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minstrel_ht: increase sampling frequency
[deliverable/linux.git] / net / mac80211 / rc80211_minstrel_ht.c
1 /*
2 * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
3 *
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.
7 */
8 #include <linux/netdevice.h>
9 #include <linux/types.h>
10 #include <linux/skbuff.h>
11 #include <linux/debugfs.h>
12 #include <linux/random.h>
13 #include <linux/ieee80211.h>
14 #include <net/mac80211.h>
15 #include "rate.h"
16 #include "rc80211_minstrel.h"
17 #include "rc80211_minstrel_ht.h"
18
19 #define AVG_PKT_SIZE 1200
20 #define SAMPLE_COLUMNS 10
21 #define EWMA_LEVEL 75
22
23 /* Number of bits for an average sized packet */
24 #define MCS_NBITS (AVG_PKT_SIZE << 3)
25
26 /* Number of symbols for a packet with (bps) bits per symbol */
27 #define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
28
29 /* Transmission time (nanoseconds) for a packet containing (syms) symbols */
30 #define MCS_SYMBOL_TIME(sgi, syms) \
31 (sgi ? \
32 ((syms) * 18000 + 4000) / 5 : /* syms * 3.6 us */ \
33 ((syms) * 1000) << 2 /* syms * 4 us */ \
34 )
35
36 /* Transmit duration for the raw data part of an average sized packet */
37 #define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
38
39 /*
40 * Define group sort order: HT40 -> SGI -> #streams
41 */
42 #define GROUP_IDX(_streams, _sgi, _ht40) \
43 MINSTREL_MAX_STREAMS * 2 * _ht40 + \
44 MINSTREL_MAX_STREAMS * _sgi + \
45 _streams - 1
46
47 /* MCS rate information for an MCS group */
48 #define MCS_GROUP(_streams, _sgi, _ht40) \
49 [GROUP_IDX(_streams, _sgi, _ht40)] = { \
50 .streams = _streams, \
51 .flags = \
52 (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
53 (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
54 .duration = { \
55 MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \
56 MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \
57 MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \
58 MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \
59 MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \
60 MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \
61 MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \
62 MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \
63 } \
64 }
65
66 #define CCK_DURATION(_bitrate, _short, _len) \
67 (1000 * (10 /* SIFS */ + \
68 (_short ? 72 + 24 : 144 + 48 ) + \
69 (8 * (_len + 4) * 10) / (_bitrate)))
70
71 #define CCK_ACK_DURATION(_bitrate, _short) \
72 (CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \
73 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))
74
75 #define CCK_DURATION_LIST(_short) \
76 CCK_ACK_DURATION(10, _short), \
77 CCK_ACK_DURATION(20, _short), \
78 CCK_ACK_DURATION(55, _short), \
79 CCK_ACK_DURATION(110, _short)
80
81 #define CCK_GROUP \
82 [MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = { \
83 .streams = 0, \
84 .duration = { \
85 CCK_DURATION_LIST(false), \
86 CCK_DURATION_LIST(true) \
87 } \
88 }
89
90 /*
91 * To enable sufficiently targeted rate sampling, MCS rates are divided into
92 * groups, based on the number of streams and flags (HT40, SGI) that they
93 * use.
94 *
95 * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
96 * HT40 -> SGI -> #streams
97 */
98 const struct mcs_group minstrel_mcs_groups[] = {
99 MCS_GROUP(1, 0, 0),
100 MCS_GROUP(2, 0, 0),
101 #if MINSTREL_MAX_STREAMS >= 3
102 MCS_GROUP(3, 0, 0),
103 #endif
104
105 MCS_GROUP(1, 1, 0),
106 MCS_GROUP(2, 1, 0),
107 #if MINSTREL_MAX_STREAMS >= 3
108 MCS_GROUP(3, 1, 0),
109 #endif
110
111 MCS_GROUP(1, 0, 1),
112 MCS_GROUP(2, 0, 1),
113 #if MINSTREL_MAX_STREAMS >= 3
114 MCS_GROUP(3, 0, 1),
115 #endif
116
117 MCS_GROUP(1, 1, 1),
118 MCS_GROUP(2, 1, 1),
119 #if MINSTREL_MAX_STREAMS >= 3
120 MCS_GROUP(3, 1, 1),
121 #endif
122
123 /* must be last */
124 CCK_GROUP
125 };
126
127 #define MINSTREL_CCK_GROUP (ARRAY_SIZE(minstrel_mcs_groups) - 1)
128
129 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
130
131 /*
132 * Perform EWMA (Exponentially Weighted Moving Average) calculation
133 */
134 static int
135 minstrel_ewma(int old, int new, int weight)
136 {
137 return (new * (100 - weight) + old * weight) / 100;
138 }
139
140 /*
141 * Look up an MCS group index based on mac80211 rate information
142 */
143 static int
144 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
145 {
146 return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
147 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
148 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
149 }
150
151 static struct minstrel_rate_stats *
152 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
153 struct ieee80211_tx_rate *rate)
154 {
155 int group, idx;
156
157 if (rate->flags & IEEE80211_TX_RC_MCS) {
158 group = minstrel_ht_get_group_idx(rate);
159 idx = rate->idx % MCS_GROUP_RATES;
160 } else {
161 group = MINSTREL_CCK_GROUP;
162
163 for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
164 if (rate->idx == mp->cck_rates[idx])
165 break;
166
167 /* short preamble */
168 if (!(mi->groups[group].supported & BIT(idx)))
169 idx += 4;
170 }
171 return &mi->groups[group].rates[idx];
172 }
173
174 static inline struct minstrel_rate_stats *
175 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
176 {
177 return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
178 }
179
180
181 /*
182 * Recalculate success probabilities and counters for a rate using EWMA
183 */
184 static void
185 minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
186 {
187 if (unlikely(mr->attempts > 0)) {
188 mr->sample_skipped = 0;
189 mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
190 if (!mr->att_hist)
191 mr->probability = mr->cur_prob;
192 else
193 mr->probability = minstrel_ewma(mr->probability,
194 mr->cur_prob, EWMA_LEVEL);
195 mr->att_hist += mr->attempts;
196 mr->succ_hist += mr->success;
197 } else {
198 mr->sample_skipped++;
199 }
200 mr->last_success = mr->success;
201 mr->last_attempts = mr->attempts;
202 mr->success = 0;
203 mr->attempts = 0;
204 }
205
206 /*
207 * Calculate throughput based on the average A-MPDU length, taking into account
208 * the expected number of retransmissions and their expected length
209 */
210 static void
211 minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
212 {
213 struct minstrel_rate_stats *mr;
214 unsigned int nsecs = 0;
215 unsigned int tp;
216
217 mr = &mi->groups[group].rates[rate];
218
219 if (mr->probability < MINSTREL_FRAC(1, 10)) {
220 mr->cur_tp = 0;
221 return;
222 }
223
224 if (group != MINSTREL_CCK_GROUP)
225 nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
226
227 nsecs += minstrel_mcs_groups[group].duration[rate];
228 tp = 1000000 * ((mr->probability * 1000) / nsecs);
229
230 mr->cur_tp = MINSTREL_TRUNC(tp);
231 }
232
233 /*
234 * Update rate statistics and select new primary rates
235 *
236 * Rules for rate selection:
237 * - max_prob_rate must use only one stream, as a tradeoff between delivery
238 * probability and throughput during strong fluctuations
239 * - as long as the max prob rate has a probability of more than 3/4, pick
240 * higher throughput rates, even if the probablity is a bit lower
241 */
242 static void
243 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
244 {
245 struct minstrel_mcs_group_data *mg;
246 struct minstrel_rate_stats *mr;
247 int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
248 int group, i, index;
249 int prob_max_streams = 1;
250
251 if (mi->ampdu_packets > 0) {
252 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
253 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
254 mi->ampdu_len = 0;
255 mi->ampdu_packets = 0;
256 }
257
258 mi->sample_slow = 0;
259 mi->sample_count = 0;
260 mi->max_tp_rate = 0;
261 mi->max_tp_rate2 = 0;
262 mi->max_prob_rate = 0;
263
264 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
265 cur_prob = 0;
266 cur_prob_tp = 0;
267 cur_tp = 0;
268 cur_tp2 = 0;
269
270 mg = &mi->groups[group];
271 if (!mg->supported)
272 continue;
273
274 mg->max_tp_rate = 0;
275 mg->max_tp_rate2 = 0;
276 mg->max_prob_rate = 0;
277 mi->sample_count++;
278
279 for (i = 0; i < MCS_GROUP_RATES; i++) {
280 if (!(mg->supported & BIT(i)))
281 continue;
282
283 mr = &mg->rates[i];
284 mr->retry_updated = false;
285 index = MCS_GROUP_RATES * group + i;
286 minstrel_calc_rate_ewma(mr);
287 minstrel_ht_calc_tp(mi, group, i);
288
289 if (!mr->cur_tp)
290 continue;
291
292 if ((mr->cur_tp > cur_prob_tp && mr->probability >
293 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
294 mg->max_prob_rate = index;
295 cur_prob = mr->probability;
296 cur_prob_tp = mr->cur_tp;
297 }
298
299 if (mr->cur_tp > cur_tp) {
300 swap(index, mg->max_tp_rate);
301 cur_tp = mr->cur_tp;
302 mr = minstrel_get_ratestats(mi, index);
303 }
304
305 if (index >= mg->max_tp_rate)
306 continue;
307
308 if (mr->cur_tp > cur_tp2) {
309 mg->max_tp_rate2 = index;
310 cur_tp2 = mr->cur_tp;
311 }
312 }
313 }
314
315 /* try to sample all available rates during each interval */
316 mi->sample_count *= 8;
317
318 cur_prob = 0;
319 cur_prob_tp = 0;
320 cur_tp = 0;
321 cur_tp2 = 0;
322 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
323 mg = &mi->groups[group];
324 if (!mg->supported)
325 continue;
326
327 mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
328 if (cur_tp < mr->cur_tp) {
329 mi->max_tp_rate2 = mi->max_tp_rate;
330 cur_tp2 = cur_tp;
331 mi->max_tp_rate = mg->max_tp_rate;
332 cur_tp = mr->cur_tp;
333 prob_max_streams = minstrel_mcs_groups[group].streams - 1;
334 }
335
336 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
337 if (cur_tp2 < mr->cur_tp) {
338 mi->max_tp_rate2 = mg->max_tp_rate2;
339 cur_tp2 = mr->cur_tp;
340 }
341 }
342
343 if (prob_max_streams < 1)
344 prob_max_streams = 1;
345
346 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
347 mg = &mi->groups[group];
348 if (!mg->supported)
349 continue;
350 mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
351 if (cur_prob_tp < mr->cur_tp &&
352 minstrel_mcs_groups[group].streams <= prob_max_streams) {
353 mi->max_prob_rate = mg->max_prob_rate;
354 cur_prob = mr->cur_prob;
355 cur_prob_tp = mr->cur_tp;
356 }
357 }
358
359
360 mi->stats_update = jiffies;
361 }
362
363 static bool
364 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
365 {
366 if (rate->idx < 0)
367 return false;
368
369 if (!rate->count)
370 return false;
371
372 if (rate->flags & IEEE80211_TX_RC_MCS)
373 return true;
374
375 return rate->idx == mp->cck_rates[0] ||
376 rate->idx == mp->cck_rates[1] ||
377 rate->idx == mp->cck_rates[2] ||
378 rate->idx == mp->cck_rates[3];
379 }
380
381 static void
382 minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
383 {
384 struct minstrel_mcs_group_data *mg;
385
386 for (;;) {
387 mi->sample_group++;
388 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
389 mg = &mi->groups[mi->sample_group];
390
391 if (!mg->supported)
392 continue;
393
394 if (++mg->index >= MCS_GROUP_RATES) {
395 mg->index = 0;
396 if (++mg->column >= ARRAY_SIZE(sample_table))
397 mg->column = 0;
398 }
399 break;
400 }
401 }
402
403 static void
404 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
405 bool primary)
406 {
407 int group, orig_group;
408
409 orig_group = group = *idx / MCS_GROUP_RATES;
410 while (group > 0) {
411 group--;
412
413 if (!mi->groups[group].supported)
414 continue;
415
416 if (minstrel_mcs_groups[group].streams >
417 minstrel_mcs_groups[orig_group].streams)
418 continue;
419
420 if (primary)
421 *idx = mi->groups[group].max_tp_rate;
422 else
423 *idx = mi->groups[group].max_tp_rate2;
424 break;
425 }
426 }
427
428 static void
429 minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
430 {
431 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
432 struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
433 u16 tid;
434
435 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
436 return;
437
438 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
439 return;
440
441 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
442 if (likely(sta->ampdu_mlme.tid_tx[tid]))
443 return;
444
445 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
446 return;
447
448 ieee80211_start_tx_ba_session(pubsta, tid, 5000);
449 }
450
451 static void
452 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
453 struct ieee80211_sta *sta, void *priv_sta,
454 struct sk_buff *skb)
455 {
456 struct minstrel_ht_sta_priv *msp = priv_sta;
457 struct minstrel_ht_sta *mi = &msp->ht;
458 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
459 struct ieee80211_tx_rate *ar = info->status.rates;
460 struct minstrel_rate_stats *rate, *rate2;
461 struct minstrel_priv *mp = priv;
462 bool last;
463 int i;
464
465 if (!msp->is_ht)
466 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
467
468 /* This packet was aggregated but doesn't carry status info */
469 if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
470 !(info->flags & IEEE80211_TX_STAT_AMPDU))
471 return;
472
473 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
474 info->status.ampdu_ack_len =
475 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
476 info->status.ampdu_len = 1;
477 }
478
479 mi->ampdu_packets++;
480 mi->ampdu_len += info->status.ampdu_len;
481
482 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
483 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
484 mi->sample_tries = 2;
485 mi->sample_count--;
486 }
487
488 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
489 mi->sample_packets += info->status.ampdu_len;
490
491 last = !minstrel_ht_txstat_valid(mp, &ar[0]);
492 for (i = 0; !last; i++) {
493 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
494 !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
495
496 rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
497
498 if (last)
499 rate->success += info->status.ampdu_ack_len;
500
501 rate->attempts += ar[i].count * info->status.ampdu_len;
502 }
503
504 /*
505 * check for sudden death of spatial multiplexing,
506 * downgrade to a lower number of streams if necessary.
507 */
508 rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
509 if (rate->attempts > 30 &&
510 MINSTREL_FRAC(rate->success, rate->attempts) <
511 MINSTREL_FRAC(20, 100))
512 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
513
514 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
515 if (rate2->attempts > 30 &&
516 MINSTREL_FRAC(rate2->success, rate2->attempts) <
517 MINSTREL_FRAC(20, 100))
518 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
519
520 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
521 minstrel_ht_update_stats(mp, mi);
522 if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
523 mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
524 minstrel_aggr_check(sta, skb);
525 }
526 }
527
528 static void
529 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
530 int index)
531 {
532 struct minstrel_rate_stats *mr;
533 const struct mcs_group *group;
534 unsigned int tx_time, tx_time_rtscts, tx_time_data;
535 unsigned int cw = mp->cw_min;
536 unsigned int ctime = 0;
537 unsigned int t_slot = 9; /* FIXME */
538 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
539 unsigned int overhead = 0, overhead_rtscts = 0;
540
541 mr = minstrel_get_ratestats(mi, index);
542 if (mr->probability < MINSTREL_FRAC(1, 10)) {
543 mr->retry_count = 1;
544 mr->retry_count_rtscts = 1;
545 return;
546 }
547
548 mr->retry_count = 2;
549 mr->retry_count_rtscts = 2;
550 mr->retry_updated = true;
551
552 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
553 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
554
555 /* Contention time for first 2 tries */
556 ctime = (t_slot * cw) >> 1;
557 cw = min((cw << 1) | 1, mp->cw_max);
558 ctime += (t_slot * cw) >> 1;
559 cw = min((cw << 1) | 1, mp->cw_max);
560
561 if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
562 overhead = mi->overhead;
563 overhead_rtscts = mi->overhead_rtscts;
564 }
565
566 /* Total TX time for data and Contention after first 2 tries */
567 tx_time = ctime + 2 * (overhead + tx_time_data);
568 tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
569
570 /* See how many more tries we can fit inside segment size */
571 do {
572 /* Contention time for this try */
573 ctime = (t_slot * cw) >> 1;
574 cw = min((cw << 1) | 1, mp->cw_max);
575
576 /* Total TX time after this try */
577 tx_time += ctime + overhead + tx_time_data;
578 tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
579
580 if (tx_time_rtscts < mp->segment_size)
581 mr->retry_count_rtscts++;
582 } while ((tx_time < mp->segment_size) &&
583 (++mr->retry_count < mp->max_retry));
584 }
585
586
587 static void
588 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
589 struct ieee80211_tx_rate *rate, int index,
590 bool sample, bool rtscts)
591 {
592 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
593 struct minstrel_rate_stats *mr;
594
595 mr = minstrel_get_ratestats(mi, index);
596 if (!mr->retry_updated)
597 minstrel_calc_retransmit(mp, mi, index);
598
599 if (sample)
600 rate->count = 1;
601 else if (mr->probability < MINSTREL_FRAC(20, 100))
602 rate->count = 2;
603 else if (rtscts)
604 rate->count = mr->retry_count_rtscts;
605 else
606 rate->count = mr->retry_count;
607
608 rate->flags = 0;
609 if (rtscts)
610 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
611
612 if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
613 rate->idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
614 return;
615 }
616
617 rate->flags |= IEEE80211_TX_RC_MCS | group->flags;
618 rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
619 }
620
621 static inline int
622 minstrel_get_duration(int index)
623 {
624 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
625 return group->duration[index % MCS_GROUP_RATES];
626 }
627
628 static int
629 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
630 {
631 struct minstrel_rate_stats *mr;
632 struct minstrel_mcs_group_data *mg;
633 int sample_idx = 0;
634
635 if (mi->sample_wait > 0) {
636 mi->sample_wait--;
637 return -1;
638 }
639
640 if (!mi->sample_tries)
641 return -1;
642
643 mi->sample_tries--;
644 mg = &mi->groups[mi->sample_group];
645 sample_idx = sample_table[mg->column][mg->index];
646 mr = &mg->rates[sample_idx];
647 sample_idx += mi->sample_group * MCS_GROUP_RATES;
648 minstrel_next_sample_idx(mi);
649
650 /*
651 * Sampling might add some overhead (RTS, no aggregation)
652 * to the frame. Hence, don't use sampling for the currently
653 * used max TP rate.
654 */
655 if (sample_idx == mi->max_tp_rate)
656 return -1;
657 /*
658 * When not using MRR, do not sample if the probability is already
659 * higher than 95% to avoid wasting airtime
660 */
661 if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
662 return -1;
663
664 /*
665 * Make sure that lower rates get sampled only occasionally,
666 * if the link is working perfectly.
667 */
668 if (minstrel_get_duration(sample_idx) >
669 minstrel_get_duration(mi->max_tp_rate)) {
670 if (mr->sample_skipped < 20)
671 return -1;
672
673 if (mi->sample_slow++ > 2)
674 return -1;
675 }
676
677 return sample_idx;
678 }
679
680 static void
681 minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
682 struct minstrel_ht_sta *mi, bool val)
683 {
684 u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
685
686 if (!supported || !mi->cck_supported_short)
687 return;
688
689 if (supported & (mi->cck_supported_short << (val * 4)))
690 return;
691
692 supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
693 mi->groups[MINSTREL_CCK_GROUP].supported = supported;
694 }
695
696 static void
697 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
698 struct ieee80211_tx_rate_control *txrc)
699 {
700 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
701 struct ieee80211_tx_rate *ar = info->status.rates;
702 struct minstrel_ht_sta_priv *msp = priv_sta;
703 struct minstrel_ht_sta *mi = &msp->ht;
704 struct minstrel_priv *mp = priv;
705 int sample_idx;
706 bool sample = false;
707
708 if (rate_control_send_low(sta, priv_sta, txrc))
709 return;
710
711 if (!msp->is_ht)
712 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
713
714 info->flags |= mi->tx_flags;
715 minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
716
717 /* Don't use EAPOL frames for sampling on non-mrr hw */
718 if (mp->hw->max_rates == 1 &&
719 txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
720 sample_idx = -1;
721 else
722 sample_idx = minstrel_get_sample_rate(mp, mi);
723
724 #ifdef CONFIG_MAC80211_DEBUGFS
725 /* use fixed index if set */
726 if (mp->fixed_rate_idx != -1) {
727 mi->max_tp_rate = mp->fixed_rate_idx;
728 mi->max_tp_rate2 = mp->fixed_rate_idx;
729 mi->max_prob_rate = mp->fixed_rate_idx;
730 sample_idx = -1;
731 }
732 #endif
733
734 if (sample_idx >= 0) {
735 sample = true;
736 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
737 true, false);
738 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
739 } else {
740 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
741 false, false);
742 }
743
744 if (mp->hw->max_rates >= 3) {
745 /*
746 * At least 3 tx rates supported, use
747 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
748 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
749 */
750 if (sample_idx >= 0)
751 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
752 false, false);
753 else
754 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
755 false, true);
756
757 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
758 false, !sample);
759
760 ar[3].count = 0;
761 ar[3].idx = -1;
762 } else if (mp->hw->max_rates == 2) {
763 /*
764 * Only 2 tx rates supported, use
765 * sample_rate -> max_prob_rate for sampling and
766 * max_tp_rate -> max_prob_rate by default.
767 */
768 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
769 false, !sample);
770
771 ar[2].count = 0;
772 ar[2].idx = -1;
773 } else {
774 /* Not using MRR, only use the first rate */
775 ar[1].count = 0;
776 ar[1].idx = -1;
777 }
778
779 mi->total_packets++;
780
781 /* wraparound */
782 if (mi->total_packets == ~0) {
783 mi->total_packets = 0;
784 mi->sample_packets = 0;
785 }
786 }
787
788 static void
789 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
790 struct ieee80211_supported_band *sband,
791 struct ieee80211_sta *sta)
792 {
793 int i;
794
795 if (sband->band != IEEE80211_BAND_2GHZ)
796 return;
797
798 mi->cck_supported = 0;
799 mi->cck_supported_short = 0;
800 for (i = 0; i < 4; i++) {
801 if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
802 continue;
803
804 mi->cck_supported |= BIT(i);
805 if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
806 mi->cck_supported_short |= BIT(i);
807 }
808
809 mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
810 }
811
812 static void
813 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
814 struct ieee80211_sta *sta, void *priv_sta)
815 {
816 struct minstrel_priv *mp = priv;
817 struct minstrel_ht_sta_priv *msp = priv_sta;
818 struct minstrel_ht_sta *mi = &msp->ht;
819 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
820 u16 sta_cap = sta->ht_cap.cap;
821 int n_supported = 0;
822 int ack_dur;
823 int stbc;
824 int i;
825
826 /* fall back to the old minstrel for legacy stations */
827 if (!sta->ht_cap.ht_supported)
828 goto use_legacy;
829
830 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
831 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
832
833 msp->is_ht = true;
834 memset(mi, 0, sizeof(*mi));
835 mi->stats_update = jiffies;
836
837 ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
838 mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
839 mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
840
841 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
842
843 /* When using MRR, sample more on the first attempt, without delay */
844 if (mp->has_mrr) {
845 mi->sample_count = 16;
846 mi->sample_wait = 0;
847 } else {
848 mi->sample_count = 8;
849 mi->sample_wait = 8;
850 }
851 mi->sample_tries = 4;
852
853 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
854 IEEE80211_HT_CAP_RX_STBC_SHIFT;
855 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
856
857 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
858 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
859
860 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
861 mi->groups[i].supported = 0;
862 if (i == MINSTREL_CCK_GROUP) {
863 minstrel_ht_update_cck(mp, mi, sband, sta);
864 continue;
865 }
866
867 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
868 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
869 if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
870 continue;
871 } else {
872 if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
873 continue;
874 }
875 }
876
877 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
878 sta->bandwidth < IEEE80211_STA_RX_BW_40)
879 continue;
880
881 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
882 if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
883 minstrel_mcs_groups[i].streams > 1)
884 continue;
885
886 mi->groups[i].supported =
887 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
888
889 if (mi->groups[i].supported)
890 n_supported++;
891 }
892
893 if (!n_supported)
894 goto use_legacy;
895
896 return;
897
898 use_legacy:
899 msp->is_ht = false;
900 memset(&msp->legacy, 0, sizeof(msp->legacy));
901 msp->legacy.r = msp->ratelist;
902 msp->legacy.sample_table = msp->sample_table;
903 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
904 }
905
906 static void
907 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
908 struct ieee80211_sta *sta, void *priv_sta)
909 {
910 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
911 }
912
913 static void
914 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
915 struct ieee80211_sta *sta, void *priv_sta,
916 u32 changed)
917 {
918 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
919 }
920
921 static void *
922 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
923 {
924 struct ieee80211_supported_band *sband;
925 struct minstrel_ht_sta_priv *msp;
926 struct minstrel_priv *mp = priv;
927 struct ieee80211_hw *hw = mp->hw;
928 int max_rates = 0;
929 int i;
930
931 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
932 sband = hw->wiphy->bands[i];
933 if (sband && sband->n_bitrates > max_rates)
934 max_rates = sband->n_bitrates;
935 }
936
937 msp = kzalloc(sizeof(*msp), gfp);
938 if (!msp)
939 return NULL;
940
941 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
942 if (!msp->ratelist)
943 goto error;
944
945 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
946 if (!msp->sample_table)
947 goto error1;
948
949 return msp;
950
951 error1:
952 kfree(msp->ratelist);
953 error:
954 kfree(msp);
955 return NULL;
956 }
957
958 static void
959 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
960 {
961 struct minstrel_ht_sta_priv *msp = priv_sta;
962
963 kfree(msp->sample_table);
964 kfree(msp->ratelist);
965 kfree(msp);
966 }
967
968 static void *
969 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
970 {
971 return mac80211_minstrel.alloc(hw, debugfsdir);
972 }
973
974 static void
975 minstrel_ht_free(void *priv)
976 {
977 mac80211_minstrel.free(priv);
978 }
979
980 static struct rate_control_ops mac80211_minstrel_ht = {
981 .name = "minstrel_ht",
982 .tx_status = minstrel_ht_tx_status,
983 .get_rate = minstrel_ht_get_rate,
984 .rate_init = minstrel_ht_rate_init,
985 .rate_update = minstrel_ht_rate_update,
986 .alloc_sta = minstrel_ht_alloc_sta,
987 .free_sta = minstrel_ht_free_sta,
988 .alloc = minstrel_ht_alloc,
989 .free = minstrel_ht_free,
990 #ifdef CONFIG_MAC80211_DEBUGFS
991 .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
992 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
993 #endif
994 };
995
996
997 static void
998 init_sample_table(void)
999 {
1000 int col, i, new_idx;
1001 u8 rnd[MCS_GROUP_RATES];
1002
1003 memset(sample_table, 0xff, sizeof(sample_table));
1004 for (col = 0; col < SAMPLE_COLUMNS; col++) {
1005 for (i = 0; i < MCS_GROUP_RATES; i++) {
1006 get_random_bytes(rnd, sizeof(rnd));
1007 new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
1008
1009 while (sample_table[col][new_idx] != 0xff)
1010 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
1011
1012 sample_table[col][new_idx] = i;
1013 }
1014 }
1015 }
1016
1017 int __init
1018 rc80211_minstrel_ht_init(void)
1019 {
1020 init_sample_table();
1021 return ieee80211_rate_control_register(&mac80211_minstrel_ht);
1022 }
1023
1024 void
1025 rc80211_minstrel_ht_exit(void)
1026 {
1027 ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
1028 }
Linux kernel - Deliverables
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