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authorJames Morris <james.l.morris@oracle.com>2014-11-19 05:32:12 -0500
committerJames Morris <james.l.morris@oracle.com>2014-11-19 05:32:12 -0500
commitb10778a00d40b3d9fdaaf5891e802794781ff71c (patch)
tree6ba4cbac86eecedc3f30650e7f764ecf00c83898 /net/mac80211/rc80211_pid_algo.c
parent594081ee7145cc30a3977cb4e218f81213b63dc5 (diff)
parentbfe01a5ba2490f299e1d2d5508cbbbadd897bbe9 (diff)
Merge commit 'v3.17' into next
Diffstat (limited to 'net/mac80211/rc80211_pid_algo.c')
-rw-r--r--net/mac80211/rc80211_pid_algo.c478
1 files changed, 0 insertions, 478 deletions
diff --git a/net/mac80211/rc80211_pid_algo.c b/net/mac80211/rc80211_pid_algo.c
deleted file mode 100644
index d0da2a70fe68..000000000000
--- a/net/mac80211/rc80211_pid_algo.c
+++ /dev/null
@@ -1,478 +0,0 @@
1/*
2 * Copyright 2002-2005, Instant802 Networks, Inc.
3 * Copyright 2005, Devicescape Software, Inc.
4 * Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de>
5 * Copyright 2007-2008, Stefano Brivio <stefano.brivio@polimi.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/netdevice.h>
13#include <linux/types.h>
14#include <linux/skbuff.h>
15#include <linux/debugfs.h>
16#include <linux/slab.h>
17#include <net/mac80211.h>
18#include "rate.h"
19#include "mesh.h"
20#include "rc80211_pid.h"
21
22
23/* This is an implementation of a TX rate control algorithm that uses a PID
24 * controller. Given a target failed frames rate, the controller decides about
25 * TX rate changes to meet the target failed frames rate.
26 *
27 * The controller basically computes the following:
28 *
29 * adj = CP * err + CI * err_avg + CD * (err - last_err) * (1 + sharpening)
30 *
31 * where
32 * adj adjustment value that is used to switch TX rate (see below)
33 * err current error: target vs. current failed frames percentage
34 * last_err last error
35 * err_avg average (i.e. poor man's integral) of recent errors
36 * sharpening non-zero when fast response is needed (i.e. right after
37 * association or no frames sent for a long time), heading
38 * to zero over time
39 * CP Proportional coefficient
40 * CI Integral coefficient
41 * CD Derivative coefficient
42 *
43 * CP, CI, CD are subject to careful tuning.
44 *
45 * The integral component uses a exponential moving average approach instead of
46 * an actual sliding window. The advantage is that we don't need to keep an
47 * array of the last N error values and computation is easier.
48 *
49 * Once we have the adj value, we map it to a rate by means of a learning
50 * algorithm. This algorithm keeps the state of the percentual failed frames
51 * difference between rates. The behaviour of the lowest available rate is kept
52 * as a reference value, and every time we switch between two rates, we compute
53 * the difference between the failed frames each rate exhibited. By doing so,
54 * we compare behaviours which different rates exhibited in adjacent timeslices,
55 * thus the comparison is minimally affected by external conditions. This
56 * difference gets propagated to the whole set of measurements, so that the
57 * reference is always the same. Periodically, we normalize this set so that
58 * recent events weigh the most. By comparing the adj value with this set, we
59 * avoid pejorative switches to lower rates and allow for switches to higher
60 * rates if they behaved well.
61 *
62 * Note that for the computations we use a fixed-point representation to avoid
63 * floating point arithmetic. Hence, all values are shifted left by
64 * RC_PID_ARITH_SHIFT.
65 */
66
67
68/* Adjust the rate while ensuring that we won't switch to a lower rate if it
69 * exhibited a worse failed frames behaviour and we'll choose the highest rate
70 * whose failed frames behaviour is not worse than the one of the original rate
71 * target. While at it, check that the new rate is valid. */
72static void rate_control_pid_adjust_rate(struct ieee80211_supported_band *sband,
73 struct ieee80211_sta *sta,
74 struct rc_pid_sta_info *spinfo, int adj,
75 struct rc_pid_rateinfo *rinfo)
76{
77 int cur_sorted, new_sorted, probe, tmp, n_bitrates, band;
78 int cur = spinfo->txrate_idx;
79
80 band = sband->band;
81 n_bitrates = sband->n_bitrates;
82
83 /* Map passed arguments to sorted values. */
84 cur_sorted = rinfo[cur].rev_index;
85 new_sorted = cur_sorted + adj;
86
87 /* Check limits. */
88 if (new_sorted < 0)
89 new_sorted = rinfo[0].rev_index;
90 else if (new_sorted >= n_bitrates)
91 new_sorted = rinfo[n_bitrates - 1].rev_index;
92
93 tmp = new_sorted;
94
95 if (adj < 0) {
96 /* Ensure that the rate decrease isn't disadvantageous. */
97 for (probe = cur_sorted; probe >= new_sorted; probe--)
98 if (rinfo[probe].diff <= rinfo[cur_sorted].diff &&
99 rate_supported(sta, band, rinfo[probe].index))
100 tmp = probe;
101 } else {
102 /* Look for rate increase with zero (or below) cost. */
103 for (probe = new_sorted + 1; probe < n_bitrates; probe++)
104 if (rinfo[probe].diff <= rinfo[new_sorted].diff &&
105 rate_supported(sta, band, rinfo[probe].index))
106 tmp = probe;
107 }
108
109 /* Fit the rate found to the nearest supported rate. */
110 do {
111 if (rate_supported(sta, band, rinfo[tmp].index)) {
112 spinfo->txrate_idx = rinfo[tmp].index;
113 break;
114 }
115 if (adj < 0)
116 tmp--;
117 else
118 tmp++;
119 } while (tmp < n_bitrates && tmp >= 0);
120
121#ifdef CONFIG_MAC80211_DEBUGFS
122 rate_control_pid_event_rate_change(&spinfo->events,
123 spinfo->txrate_idx,
124 sband->bitrates[spinfo->txrate_idx].bitrate);
125#endif
126}
127
128/* Normalize the failed frames per-rate differences. */
129static void rate_control_pid_normalize(struct rc_pid_info *pinfo, int l)
130{
131 int i, norm_offset = pinfo->norm_offset;
132 struct rc_pid_rateinfo *r = pinfo->rinfo;
133
134 if (r[0].diff > norm_offset)
135 r[0].diff -= norm_offset;
136 else if (r[0].diff < -norm_offset)
137 r[0].diff += norm_offset;
138 for (i = 0; i < l - 1; i++)
139 if (r[i + 1].diff > r[i].diff + norm_offset)
140 r[i + 1].diff -= norm_offset;
141 else if (r[i + 1].diff <= r[i].diff)
142 r[i + 1].diff += norm_offset;
143}
144
145static void rate_control_pid_sample(struct rc_pid_info *pinfo,
146 struct ieee80211_supported_band *sband,
147 struct ieee80211_sta *sta,
148 struct rc_pid_sta_info *spinfo)
149{
150 struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
151 u32 pf;
152 s32 err_avg;
153 u32 err_prop;
154 u32 err_int;
155 u32 err_der;
156 int adj, i, j, tmp;
157 unsigned long period;
158
159 /* In case nothing happened during the previous control interval, turn
160 * the sharpening factor on. */
161 period = msecs_to_jiffies(pinfo->sampling_period);
162 if (jiffies - spinfo->last_sample > 2 * period)
163 spinfo->sharp_cnt = pinfo->sharpen_duration;
164
165 spinfo->last_sample = jiffies;
166
167 /* This should never happen, but in case, we assume the old sample is
168 * still a good measurement and copy it. */
169 if (unlikely(spinfo->tx_num_xmit == 0))
170 pf = spinfo->last_pf;
171 else
172 pf = spinfo->tx_num_failed * 100 / spinfo->tx_num_xmit;
173
174 spinfo->tx_num_xmit = 0;
175 spinfo->tx_num_failed = 0;
176
177 /* If we just switched rate, update the rate behaviour info. */
178 if (pinfo->oldrate != spinfo->txrate_idx) {
179
180 i = rinfo[pinfo->oldrate].rev_index;
181 j = rinfo[spinfo->txrate_idx].rev_index;
182
183 tmp = (pf - spinfo->last_pf);
184 tmp = RC_PID_DO_ARITH_RIGHT_SHIFT(tmp, RC_PID_ARITH_SHIFT);
185
186 rinfo[j].diff = rinfo[i].diff + tmp;
187 pinfo->oldrate = spinfo->txrate_idx;
188 }
189 rate_control_pid_normalize(pinfo, sband->n_bitrates);
190
191 /* Compute the proportional, integral and derivative errors. */
192 err_prop = (pinfo->target - pf) << RC_PID_ARITH_SHIFT;
193
194 err_avg = spinfo->err_avg_sc >> pinfo->smoothing_shift;
195 spinfo->err_avg_sc = spinfo->err_avg_sc - err_avg + err_prop;
196 err_int = spinfo->err_avg_sc >> pinfo->smoothing_shift;
197
198 err_der = (pf - spinfo->last_pf) *
199 (1 + pinfo->sharpen_factor * spinfo->sharp_cnt);
200 spinfo->last_pf = pf;
201 if (spinfo->sharp_cnt)
202 spinfo->sharp_cnt--;
203
204#ifdef CONFIG_MAC80211_DEBUGFS
205 rate_control_pid_event_pf_sample(&spinfo->events, pf, err_prop, err_int,
206 err_der);
207#endif
208
209 /* Compute the controller output. */
210 adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i
211 + err_der * pinfo->coeff_d);
212 adj = RC_PID_DO_ARITH_RIGHT_SHIFT(adj, 2 * RC_PID_ARITH_SHIFT);
213
214 /* Change rate. */
215 if (adj)
216 rate_control_pid_adjust_rate(sband, sta, spinfo, adj, rinfo);
217}
218
219static void rate_control_pid_tx_status(void *priv, struct ieee80211_supported_band *sband,
220 struct ieee80211_sta *sta, void *priv_sta,
221 struct sk_buff *skb)
222{
223 struct rc_pid_info *pinfo = priv;
224 struct rc_pid_sta_info *spinfo = priv_sta;
225 unsigned long period;
226 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
227
228 if (!spinfo)
229 return;
230
231 /* Ignore all frames that were sent with a different rate than the rate
232 * we currently advise mac80211 to use. */
233 if (info->status.rates[0].idx != spinfo->txrate_idx)
234 return;
235
236 spinfo->tx_num_xmit++;
237
238#ifdef CONFIG_MAC80211_DEBUGFS
239 rate_control_pid_event_tx_status(&spinfo->events, info);
240#endif
241
242 /* We count frames that totally failed to be transmitted as two bad
243 * frames, those that made it out but had some retries as one good and
244 * one bad frame. */
245 if (!(info->flags & IEEE80211_TX_STAT_ACK)) {
246 spinfo->tx_num_failed += 2;
247 spinfo->tx_num_xmit++;
248 } else if (info->status.rates[0].count > 1) {
249 spinfo->tx_num_failed++;
250 spinfo->tx_num_xmit++;
251 }
252
253 /* Update PID controller state. */
254 period = msecs_to_jiffies(pinfo->sampling_period);
255 if (time_after(jiffies, spinfo->last_sample + period))
256 rate_control_pid_sample(pinfo, sband, sta, spinfo);
257}
258
259static void
260rate_control_pid_get_rate(void *priv, struct ieee80211_sta *sta,
261 void *priv_sta,
262 struct ieee80211_tx_rate_control *txrc)
263{
264 struct sk_buff *skb = txrc->skb;
265 struct ieee80211_supported_band *sband = txrc->sband;
266 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
267 struct rc_pid_sta_info *spinfo = priv_sta;
268 int rateidx;
269
270 if (txrc->rts)
271 info->control.rates[0].count =
272 txrc->hw->conf.long_frame_max_tx_count;
273 else
274 info->control.rates[0].count =
275 txrc->hw->conf.short_frame_max_tx_count;
276
277 /* Send management frames and NO_ACK data using lowest rate. */
278 if (rate_control_send_low(sta, priv_sta, txrc))
279 return;
280
281 rateidx = spinfo->txrate_idx;
282
283 if (rateidx >= sband->n_bitrates)
284 rateidx = sband->n_bitrates - 1;
285
286 info->control.rates[0].idx = rateidx;
287
288#ifdef CONFIG_MAC80211_DEBUGFS
289 rate_control_pid_event_tx_rate(&spinfo->events,
290 rateidx, sband->bitrates[rateidx].bitrate);
291#endif
292}
293
294static void
295rate_control_pid_rate_init(void *priv, struct ieee80211_supported_band *sband,
296 struct cfg80211_chan_def *chandef,
297 struct ieee80211_sta *sta, void *priv_sta)
298{
299 struct rc_pid_sta_info *spinfo = priv_sta;
300 struct rc_pid_info *pinfo = priv;
301 struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
302 int i, j, tmp;
303 bool s;
304
305 /* TODO: This routine should consider using RSSI from previous packets
306 * as we need to have IEEE 802.1X auth succeed immediately after assoc..
307 * Until that method is implemented, we will use the lowest supported
308 * rate as a workaround. */
309
310 /* Sort the rates. This is optimized for the most common case (i.e.
311 * almost-sorted CCK+OFDM rates). Kind of bubble-sort with reversed
312 * mapping too. */
313 for (i = 0; i < sband->n_bitrates; i++) {
314 rinfo[i].index = i;
315 rinfo[i].rev_index = i;
316 if (RC_PID_FAST_START)
317 rinfo[i].diff = 0;
318 else
319 rinfo[i].diff = i * pinfo->norm_offset;
320 }
321 for (i = 1; i < sband->n_bitrates; i++) {
322 s = false;
323 for (j = 0; j < sband->n_bitrates - i; j++)
324 if (unlikely(sband->bitrates[rinfo[j].index].bitrate >
325 sband->bitrates[rinfo[j + 1].index].bitrate)) {
326 tmp = rinfo[j].index;
327 rinfo[j].index = rinfo[j + 1].index;
328 rinfo[j + 1].index = tmp;
329 rinfo[rinfo[j].index].rev_index = j;
330 rinfo[rinfo[j + 1].index].rev_index = j + 1;
331 s = true;
332 }
333 if (!s)
334 break;
335 }
336
337 spinfo->txrate_idx = rate_lowest_index(sband, sta);
338}
339
340static void *rate_control_pid_alloc(struct ieee80211_hw *hw,
341 struct dentry *debugfsdir)
342{
343 struct rc_pid_info *pinfo;
344 struct rc_pid_rateinfo *rinfo;
345 struct ieee80211_supported_band *sband;
346 int i, max_rates = 0;
347#ifdef CONFIG_MAC80211_DEBUGFS
348 struct rc_pid_debugfs_entries *de;
349#endif
350
351 pinfo = kmalloc(sizeof(*pinfo), GFP_ATOMIC);
352 if (!pinfo)
353 return NULL;
354
355 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
356 sband = hw->wiphy->bands[i];
357 if (sband && sband->n_bitrates > max_rates)
358 max_rates = sband->n_bitrates;
359 }
360
361 rinfo = kmalloc(sizeof(*rinfo) * max_rates, GFP_ATOMIC);
362 if (!rinfo) {
363 kfree(pinfo);
364 return NULL;
365 }
366
367 pinfo->target = RC_PID_TARGET_PF;
368 pinfo->sampling_period = RC_PID_INTERVAL;
369 pinfo->coeff_p = RC_PID_COEFF_P;
370 pinfo->coeff_i = RC_PID_COEFF_I;
371 pinfo->coeff_d = RC_PID_COEFF_D;
372 pinfo->smoothing_shift = RC_PID_SMOOTHING_SHIFT;
373 pinfo->sharpen_factor = RC_PID_SHARPENING_FACTOR;
374 pinfo->sharpen_duration = RC_PID_SHARPENING_DURATION;
375 pinfo->norm_offset = RC_PID_NORM_OFFSET;
376 pinfo->rinfo = rinfo;
377 pinfo->oldrate = 0;
378
379#ifdef CONFIG_MAC80211_DEBUGFS
380 de = &pinfo->dentries;
381 de->target = debugfs_create_u32("target_pf", S_IRUSR | S_IWUSR,
382 debugfsdir, &pinfo->target);
383 de->sampling_period = debugfs_create_u32("sampling_period",
384 S_IRUSR | S_IWUSR, debugfsdir,
385 &pinfo->sampling_period);
386 de->coeff_p = debugfs_create_u32("coeff_p", S_IRUSR | S_IWUSR,
387 debugfsdir, (u32 *)&pinfo->coeff_p);
388 de->coeff_i = debugfs_create_u32("coeff_i", S_IRUSR | S_IWUSR,
389 debugfsdir, (u32 *)&pinfo->coeff_i);
390 de->coeff_d = debugfs_create_u32("coeff_d", S_IRUSR | S_IWUSR,
391 debugfsdir, (u32 *)&pinfo->coeff_d);
392 de->smoothing_shift = debugfs_create_u32("smoothing_shift",
393 S_IRUSR | S_IWUSR, debugfsdir,
394 &pinfo->smoothing_shift);
395 de->sharpen_factor = debugfs_create_u32("sharpen_factor",
396 S_IRUSR | S_IWUSR, debugfsdir,
397 &pinfo->sharpen_factor);
398 de->sharpen_duration = debugfs_create_u32("sharpen_duration",
399 S_IRUSR | S_IWUSR, debugfsdir,
400 &pinfo->sharpen_duration);
401 de->norm_offset = debugfs_create_u32("norm_offset",
402 S_IRUSR | S_IWUSR, debugfsdir,
403 &pinfo->norm_offset);
404#endif
405
406 return pinfo;
407}
408
409static void rate_control_pid_free(void *priv)
410{
411 struct rc_pid_info *pinfo = priv;
412#ifdef CONFIG_MAC80211_DEBUGFS
413 struct rc_pid_debugfs_entries *de = &pinfo->dentries;
414
415 debugfs_remove(de->norm_offset);
416 debugfs_remove(de->sharpen_duration);
417 debugfs_remove(de->sharpen_factor);
418 debugfs_remove(de->smoothing_shift);
419 debugfs_remove(de->coeff_d);
420 debugfs_remove(de->coeff_i);
421 debugfs_remove(de->coeff_p);
422 debugfs_remove(de->sampling_period);
423 debugfs_remove(de->target);
424#endif
425
426 kfree(pinfo->rinfo);
427 kfree(pinfo);
428}
429
430static void *rate_control_pid_alloc_sta(void *priv, struct ieee80211_sta *sta,
431 gfp_t gfp)
432{
433 struct rc_pid_sta_info *spinfo;
434
435 spinfo = kzalloc(sizeof(*spinfo), gfp);
436 if (spinfo == NULL)
437 return NULL;
438
439 spinfo->last_sample = jiffies;
440
441#ifdef CONFIG_MAC80211_DEBUGFS
442 spin_lock_init(&spinfo->events.lock);
443 init_waitqueue_head(&spinfo->events.waitqueue);
444#endif
445
446 return spinfo;
447}
448
449static void rate_control_pid_free_sta(void *priv, struct ieee80211_sta *sta,
450 void *priv_sta)
451{
452 kfree(priv_sta);
453}
454
455static const struct rate_control_ops mac80211_rcpid = {
456 .name = "pid",
457 .tx_status = rate_control_pid_tx_status,
458 .get_rate = rate_control_pid_get_rate,
459 .rate_init = rate_control_pid_rate_init,
460 .alloc = rate_control_pid_alloc,
461 .free = rate_control_pid_free,
462 .alloc_sta = rate_control_pid_alloc_sta,
463 .free_sta = rate_control_pid_free_sta,
464#ifdef CONFIG_MAC80211_DEBUGFS
465 .add_sta_debugfs = rate_control_pid_add_sta_debugfs,
466 .remove_sta_debugfs = rate_control_pid_remove_sta_debugfs,
467#endif
468};
469
470int __init rc80211_pid_init(void)
471{
472 return ieee80211_rate_control_register(&mac80211_rcpid);
473}
474
475void rc80211_pid_exit(void)
476{
477 ieee80211_rate_control_unregister(&mac80211_rcpid);
478}
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