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authorFelix Fietkau <nbd@openwrt.org>2008-10-05 12:07:45 -0400
committerJohn W. Linville <linville@tuxdriver.com>2008-10-06 18:14:57 -0400
commitcccf129f820e431d84690729254a32f1709328fb (patch)
tree0539c013be61ba6c8eeb0790ccb7df50bf2cb3bd /net/mac80211/rc80211_minstrel.c
parent2f7fe87034298d94301315ba4bb65c7284c709d0 (diff)
mac80211: add the 'minstrel' rate control algorithm
Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net/mac80211/rc80211_minstrel.c')
-rw-r--r--net/mac80211/rc80211_minstrel.c583
1 files changed, 583 insertions, 0 deletions
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
new file mode 100644
index 000000000000..f6d69dab07a3
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel.c
@@ -0,0 +1,583 @@
1/*
2 * Copyright (C) 2008 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 * Based on minstrel.c:
9 * Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
10 * Sponsored by Indranet Technologies Ltd
11 *
12 * Based on sample.c:
13 * Copyright (c) 2005 John Bicket
14 * All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
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.
29 *
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.
33 *
34 * NO WARRANTY
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.
46 */
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>
54#include "rate.h"
55#include "rc80211_minstrel.h"
56
57#define SAMPLE_COLUMNS 10
58#define SAMPLE_TBL(_mi, _idx, _col) \
59 _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
60
61/* convert mac80211 rate index to local array index */
62static inline int
63rix_to_ndx(struct minstrel_sta_info *mi, int rix)
64{
65 int i = rix;
66 for (i = rix; i >= 0; i--)
67 if (mi->r[i].rix == rix)
68 break;
69 WARN_ON(mi->r[i].rix != rix);
70 return i;
71}
72
73static inline bool
74use_low_rate(struct sk_buff *skb)
75{
76 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
77 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
78 u16 fc;
79
80 fc = le16_to_cpu(hdr->frame_control);
81
82 return ((info->flags & IEEE80211_TX_CTL_NO_ACK) ||
83 (fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
84 is_multicast_ether_addr(hdr->addr1));
85}
86
87
88static void
89minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
90{
91 u32 max_tp = 0, index_max_tp = 0, index_max_tp2 = 0;
92 u32 max_prob = 0, index_max_prob = 0;
93 u32 usecs;
94 u32 p;
95 int i;
96
97 mi->stats_update = jiffies;
98 for (i = 0; i < mi->n_rates; i++) {
99 struct minstrel_rate *mr = &mi->r[i];
100
101 usecs = mr->perfect_tx_time;
102 if (!usecs)
103 usecs = 1000000;
104
105 /* To avoid rounding issues, probabilities scale from 0 (0%)
106 * to 18000 (100%) */
107 if (mr->attempts) {
108 p = (mr->success * 18000) / mr->attempts;
109 mr->succ_hist += mr->success;
110 mr->att_hist += mr->attempts;
111 mr->cur_prob = p;
112 p = ((p * (100 - mp->ewma_level)) + (mr->probability *
113 mp->ewma_level)) / 100;
114 mr->probability = p;
115 mr->cur_tp = p * (1000000 / usecs);
116 }
117
118 mr->last_success = mr->success;
119 mr->last_attempts = mr->attempts;
120 mr->success = 0;
121 mr->attempts = 0;
122
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;
129 } else {
130 mr->adjusted_retry_count = mr->retry_count;
131 }
132 if (!mr->adjusted_retry_count)
133 mr->adjusted_retry_count = 2;
134 }
135
136 for (i = 0; i < mi->n_rates; i++) {
137 struct minstrel_rate *mr = &mi->r[i];
138 if (max_tp < mr->cur_tp) {
139 index_max_tp = i;
140 max_tp = mr->cur_tp;
141 }
142 if (max_prob < mr->probability) {
143 index_max_prob = i;
144 max_prob = mr->probability;
145 }
146 }
147
148 max_tp = 0;
149 for (i = 0; i < mi->n_rates; i++) {
150 struct minstrel_rate *mr = &mi->r[i];
151
152 if (i == index_max_tp)
153 continue;
154
155 if (max_tp < mr->cur_tp) {
156 index_max_tp2 = i;
157 max_tp = mr->cur_tp;
158 }
159 }
160 mi->max_tp_rate = index_max_tp;
161 mi->max_tp_rate2 = index_max_tp2;
162 mi->max_prob_rate = index_max_prob;
163}
164
165static void
166minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
167 struct ieee80211_sta *sta, void *priv_sta,
168 struct sk_buff *skb)
169{
170 struct minstrel_sta_info *mi = priv_sta;
171 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
172 struct ieee80211_tx_altrate *ar = info->status.retries;
173 struct minstrel_priv *mp = priv;
174 int i, ndx, tries;
175 int success = 0;
176
177 if (!info->status.excessive_retries)
178 success = 1;
179
180 if (!mp->has_mrr || (ar[0].rate_idx < 0)) {
181 ndx = rix_to_ndx(mi, info->tx_rate_idx);
182 tries = info->status.retry_count + 1;
183 mi->r[ndx].success += success;
184 mi->r[ndx].attempts += tries;
185 return;
186 }
187
188 for (i = 0; i < 4; i++) {
189 if (ar[i].rate_idx < 0)
190 break;
191
192 ndx = rix_to_ndx(mi, ar[i].rate_idx);
193 mi->r[ndx].attempts += ar[i].limit + 1;
194
195 if ((i != 3) && (ar[i + 1].rate_idx < 0))
196 mi->r[ndx].success += success;
197 }
198
199 if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
200 mi->sample_count++;
201
202 if (mi->sample_deferred > 0)
203 mi->sample_deferred--;
204}
205
206
207static inline unsigned int
208minstrel_get_retry_count(struct minstrel_rate *mr,
209 struct ieee80211_tx_info *info)
210{
211 unsigned int retry = mr->adjusted_retry_count;
212
213 if (info->flags & IEEE80211_TX_CTL_USE_RTS_CTS)
214 retry = max(2U, min(mr->retry_count_rtscts, retry));
215 else if (info->flags & IEEE80211_TX_CTL_USE_CTS_PROTECT)
216 retry = max(2U, min(mr->retry_count_cts, retry));
217 return retry;
218}
219
220
221static int
222minstrel_get_next_sample(struct minstrel_sta_info *mi)
223{
224 unsigned int sample_ndx;
225 sample_ndx = SAMPLE_TBL(mi, mi->sample_idx, mi->sample_column);
226 mi->sample_idx++;
227 if (mi->sample_idx > (mi->n_rates - 2)) {
228 mi->sample_idx = 0;
229 mi->sample_column++;
230 if (mi->sample_column >= SAMPLE_COLUMNS)
231 mi->sample_column = 0;
232 }
233 return sample_ndx;
234}
235
236void
237minstrel_get_rate(void *priv, struct ieee80211_supported_band *sband,
238 struct ieee80211_sta *sta, void *priv_sta,
239 struct sk_buff *skb, struct rate_selection *sel)
240{
241 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
242 struct minstrel_sta_info *mi = priv_sta;
243 struct minstrel_priv *mp = priv;
244 struct ieee80211_tx_altrate *ar = info->control.retries;
245 unsigned int ndx, sample_ndx = 0;
246 bool mrr;
247 bool sample_slower = false;
248 bool sample = false;
249 int i, delta;
250 int mrr_ndx[3];
251 int sample_rate;
252
253 if (!sta || !mi || use_low_rate(skb)) {
254 sel->rate_idx = rate_lowest_index(sband, sta);
255 return;
256 }
257
258 mrr = mp->has_mrr;
259
260 /* mac80211 does not allow mrr for RTS/CTS */
261 if ((info->flags & IEEE80211_TX_CTL_USE_RTS_CTS) ||
262 (info->flags & IEEE80211_TX_CTL_USE_CTS_PROTECT))
263 mrr = false;
264
265 if (time_after(jiffies, mi->stats_update + (mp->update_interval *
266 HZ) / 1000))
267 minstrel_update_stats(mp, mi);
268
269 ndx = mi->max_tp_rate;
270
271 if (mrr)
272 sample_rate = mp->lookaround_rate_mrr;
273 else
274 sample_rate = mp->lookaround_rate;
275
276 mi->packet_count++;
277 delta = (mi->packet_count * sample_rate / 100) -
278 (mi->sample_count + mi->sample_deferred / 2);
279
280 /* delta > 0: sampling required */
281 if (delta > 0) {
282 if (mi->packet_count >= 10000) {
283 mi->sample_deferred = 0;
284 mi->sample_count = 0;
285 mi->packet_count = 0;
286 } else if (delta > mi->n_rates * 2) {
287 /* With multi-rate retry, not every planned sample
288 * attempt actually gets used, due to the way the retry
289 * chain is set up - [max_tp,sample,prob,lowest] for
290 * sample_rate < max_tp.
291 *
292 * If there's too much sampling backlog and the link
293 * starts getting worse, minstrel would start bursting
294 * out lots of sampling frames, which would result
295 * in a large throughput loss. */
296 mi->sample_count += (delta - mi->n_rates * 2);
297 }
298
299 sample_ndx = minstrel_get_next_sample(mi);
300 sample = true;
301 sample_slower = mrr && (mi->r[sample_ndx].perfect_tx_time >
302 mi->r[ndx].perfect_tx_time);
303
304 if (!sample_slower) {
305 ndx = sample_ndx;
306 mi->sample_count++;
307 } else {
308 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
309 * packets that have the sampling rate deferred to the
310 * second MRR stage. Increase the sample counter only
311 * if the deferred sample rate was actually used.
312 * Use the sample_deferred counter to make sure that
313 * the sampling is not done in large bursts */
314 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
315 mi->sample_deferred++;
316 }
317 }
318 sel->rate_idx = mi->r[ndx].rix;
319 info->control.retry_limit = minstrel_get_retry_count(&mi->r[ndx], info);
320
321 if (!mrr) {
322 ar[0].rate_idx = mi->lowest_rix;
323 ar[0].limit = mp->max_retry;
324 ar[1].rate_idx = -1;
325 return;
326 }
327
328 /* MRR setup */
329 if (sample) {
330 if (sample_slower)
331 mrr_ndx[0] = sample_ndx;
332 else
333 mrr_ndx[0] = mi->max_tp_rate;
334 } else {
335 mrr_ndx[0] = mi->max_tp_rate2;
336 }
337 mrr_ndx[1] = mi->max_prob_rate;
338 mrr_ndx[2] = 0;
339 for (i = 0; i < 3; i++) {
340 ar[i].rate_idx = mi->r[mrr_ndx[i]].rix;
341 ar[i].limit = mi->r[mrr_ndx[i]].adjusted_retry_count;
342 }
343}
344
345
346static void
347calc_rate_durations(struct minstrel_sta_info *mi, struct ieee80211_local *local,
348 struct minstrel_rate *d, struct ieee80211_rate *rate)
349{
350 int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
351
352 d->perfect_tx_time = ieee80211_frame_duration(local, 1200,
353 rate->bitrate, erp, 1);
354 d->ack_time = ieee80211_frame_duration(local, 10,
355 rate->bitrate, erp, 1);
356}
357
358static void
359init_sample_table(struct minstrel_sta_info *mi)
360{
361 unsigned int i, col, new_idx;
362 unsigned int n_srates = mi->n_rates - 1;
363 u8 rnd[8];
364
365 mi->sample_column = 0;
366 mi->sample_idx = 0;
367 memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates);
368
369 for (col = 0; col < SAMPLE_COLUMNS; col++) {
370 for (i = 0; i < n_srates; i++) {
371 get_random_bytes(rnd, sizeof(rnd));
372 new_idx = (i + rnd[i & 7]) % n_srates;
373
374 while (SAMPLE_TBL(mi, new_idx, col) != 0)
375 new_idx = (new_idx + 1) % n_srates;
376
377 /* Don't sample the slowest rate (i.e. slowest base
378 * rate). We must presume that the slowest rate works
379 * fine, or else other management frames will also be
380 * failing and the link will break */
381 SAMPLE_TBL(mi, new_idx, col) = i + 1;
382 }
383 }
384}
385
386static void
387minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
388 struct ieee80211_sta *sta, void *priv_sta)
389{
390 struct minstrel_sta_info *mi = priv_sta;
391 struct minstrel_priv *mp = priv;
392 struct minstrel_rate *mr_ctl;
393 unsigned int i, n = 0;
394 unsigned int t_slot = 9; /* FIXME: get real slot time */
395
396 mi->lowest_rix = rate_lowest_index(sband, sta);
397 mr_ctl = &mi->r[rix_to_ndx(mi, mi->lowest_rix)];
398 mi->sp_ack_dur = mr_ctl->ack_time;
399
400 for (i = 0; i < sband->n_bitrates; i++) {
401 struct minstrel_rate *mr = &mi->r[n];
402 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
403 unsigned int tx_time_single;
404 unsigned int cw = mp->cw_min;
405
406 if (!rate_supported(sta, sband->band, i))
407 continue;
408 n++;
409 memset(mr, 0, sizeof(*mr));
410
411 mr->rix = i;
412 mr->bitrate = sband->bitrates[i].bitrate / 5;
413 calc_rate_durations(mi, hw_to_local(mp->hw), mr,
414 &sband->bitrates[i]);
415
416 /* calculate maximum number of retransmissions before
417 * fallback (based on maximum segment size) */
418 mr->retry_count = 1;
419 mr->retry_count_cts = 1;
420 mr->retry_count_rtscts = 1;
421 tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
422 do {
423 /* add one retransmission */
424 tx_time_single = mr->ack_time + mr->perfect_tx_time;
425
426 /* contention window */
427 tx_time_single += t_slot + min(cw, mp->cw_max);
428 cw = (cw + 1) << 1;
429
430 tx_time += tx_time_single;
431 tx_time_cts += tx_time_single + mi->sp_ack_dur;
432 tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
433 if ((tx_time_cts < mp->segment_size) &&
434 (mr->retry_count_cts < mp->max_retry))
435 mr->retry_count_cts++;
436 if ((tx_time_rtscts < mp->segment_size) &&
437 (mr->retry_count_rtscts < mp->max_retry))
438 mr->retry_count_rtscts++;
439 } while ((tx_time < mp->segment_size) &&
440 (++mr->retry_count < mp->max_retry));
441 mr->adjusted_retry_count = mr->retry_count;
442 }
443
444 for (i = n; i < sband->n_bitrates; i++) {
445 struct minstrel_rate *mr = &mi->r[i];
446 mr->rix = -1;
447 }
448
449 mi->n_rates = n;
450 mi->stats_update = jiffies;
451
452 init_sample_table(mi);
453}
454
455static void *
456minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
457{
458 struct ieee80211_supported_band *sband;
459 struct minstrel_sta_info *mi;
460 struct minstrel_priv *mp = priv;
461 struct ieee80211_hw *hw = mp->hw;
462 int max_rates = 0;
463 int i;
464
465 mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
466 if (!mi)
467 return NULL;
468
469 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
470 sband = hw->wiphy->bands[hw->conf.channel->band];
471 if (sband->n_bitrates > max_rates)
472 max_rates = sband->n_bitrates;
473 }
474
475 mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
476 if (!mi->r)
477 goto error;
478
479 mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
480 if (!mi->sample_table)
481 goto error1;
482
483 mi->stats_update = jiffies;
484 return mi;
485
486error1:
487 kfree(mi->r);
488error:
489 kfree(mi);
490 return NULL;
491}
492
493static void
494minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
495{
496 struct minstrel_sta_info *mi = priv_sta;
497
498 kfree(mi->sample_table);
499 kfree(mi->r);
500 kfree(mi);
501}
502
503static void
504minstrel_clear(void *priv)
505{
506}
507
508static void *
509minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
510{
511 struct minstrel_priv *mp;
512
513 mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
514 if (!mp)
515 return NULL;
516
517 /* contention window settings
518 * Just an approximation. Using the per-queue values would complicate
519 * the calculations and is probably unnecessary */
520 mp->cw_min = 15;
521 mp->cw_max = 1023;
522
523 /* number of packets (in %) to use for sampling other rates
524 * sample less often for non-mrr packets, because the overhead
525 * is much higher than with mrr */
526 mp->lookaround_rate = 5;
527 mp->lookaround_rate_mrr = 10;
528
529 /* moving average weight for EWMA */
530 mp->ewma_level = 75;
531
532 /* maximum time that the hw is allowed to stay in one MRR segment */
533 mp->segment_size = 6000;
534
535 if (hw->max_altrate_tries > 0)
536 mp->max_retry = hw->max_altrate_tries;
537 else
538 /* safe default, does not necessarily have to match hw properties */
539 mp->max_retry = 7;
540
541 if (hw->max_altrates >= 3)
542 mp->has_mrr = true;
543
544 mp->hw = hw;
545 mp->update_interval = 100;
546
547 return mp;
548}
549
550static void
551minstrel_free(void *priv)
552{
553 kfree(priv);
554}
555
556static struct rate_control_ops mac80211_minstrel = {
557 .name = "minstrel",
558 .tx_status = minstrel_tx_status,
559 .get_rate = minstrel_get_rate,
560 .rate_init = minstrel_rate_init,
561 .clear = minstrel_clear,
562 .alloc = minstrel_alloc,
563 .free = minstrel_free,
564 .alloc_sta = minstrel_alloc_sta,
565 .free_sta = minstrel_free_sta,
566#ifdef CONFIG_MAC80211_DEBUGFS
567 .add_sta_debugfs = minstrel_add_sta_debugfs,
568 .remove_sta_debugfs = minstrel_remove_sta_debugfs,
569#endif
570};
571
572int __init
573rc80211_minstrel_init(void)
574{
575 return ieee80211_rate_control_register(&mac80211_minstrel);
576}
577
578void
579rc80211_minstrel_exit(void)
580{
581 ieee80211_rate_control_unregister(&mac80211_minstrel);
582}
583