *priv_sta
, struct ieee80211_tx_rate_control
*txrc
)
230 struct sk_buff
*skb
= txrc
->skb
;
231 struct ieee80211_supported_band
*sband
= txrc
->sband
;
232 struct ieee80211_tx_info
*info
= IEEE80211_SKB_CB(skb
);
233 struct minstrel_sta_info
*mi
= priv_sta
;
234 struct minstrel_priv
*mp
= priv
;
235 struct ieee80211_tx_rate
*ar
= info
->control
.rates
;
236 unsigned int ndx
, sample_ndx
= 0;
238 bool sample_slower
= false;
244 if (!sta
|| !mi
|| use_low_rate(skb
)) {
245 ar
[0].idx
= rate_lowest_index(sband
, sta
);
246 ar
[0].count
= mp
->max_retry
;
250 mrr
= mp
->has_mrr
&& !txrc
->rts
&& !txrc
->bss_conf
->use_cts_prot
;
252 if (time_after(jiffies
, mi
->stats_update
+ (mp
->update_interval
*
254 minstrel_update_stats(mp
, mi
);
256 ndx
= mi
->max_tp_rate
;
259 sample_rate
= mp
->lookaround_rate_mrr
;
261 sample_rate
= mp
->lookaround_rate
;
264 delta
= (mi
->packet_count
* sample_rate
/ 100) -
265 (mi
->sample_count
+ mi
->sample_deferred
/ 2);
267 /* delta > 0: sampling required */
269 if (mi
->packet_count
>= 10000) {
270 mi
->sample_deferred
= 0;
271 mi
->sample_count
= 0;
272 mi
->packet_count
= 0;
273 } else if (delta
> mi
->n_rates
* 2) {
274 /* With multi-rate retry, not every planned sample
275 * attempt actually gets used, due to the way the retry
276 * chain is set up - [max_tp,sample,prob,lowest] for
277 * sample_rate < max_tp.
279 * If there's too much sampling backlog and the link
280 * starts getting worse, minstrel would start bursting
281 * out lots of sampling frames, which would result
282 * in a large throughput loss. */
283 mi
->sample_count
+= (delta
- mi
->n_rates
* 2);
286 sample_ndx
= minstrel_get_next_sample(mi
);
288 sample_slower
= mrr
&& (mi
->r
[sample_ndx
].perfect_tx_time
>
289 mi
->r
[ndx
].perfect_tx_time
);
291 if (!sample_slower
) {
295 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
296 * packets that have the sampling rate deferred to the
297 * second MRR stage. Increase the sample counter only
298 * if the deferred sample rate was actually used.
299 * Use the sample_deferred counter to make sure that
300 * the sampling is not done in large bursts */
301 info
->flags
|= IEEE80211_TX_CTL_RATE_CTRL_PROBE
;
302 mi
->sample_deferred
++;
305 ar
[0].idx
= mi
->r
[ndx
].rix
;
306 ar
[0].count
= minstrel_get_retry_count(&mi
->r
[ndx
], info
);
309 ar
[1].idx
= mi
->lowest_rix
;
310 ar
[1].count
= mp
->max_retry
;
317 mrr_ndx
[0] = sample_ndx
;
319 mrr_ndx
[0] = mi
->max_tp_rate
;
321 mrr_ndx
[0] = mi
->max_tp_rate2
;
323 mrr_ndx
[1] = mi
->max_prob_rate
;
325 for (i
= 1; i
< 4; i
++) {
326 ar
[i
].idx
= mi
->r
[mrr_ndx
[i
- 1]].rix
;
327 ar
[i
].count
= mi
->r
[mrr_ndx
[i
- 1]].adjusted_retry_count
;
333 calc_rate_durations(struct minstrel_sta_info
*mi
, struct ieee80211_local
*local
,
334 struct minstrel_rate
*d
, struct ieee80211_rate
*rate
)
336 int erp
= !!(rate
->flags
& IEEE80211_RATE_ERP_G
);
338 d
->perfect_tx_time
= ieee80211_frame_duration(local
, 1200,
339 rate
->bitrate
, erp
, 1);
340 d
->ack_time
= ieee80211_frame_duration(local
, 10,
341 rate
->bitrate
, erp
, 1);
345 init_sample_table(struct minstrel_sta_info
*mi
)
347 unsigned int i
, col
, new_idx
;
348 unsigned int n_srates
= mi
->n_rates
- 1;
351 mi
->sample_column
= 0;
353 memset(mi
->sample_table
, 0, SAMPLE_COLUMNS
* mi
->n_rates
);
355 for (col
= 0; col
< SAMPLE_COLUMNS
; col
++) {
356 for (i
= 0; i
< n_srates
; i
++) {
357 get_random_bytes(rnd
, sizeof(rnd
));
358 new_idx
= (i
+ rnd
[i
& 7]) % n_srates
;
360 while (SAMPLE_TBL(mi
, new_idx
, col
) != 0)
361 new_idx
= (new_idx
+ 1) % n_srates
;
363 /* Don't sample the slowest rate (i.e. slowest base
364 * rate). We must presume that the slowest rate works
365 * fine, or else other management frames will also be
366 * failing and the link will break */
367 SAMPLE_TBL(mi
, new_idx
, col
) = i
+ 1;
373 minstrel_rate_init(void *priv
, struct ieee80211_supported_band
*sband
,
374 struct ieee80211_sta
*sta
, void *priv_sta
)
376 struct minstrel_sta_info
*mi
= priv_sta
;
377 struct minstrel_priv
*mp
= priv
;
378 struct minstrel_rate
*mr_ctl
;
379 unsigned int i
, n
= 0;
380 unsigned int t_slot
= 9; /* FIXME: get real slot time */
382 mi
->lowest_rix
= rate_lowest_index(sband
, sta
);
383 mr_ctl
= &mi
->r
[rix_to_ndx(mi
, mi
->lowest_rix
)];
384 mi
->sp_ack_dur
= mr_ctl
->ack_time
;
386 for (i
= 0; i
< sband
->n_bitrates
; i
++) {
387 struct minstrel_rate
*mr
= &mi
->r
[n
];
388 unsigned int tx_time
= 0, tx_time_cts
= 0, tx_time_rtscts
= 0;
389 unsigned int tx_time_single
;
390 unsigned int cw
= mp
->cw_min
;
392 if (!rate_supported(sta
, sband
->band
, i
))
395 memset(mr
, 0, sizeof(*mr
));
398 mr
->bitrate
= sband
->bitrates
[i
].bitrate
/ 5;
399 calc_rate_durations(mi
, hw_to_local(mp
->hw
), mr
,
400 &sband
->bitrates
[i
]);
402 /* calculate maximum number of retransmissions before
403 * fallback (based on maximum segment size) */
405 mr
->retry_count_cts
= 1;
406 mr
->retry_count_rtscts
= 1;
407 tx_time
= mr
->perfect_tx_time
+ mi
->sp_ack_dur
;
409 /* add one retransmission */
410 tx_time_single
= mr
->ack_time
+ mr
->perfect_tx_time
;
412 /* contention window */
413 tx_time_single
+= t_slot
+ min(cw
, mp
->cw_max
);
416 tx_time
+= tx_time_single
;
417 tx_time_cts
+= tx_time_single
+ mi
->sp_ack_dur
;
418 tx_time_rtscts
+= tx_time_single
+ 2 * mi
->sp_ack_dur
;
419 if ((tx_time_cts
< mp
->segment_size
) &&
420 (mr
->retry_count_cts
< mp
->max_retry
))
421 mr
->retry_count_cts
++;
422 if ((tx_time_rtscts
< mp
->segment_size
) &&
423 (mr
->retry_count_rtscts
< mp
->max_retry
))
424 mr
->retry_count_rtscts
++;
425 } while ((tx_time
< mp
->segment_size
) &&
426 (++mr
->retry_count
< mp
->max_retry
));
427 mr
->adjusted_retry_count
= mr
->retry_count
;
430 for (i
= n
; i
< sband
->n_bitrates
; i
++) {
431 struct minstrel_rate
*mr
= &mi
->r
[i
];
436 mi
->stats_update
= jiffies
;
438 init_sample_table(mi
);
442 minstrel_alloc_sta(void *priv
, struct ieee80211_sta
*sta
, gfp_t gfp
)
444 struct ieee80211_supported_band
*sband
;
445 struct minstrel_sta_info
*mi
;
446 struct minstrel_priv
*mp
= priv
;
447 struct ieee80211_hw
*hw
= mp
->hw
;
451 mi
= kzalloc(sizeof(struct minstrel_sta_info
), gfp
);
455 for (i
= 0; i
< IEEE80211_NUM_BANDS
; i
++) {
456 sband
= hw
->wiphy
->bands
[hw
->conf
.channel
->band
];
457 if (sband
->n_bitrates
> max_rates
)
458 max_rates
= sband
->n_bitrates
;
461 mi
->r
= kzalloc(sizeof(struct minstrel_rate
) * max_rates
, gfp
);
465 mi
->sample_table
= kmalloc(SAMPLE_COLUMNS
* max_rates
, gfp
);
466 if (!mi
->sample_table
)
469 mi
->stats_update
= jiffies
;
480 minstrel_free_sta(void *priv
, struct ieee80211_sta
*sta
, void *priv_sta
)
482 struct minstrel_sta_info
*mi
= priv_sta
;
484 kfree(mi
->sample_table
);
490 minstrel_clear(void *priv
)
495 minstrel_alloc(struct ieee80211_hw
*hw
, struct dentry
*debugfsdir
)
497 struct minstrel_priv
*mp
;
499 mp
= kzalloc(sizeof(struct minstrel_priv
), GFP_ATOMIC
);
503 /* contention window settings
504 * Just an approximation. Using the per-queue values would complicate
505 * the calculations and is probably unnecessary */
509 /* number of packets (in %) to use for sampling other rates
510 * sample less often for non-mrr packets, because the overhead
511 * is much higher than with mrr */
512 mp
->lookaround_rate
= 5;
513 mp
->lookaround_rate_mrr
= 10;
515 /* moving average weight for EWMA */
518 /* maximum time that the hw is allowed to stay in one MRR segment */
519 mp
->segment_size
= 6000;
521 if (hw
->max_rate_tries
> 0)
522 mp
->max_retry
= hw
->max_rate_tries
;
524 /* safe default, does not necessarily have to match hw properties */
527 if (hw
->max_rates
>= 4)
531 mp
->update_interval
= 100;
537 minstrel_free(void *priv
)
542 static struct rate_control_ops mac80211_minstrel
= {
544 .tx_status
= minstrel_tx_status
,
545 .get_rate
= minstrel_get_rate
,
546 .rate_init
= minstrel_rate_init
,
547 .clear
= minstrel_clear
,
548 .alloc
= minstrel_alloc
,
549 .free
= minstrel_free
,
550 .alloc_sta
= minstrel_alloc_sta
,
551 .free_sta
= minstrel_free_sta
,
552 #ifdef CONFIG_MAC80211_DEBUGFS
553 .add_sta_debugfs
= minstrel_add_sta_debugfs
,
554 .remove_sta_debugfs
= minstrel_remove_sta_debugfs
,
559 rc80211_minstrel_init(void)
561 return ieee80211_rate_control_register(&mac80211_minstrel
);
565 rc80211_minstrel_exit(void)
567 ieee80211_rate_control_unregister(&mac80211_minstrel
);