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linux/net/mac80211/rc80211_minstrel_ht.c
Felix Fietkau 80d55154b2 mac80211: minstrel_ht: significantly redesign the rate probing strategy 
The biggest flaw in current minstrel_ht is the fact that it needs way too
many probing packets to be able to quickly find the best rate.
Depending on the wifi hardware and operating mode, this can significantly
reduce throughput when not operating at the highest available data rate.

In order to be able to significantly reduce the amount of rate sampling,
we need a much smarter selection of probing rates.

The new approach introduced by this patch maintains a limited set of
available rates to be tested during a statistics window.

They are split into distinct categories:
- MINSTREL_SAMPLE_TYPE_INC - incremental rate upgrade:
  Pick the next rate group and find the first rate that is faster than
  the current max. throughput rate
- MINSTREL_SAMPLE_TYPE_JUMP - random testing of higher rates:
  Pick a random rate from the next group that is faster than the current
  max throughput rate. This allows faster adaptation when the link changes
  significantly
- MINSTREL_SAMPLE_TYPE_SLOW - test a rate between max_prob, max_tp2 and
  max_tp in order to reduce the gap between them

In order to prioritize sampling, every 6 attempts are split into 3x INC,
2x JUMP, 1x SLOW.

Available rates are checked and refilled on every stats window update.

With this approach, we finally get a very small delta in throughput when
comparing setting the optimal data rate as a fixed rate vs normal rate
control operation.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210127055735.78599-4-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2021-02-12 08:57:45 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
* Copyright (C) 2019-2020 Intel Corporation
*/
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/debugfs.h>
#include <linux/random.h>
#include <linux/moduleparam.h>
#include <linux/ieee80211.h>
#include <net/mac80211.h>
#include "rate.h"
#include "sta_info.h"
#include "rc80211_minstrel_ht.h"
#define AVG_AMPDU_SIZE 16
#define AVG_PKT_SIZE 1200
#define SAMPLE_SWITCH_THR 100
/* Number of bits for an average sized packet */
#define MCS_NBITS ((AVG_PKT_SIZE * AVG_AMPDU_SIZE) << 3)
/* Number of symbols for a packet with (bps) bits per symbol */
#define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))
/* Transmission time (nanoseconds) for a packet containing (syms) symbols */
#define MCS_SYMBOL_TIME(sgi, syms) \
(sgi ? \
((syms) * 18000 + 4000) / 5 : /* syms * 3.6 us */ \
((syms) * 1000) << 2 /* syms * 4 us */ \
)
/* Transmit duration for the raw data part of an average sized packet */
#define MCS_DURATION(streams, sgi, bps) \
(MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps))) / AVG_AMPDU_SIZE)
#define BW_20 0
#define BW_40 1
#define BW_80 2
/*
* Define group sort order: HT40 -> SGI -> #streams
*/
#define GROUP_IDX(_streams, _sgi, _ht40) \
MINSTREL_HT_GROUP_0 + \
MINSTREL_MAX_STREAMS * 2 * _ht40 + \
MINSTREL_MAX_STREAMS * _sgi + \
_streams - 1
#define _MAX(a, b) (((a)>(b))?(a):(b))
#define GROUP_SHIFT(duration) \
_MAX(0, 16 - __builtin_clz(duration))
/* MCS rate information for an MCS group */
#define __MCS_GROUP(_streams, _sgi, _ht40, _s) \
[GROUP_IDX(_streams, _sgi, _ht40)] = { \
.streams = _streams, \
.shift = _s, \
.bw = _ht40, \
.flags = \
IEEE80211_TX_RC_MCS | \
(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
(_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
.duration = { \
MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) >> _s \
} \
}
#define MCS_GROUP_SHIFT(_streams, _sgi, _ht40) \
GROUP_SHIFT(MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26))
#define MCS_GROUP(_streams, _sgi, _ht40) \
__MCS_GROUP(_streams, _sgi, _ht40, \
MCS_GROUP_SHIFT(_streams, _sgi, _ht40))
#define VHT_GROUP_IDX(_streams, _sgi, _bw) \
(MINSTREL_VHT_GROUP_0 + \
MINSTREL_MAX_STREAMS * 2 * (_bw) + \
MINSTREL_MAX_STREAMS * (_sgi) + \
(_streams) - 1)
#define BW2VBPS(_bw, r3, r2, r1) \
(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)
#define __VHT_GROUP(_streams, _sgi, _bw, _s) \
[VHT_GROUP_IDX(_streams, _sgi, _bw)] = { \
.streams = _streams, \
.shift = _s, \
.bw = _bw, \
.flags = \
IEEE80211_TX_RC_VHT_MCS | \
(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH : \
_bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
.duration = { \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 117, 54, 26)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 234, 108, 52)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 351, 162, 78)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 468, 216, 104)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 702, 324, 156)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 936, 432, 208)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1053, 486, 234)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1170, 540, 260)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1404, 648, 312)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1560, 720, 346)) >> _s \
} \
}
#define VHT_GROUP_SHIFT(_streams, _sgi, _bw) \
GROUP_SHIFT(MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 117, 54, 26)))
#define VHT_GROUP(_streams, _sgi, _bw) \
__VHT_GROUP(_streams, _sgi, _bw, \
VHT_GROUP_SHIFT(_streams, _sgi, _bw))
#define CCK_DURATION(_bitrate, _short) \
(1000 * (10 /* SIFS */ + \
(_short ? 72 + 24 : 144 + 48) + \
(8 * (AVG_PKT_SIZE + 4) * 10) / (_bitrate)))
#define CCK_DURATION_LIST(_short, _s) \
CCK_DURATION(10, _short) >> _s, \
CCK_DURATION(20, _short) >> _s, \
CCK_DURATION(55, _short) >> _s, \
CCK_DURATION(110, _short) >> _s
#define __CCK_GROUP(_s) \
[MINSTREL_CCK_GROUP] = { \
.streams = 1, \
.flags = 0, \
.shift = _s, \
.duration = { \
CCK_DURATION_LIST(false, _s), \
CCK_DURATION_LIST(true, _s) \
} \
}
#define CCK_GROUP_SHIFT \
GROUP_SHIFT(CCK_DURATION(10, false))
#define CCK_GROUP __CCK_GROUP(CCK_GROUP_SHIFT)
#define OFDM_DURATION(_bitrate) \
(1000 * (16 /* SIFS + signal ext */ + \
16 /* T_PREAMBLE */ + \
4 /* T_SIGNAL */ + \
4 * (((16 + 80 * (AVG_PKT_SIZE + 4) + 6) / \
((_bitrate) * 4)))))
#define OFDM_DURATION_LIST(_s) \
OFDM_DURATION(60) >> _s, \
OFDM_DURATION(90) >> _s, \
OFDM_DURATION(120) >> _s, \
OFDM_DURATION(180) >> _s, \
OFDM_DURATION(240) >> _s, \
OFDM_DURATION(360) >> _s, \
OFDM_DURATION(480) >> _s, \
OFDM_DURATION(540) >> _s
#define __OFDM_GROUP(_s) \
[MINSTREL_OFDM_GROUP] = { \
.streams = 1, \
.flags = 0, \
.shift = _s, \
.duration = { \
OFDM_DURATION_LIST(_s), \
} \
}
#define OFDM_GROUP_SHIFT \
GROUP_SHIFT(OFDM_DURATION(60))
#define OFDM_GROUP __OFDM_GROUP(OFDM_GROUP_SHIFT)
static bool minstrel_vht_only = true;
module_param(minstrel_vht_only, bool, 0644);
MODULE_PARM_DESC(minstrel_vht_only,
"Use only VHT rates when VHT is supported by sta.");
/*
* To enable sufficiently targeted rate sampling, MCS rates are divided into
* groups, based on the number of streams and flags (HT40, SGI) that they
* use.
*
* Sortorder has to be fixed for GROUP_IDX macro to be applicable:
* BW -> SGI -> #streams
*/
const struct mcs_group minstrel_mcs_groups[] = {
MCS_GROUP(1, 0, BW_20),
MCS_GROUP(2, 0, BW_20),
MCS_GROUP(3, 0, BW_20),
MCS_GROUP(4, 0, BW_20),
MCS_GROUP(1, 1, BW_20),
MCS_GROUP(2, 1, BW_20),
MCS_GROUP(3, 1, BW_20),
MCS_GROUP(4, 1, BW_20),
MCS_GROUP(1, 0, BW_40),
MCS_GROUP(2, 0, BW_40),
MCS_GROUP(3, 0, BW_40),
MCS_GROUP(4, 0, BW_40),
MCS_GROUP(1, 1, BW_40),
MCS_GROUP(2, 1, BW_40),
MCS_GROUP(3, 1, BW_40),
MCS_GROUP(4, 1, BW_40),
CCK_GROUP,
OFDM_GROUP,
VHT_GROUP(1, 0, BW_20),
VHT_GROUP(2, 0, BW_20),
VHT_GROUP(3, 0, BW_20),
VHT_GROUP(4, 0, BW_20),
VHT_GROUP(1, 1, BW_20),
VHT_GROUP(2, 1, BW_20),
VHT_GROUP(3, 1, BW_20),
VHT_GROUP(4, 1, BW_20),
VHT_GROUP(1, 0, BW_40),
VHT_GROUP(2, 0, BW_40),
VHT_GROUP(3, 0, BW_40),
VHT_GROUP(4, 0, BW_40),
VHT_GROUP(1, 1, BW_40),
VHT_GROUP(2, 1, BW_40),
VHT_GROUP(3, 1, BW_40),
VHT_GROUP(4, 1, BW_40),
VHT_GROUP(1, 0, BW_80),
VHT_GROUP(2, 0, BW_80),
VHT_GROUP(3, 0, BW_80),
VHT_GROUP(4, 0, BW_80),
VHT_GROUP(1, 1, BW_80),
VHT_GROUP(2, 1, BW_80),
VHT_GROUP(3, 1, BW_80),
VHT_GROUP(4, 1, BW_80),
};
const s16 minstrel_cck_bitrates[4] = { 10, 20, 55, 110 };
const s16 minstrel_ofdm_bitrates[8] = { 60, 90, 120, 180, 240, 360, 480, 540 };
static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
static const u8 minstrel_sample_seq[] = {
MINSTREL_SAMPLE_TYPE_INC,
MINSTREL_SAMPLE_TYPE_JUMP,
MINSTREL_SAMPLE_TYPE_INC,
MINSTREL_SAMPLE_TYPE_JUMP,
MINSTREL_SAMPLE_TYPE_INC,
MINSTREL_SAMPLE_TYPE_SLOW,
};
static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
/*
* Some VHT MCSes are invalid (when Ndbps / Nes is not an integer)
* e.g for MCS9@20MHzx1Nss: Ndbps=8x52*(5/6) Nes=1
*
* Returns the valid mcs map for struct minstrel_mcs_group_data.supported
*/
static u16
minstrel_get_valid_vht_rates(int bw, int nss, __le16 mcs_map)
{
u16 mask = 0;
if (bw == BW_20) {
if (nss != 3 && nss != 6)
mask = BIT(9);
} else if (bw == BW_80) {
if (nss == 3 || nss == 7)
mask = BIT(6);
else if (nss == 6)
mask = BIT(9);
} else {
WARN_ON(bw != BW_40);
}
switch ((le16_to_cpu(mcs_map) >> (2 * (nss - 1))) & 3) {
case IEEE80211_VHT_MCS_SUPPORT_0_7:
mask |= 0x300;
break;
case IEEE80211_VHT_MCS_SUPPORT_0_8:
mask |= 0x200;
break;
case IEEE80211_VHT_MCS_SUPPORT_0_9:
break;
default:
mask = 0x3ff;
}
return 0x3ff & ~mask;
}
static bool
minstrel_ht_is_legacy_group(int group)
{
return group == MINSTREL_CCK_GROUP ||
group == MINSTREL_OFDM_GROUP;
}
/*
* Look up an MCS group index based on mac80211 rate information
*/
static int
minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
{
return GROUP_IDX((rate->idx / 8) + 1,
!!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
!!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
}
static int
minstrel_vht_get_group_idx(struct ieee80211_tx_rate *rate)
{
return VHT_GROUP_IDX(ieee80211_rate_get_vht_nss(rate),
!!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
!!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) +
2*!!(rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH));
}
static struct minstrel_rate_stats *
minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
struct ieee80211_tx_rate *rate)
{
int group, idx;
if (rate->flags & IEEE80211_TX_RC_MCS) {
group = minstrel_ht_get_group_idx(rate);
idx = rate->idx % 8;
goto out;
}
if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
group = minstrel_vht_get_group_idx(rate);
idx = ieee80211_rate_get_vht_mcs(rate);
goto out;
}
group = MINSTREL_CCK_GROUP;
for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) {
if (rate->idx != mp->cck_rates[idx])
continue;
/* short preamble */
if ((mi->supported[group] & BIT(idx + 4)) &&
(rate->flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE))
idx += 4;
goto out;
}
group = MINSTREL_OFDM_GROUP;
for (idx = 0; idx < ARRAY_SIZE(mp->ofdm_rates[0]); idx++)
if (rate->idx == mp->ofdm_rates[mi->band][idx])
goto out;
idx = 0;
out:
return &mi->groups[group].rates[idx];
}
static inline struct minstrel_rate_stats *
minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
{
return &mi->groups[MI_RATE_GROUP(index)].rates[MI_RATE_IDX(index)];
}
static inline int minstrel_get_duration(int index)
{
const struct mcs_group *group = &minstrel_mcs_groups[MI_RATE_GROUP(index)];
unsigned int duration = group->duration[MI_RATE_IDX(index)];
return duration << group->shift;
}
static unsigned int
minstrel_ht_avg_ampdu_len(struct minstrel_ht_sta *mi)
{
int duration;
if (mi->avg_ampdu_len)
return MINSTREL_TRUNC(mi->avg_ampdu_len);
if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(mi->max_tp_rate[0])))
return 1;
duration = minstrel_get_duration(mi->max_tp_rate[0]);
if (duration > 400 * 1000)
return 2;
if (duration > 250 * 1000)
return 4;
if (duration > 150 * 1000)
return 8;
return 16;
}
/*
* Return current throughput based on the average A-MPDU length, taking into
* account the expected number of retransmissions and their expected length
*/
int
minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
int prob_avg)
{
unsigned int nsecs = 0, overhead = mi->overhead;
unsigned int ampdu_len = 1;
/* do not account throughput if sucess prob is below 10% */
if (prob_avg < MINSTREL_FRAC(10, 100))
return 0;
if (minstrel_ht_is_legacy_group(group))
overhead = mi->overhead_legacy;
else
ampdu_len = minstrel_ht_avg_ampdu_len(mi);
nsecs = 1000 * overhead / ampdu_len;
nsecs += minstrel_mcs_groups[group].duration[rate] <<
minstrel_mcs_groups[group].shift;
/*
* For the throughput calculation, limit the probability value to 90% to
* account for collision related packet error rate fluctuation
* (prob is scaled - see MINSTREL_FRAC above)
*/
if (prob_avg > MINSTREL_FRAC(90, 100))
prob_avg = MINSTREL_FRAC(90, 100);
return MINSTREL_TRUNC(100 * ((prob_avg * 1000000) / nsecs));
}
/*
* Find & sort topmost throughput rates
*
* If multiple rates provide equal throughput the sorting is based on their
* current success probability. Higher success probability is preferred among
* MCS groups, CCK rates do not provide aggregation and are therefore at last.
*/
static void
minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
u16 *tp_list)
{
int cur_group, cur_idx, cur_tp_avg, cur_prob;
int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
int j = MAX_THR_RATES;
cur_group = MI_RATE_GROUP(index);
cur_idx = MI_RATE_IDX(index);
cur_prob = mi->groups[cur_group].rates[cur_idx].prob_avg;
cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx, cur_prob);
do {
tmp_group = MI_RATE_GROUP(tp_list[j - 1]);
tmp_idx = MI_RATE_IDX(tp_list[j - 1]);
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx,
tmp_prob);
if (cur_tp_avg < tmp_tp_avg ||
(cur_tp_avg == tmp_tp_avg && cur_prob <= tmp_prob))
break;
j--;
} while (j > 0);
if (j < MAX_THR_RATES - 1) {
memmove(&tp_list[j + 1], &tp_list[j], (sizeof(*tp_list) *
(MAX_THR_RATES - (j + 1))));
}
if (j < MAX_THR_RATES)
tp_list[j] = index;
}
/*
* Find and set the topmost probability rate per sta and per group
*/
static void
minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 *dest, u16 index)
{
struct minstrel_mcs_group_data *mg;
struct minstrel_rate_stats *mrs;
int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
int max_tp_group, max_tp_idx, max_tp_prob;
int cur_tp_avg, cur_group, cur_idx;
int max_gpr_group, max_gpr_idx;
int max_gpr_tp_avg, max_gpr_prob;
cur_group = MI_RATE_GROUP(index);
cur_idx = MI_RATE_IDX(index);
mg = &mi->groups[cur_group];
mrs = &mg->rates[cur_idx];
tmp_group = MI_RATE_GROUP(*dest);
tmp_idx = MI_RATE_IDX(*dest);
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
/* if max_tp_rate[0] is from MCS_GROUP max_prob_rate get selected from
* MCS_GROUP as well as CCK_GROUP rates do not allow aggregation */
max_tp_group = MI_RATE_GROUP(mi->max_tp_rate[0]);
max_tp_idx = MI_RATE_IDX(mi->max_tp_rate[0]);
max_tp_prob = mi->groups[max_tp_group].rates[max_tp_idx].prob_avg;
if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(index)) &&
!minstrel_ht_is_legacy_group(max_tp_group))
return;
/* skip rates faster than max tp rate with lower prob */
if (minstrel_get_duration(mi->max_tp_rate[0]) > minstrel_get_duration(index) &&
mrs->prob_avg < max_tp_prob)
return;
max_gpr_group = MI_RATE_GROUP(mg->max_group_prob_rate);
max_gpr_idx = MI_RATE_IDX(mg->max_group_prob_rate);
max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_avg;
if (mrs->prob_avg > MINSTREL_FRAC(75, 100)) {
cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx,
mrs->prob_avg);
if (cur_tp_avg > tmp_tp_avg)
*dest = index;
max_gpr_tp_avg = minstrel_ht_get_tp_avg(mi, max_gpr_group,
max_gpr_idx,
max_gpr_prob);
if (cur_tp_avg > max_gpr_tp_avg)
mg->max_group_prob_rate = index;
} else {
if (mrs->prob_avg > tmp_prob)
*dest = index;
if (mrs->prob_avg > max_gpr_prob)
mg->max_group_prob_rate = index;
}
}
/*
* Assign new rate set per sta and use CCK rates only if the fastest
* rate (max_tp_rate[0]) is from CCK group. This prohibits such sorted
* rate sets where MCS and CCK rates are mixed, because CCK rates can
* not use aggregation.
*/
static void
minstrel_ht_assign_best_tp_rates(struct minstrel_ht_sta *mi,
u16 tmp_mcs_tp_rate[MAX_THR_RATES],
u16 tmp_legacy_tp_rate[MAX_THR_RATES])
{
unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp, tmp_prob;
int i;
tmp_group = MI_RATE_GROUP(tmp_legacy_tp_rate[0]);
tmp_idx = MI_RATE_IDX(tmp_legacy_tp_rate[0]);
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
tmp_cck_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
tmp_group = MI_RATE_GROUP(tmp_mcs_tp_rate[0]);
tmp_idx = MI_RATE_IDX(tmp_mcs_tp_rate[0]);
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
if (tmp_cck_tp > tmp_mcs_tp) {
for(i = 0; i < MAX_THR_RATES; i++) {
minstrel_ht_sort_best_tp_rates(mi, tmp_legacy_tp_rate[i],
tmp_mcs_tp_rate);
}
}
}
/*
* Try to increase robustness of max_prob rate by decrease number of
* streams if possible.
*/
static inline void
minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
{
struct minstrel_mcs_group_data *mg;
int tmp_max_streams, group, tmp_idx, tmp_prob;
int tmp_tp = 0;
if (!mi->sta->ht_cap.ht_supported)
return;
group = MI_RATE_GROUP(mi->max_tp_rate[0]);
tmp_max_streams = minstrel_mcs_groups[group].streams;
for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
mg = &mi->groups[group];
if (!mi->supported[group] || group == MINSTREL_CCK_GROUP)
continue;
tmp_idx = MI_RATE_IDX(mg->max_group_prob_rate);
tmp_prob = mi->groups[group].rates[tmp_idx].prob_avg;
if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
(minstrel_mcs_groups[group].streams < tmp_max_streams)) {
mi->max_prob_rate = mg->max_group_prob_rate;
tmp_tp = minstrel_ht_get_tp_avg(mi, group,
tmp_idx,
tmp_prob);
}
}
}
static u16
__minstrel_ht_get_sample_rate(struct minstrel_ht_sta *mi,
enum minstrel_sample_type type)
{
u16 *rates = mi->sample[type].sample_rates;
u16 cur;
int i;
for (i = 0; i < MINSTREL_SAMPLE_RATES; i++) {
if (!rates[i])
continue;
cur = rates[i];
rates[i] = 0;
return cur;
}
return 0;
}
static void
minstrel_ht_rate_sample_switch(struct minstrel_priv *mp,
struct minstrel_ht_sta *mi)
{
u16 rate;
/*
* Use rate switching instead of probing packets for devices with
* little control over retry fallback behavior
*/
if (mp->hw->max_rates > 1)
return;
rate = __minstrel_ht_get_sample_rate(mi, MINSTREL_SAMPLE_TYPE_INC);
if (!rate)
return;
mi->sample_rate = rate;
mi->sample_mode = MINSTREL_SAMPLE_ACTIVE;
}
static inline int
minstrel_ewma(int old, int new, int weight)
{
int diff, incr;
diff = new - old;
incr = (EWMA_DIV - weight) * diff / EWMA_DIV;
return old + incr;
}
static inline int minstrel_filter_avg_add(u16 *prev_1, u16 *prev_2, s32 in)
{
s32 out_1 = *prev_1;
s32 out_2 = *prev_2;
s32 val;
if (!in)
in += 1;
if (!out_1) {
val = out_1 = in;
goto out;
}
val = MINSTREL_AVG_COEFF1 * in;
val += MINSTREL_AVG_COEFF2 * out_1;
val += MINSTREL_AVG_COEFF3 * out_2;
val >>= MINSTREL_SCALE;
if (val > 1 << MINSTREL_SCALE)
val = 1 << MINSTREL_SCALE;
if (val < 0)
val = 1;
out:
*prev_2 = out_1;
*prev_1 = val;
return val;
}
/*
* Recalculate statistics and counters of a given rate
*/
static void
minstrel_ht_calc_rate_stats(struct minstrel_priv *mp,
struct minstrel_rate_stats *mrs)
{
unsigned int cur_prob;
if (unlikely(mrs->attempts > 0)) {
cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
minstrel_filter_avg_add(&mrs->prob_avg,
&mrs->prob_avg_1, cur_prob);
mrs->att_hist += mrs->attempts;
mrs->succ_hist += mrs->success;
}
mrs->last_success = mrs->success;
mrs->last_attempts = mrs->attempts;
mrs->success = 0;
mrs->attempts = 0;
}
static bool
minstrel_ht_find_sample_rate(struct minstrel_ht_sta *mi, int type, int idx)
{
int i;
for (i = 0; i < MINSTREL_SAMPLE_RATES; i++) {
u16 cur = mi->sample[type].sample_rates[i];
if (cur == idx)
return true;
if (!cur)
break;
}
return false;
}
static int
minstrel_ht_move_sample_rates(struct minstrel_ht_sta *mi, int type,
u32 fast_rate_dur, u32 slow_rate_dur)
{
u16 *rates = mi->sample[type].sample_rates;
int i, j;
for (i = 0, j = 0; i < MINSTREL_SAMPLE_RATES; i++) {
u32 duration;
bool valid = false;
u16 cur;
cur = rates[i];
if (!cur)
continue;
duration = minstrel_get_duration(cur);
switch (type) {
case MINSTREL_SAMPLE_TYPE_SLOW:
valid = duration > fast_rate_dur &&
duration < slow_rate_dur;
break;
case MINSTREL_SAMPLE_TYPE_INC:
case MINSTREL_SAMPLE_TYPE_JUMP:
valid = duration < fast_rate_dur;
break;
default:
valid = false;
break;
}
if (!valid) {
rates[i] = 0;
continue;
}
if (i == j)
continue;
rates[j++] = cur;
rates[i] = 0;
}
return j;
}
static int
minstrel_ht_group_min_rate_offset(struct minstrel_ht_sta *mi, int group,
u32 max_duration)
{
u16 supported = mi->supported[group];
int i;
for (i = 0; i < MCS_GROUP_RATES && supported; i++, supported >>= 1) {
if (!(supported & BIT(0)))
continue;
if (minstrel_get_duration(MI_RATE(group, i)) >= max_duration)
continue;
return i;
}
return -1;
}
/*
* Incremental update rates:
* Flip through groups and pick the first group rate that is faster than the
* highest currently selected rate
*/
static u16
minstrel_ht_next_inc_rate(struct minstrel_ht_sta *mi, u32 fast_rate_dur)
{
struct minstrel_mcs_group_data *mg;
u8 type = MINSTREL_SAMPLE_TYPE_INC;
int i, index = 0;
u8 group;
group = mi->sample[type].sample_group;
for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
group = (group + 1) % ARRAY_SIZE(minstrel_mcs_groups);
mg = &mi->groups[group];
index = minstrel_ht_group_min_rate_offset(mi, group,
fast_rate_dur);
if (index < 0)
continue;
index = MI_RATE(group, index & 0xf);
if (!minstrel_ht_find_sample_rate(mi, type, index))
goto out;
}
index = 0;
out:
mi->sample[type].sample_group = group;
return index;
}
static int
minstrel_ht_next_group_sample_rate(struct minstrel_ht_sta *mi, int group,
u16 supported, int offset)
{
struct minstrel_mcs_group_data *mg = &mi->groups[group];
u16 idx;
int i;
for (i = 0; i < MCS_GROUP_RATES; i++) {
idx = sample_table[mg->column][mg->index];
if (++mg->index >= MCS_GROUP_RATES) {
mg->index = 0;
if (++mg->column >= ARRAY_SIZE(sample_table))
mg->column = 0;
}
if (idx < offset)
continue;
if (!(supported & BIT(idx)))
continue;
return MI_RATE(group, idx);
}
return -1;
}
/*
* Jump rates:
* Sample random rates, use those that are faster than the highest
* currently selected rate. Rates between the fastest and the slowest
* get sorted into the slow sample bucket, but only if it has room
*/
static u16
minstrel_ht_next_jump_rate(struct minstrel_ht_sta *mi, u32 fast_rate_dur,
u32 slow_rate_dur, int *slow_rate_ofs)
{
struct minstrel_mcs_group_data *mg;
struct minstrel_rate_stats *mrs;
u32 max_duration = slow_rate_dur;
int i, index, offset;
u16 *slow_rates;
u16 supported;
u32 duration;
u8 group;
if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
max_duration = fast_rate_dur;
slow_rates = mi->sample[MINSTREL_SAMPLE_TYPE_SLOW].sample_rates;
group = mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_group;
for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
u8 type;
group = (group + 1) % ARRAY_SIZE(minstrel_mcs_groups);
mg = &mi->groups[group];
supported = mi->supported[group];
if (!supported)
continue;
offset = minstrel_ht_group_min_rate_offset(mi, group,
max_duration);
if (offset < 0)
continue;
index = minstrel_ht_next_group_sample_rate(mi, group, supported,
offset);
if (index < 0)
continue;
duration = minstrel_get_duration(index);
if (duration < fast_rate_dur)
type = MINSTREL_SAMPLE_TYPE_JUMP;
else
type = MINSTREL_SAMPLE_TYPE_SLOW;
if (minstrel_ht_find_sample_rate(mi, type, index))
continue;
if (type == MINSTREL_SAMPLE_TYPE_JUMP)
goto found;
if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
continue;
if (duration >= slow_rate_dur)
continue;
/* skip slow rates with high success probability */
mrs = minstrel_get_ratestats(mi, index);
if (mrs->prob_avg > MINSTREL_FRAC(95, 100))
continue;
slow_rates[(*slow_rate_ofs)++] = index;
if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
max_duration = fast_rate_dur;
}
index = 0;
found:
mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_group = group;
return index;
}
static void
minstrel_ht_refill_sample_rates(struct minstrel_ht_sta *mi)
{
u32 prob_dur = minstrel_get_duration(mi->max_prob_rate);
u32 tp_dur = minstrel_get_duration(mi->max_tp_rate[0]);
u32 tp2_dur = minstrel_get_duration(mi->max_tp_rate[1]);
u32 fast_rate_dur = min(min(tp_dur, tp2_dur), prob_dur);
u32 slow_rate_dur = max(max(tp_dur, tp2_dur), prob_dur);
u16 *rates;
int i, j;
rates = mi->sample[MINSTREL_SAMPLE_TYPE_INC].sample_rates;
i = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_INC,
fast_rate_dur, slow_rate_dur);
while (i < MINSTREL_SAMPLE_RATES) {
rates[i] = minstrel_ht_next_inc_rate(mi, tp_dur);
if (!rates[i])
break;
i++;
}
rates = mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_rates;
i = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_JUMP,
fast_rate_dur, slow_rate_dur);
j = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_SLOW,
fast_rate_dur, slow_rate_dur);
while (i < MINSTREL_SAMPLE_RATES) {
rates[i] = minstrel_ht_next_jump_rate(mi, fast_rate_dur,
slow_rate_dur, &j);
if (!rates[i])
break;
i++;
}
for (i = 0; i < ARRAY_SIZE(mi->sample); i++)
memcpy(mi->sample[i].cur_sample_rates, mi->sample[i].sample_rates,
sizeof(mi->sample[i].cur_sample_rates));
}
/*
* Update rate statistics and select new primary rates
*
* Rules for rate selection:
* - max_prob_rate must use only one stream, as a tradeoff between delivery
* probability and throughput during strong fluctuations
* - as long as the max prob rate has a probability of more than 75%, pick
* higher throughput rates, even if the probablity is a bit lower
*/
static void
minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
bool sample)
{
struct minstrel_mcs_group_data *mg;
struct minstrel_rate_stats *mrs;
int group, i, j, cur_prob;
u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
u16 tmp_legacy_tp_rate[MAX_THR_RATES], tmp_max_prob_rate;
u16 index;
bool ht_supported = mi->sta->ht_cap.ht_supported;
mi->sample_mode = MINSTREL_SAMPLE_IDLE;
if (sample) {
mi->total_packets_cur = mi->total_packets -
mi->total_packets_last;
mi->total_packets_last = mi->total_packets;
}
if (!mp->sample_switch)
sample = false;
if (mi->total_packets_cur < SAMPLE_SWITCH_THR && mp->sample_switch != 1)
sample = false;
if (mi->ampdu_packets > 0) {
if (!ieee80211_hw_check(mp->hw, TX_STATUS_NO_AMPDU_LEN))
mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets),
EWMA_LEVEL);
else
mi->avg_ampdu_len = 0;
mi->ampdu_len = 0;
mi->ampdu_packets = 0;
}
if (mi->supported[MINSTREL_CCK_GROUP])
group = MINSTREL_CCK_GROUP;
else if (mi->supported[MINSTREL_OFDM_GROUP])
group = MINSTREL_OFDM_GROUP;
else
group = 0;
index = MI_RATE(group, 0);
for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
tmp_legacy_tp_rate[j] = index;
if (mi->supported[MINSTREL_VHT_GROUP_0])
group = MINSTREL_VHT_GROUP_0;
else if (ht_supported)
group = MINSTREL_HT_GROUP_0;
else if (mi->supported[MINSTREL_CCK_GROUP])
group = MINSTREL_CCK_GROUP;
else
group = MINSTREL_OFDM_GROUP;
index = MI_RATE(group, 0);
tmp_max_prob_rate = index;
for (j = 0; j < ARRAY_SIZE(tmp_mcs_tp_rate); j++)
tmp_mcs_tp_rate[j] = index;
/* Find best rate sets within all MCS groups*/
for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
u16 *tp_rate = tmp_mcs_tp_rate;
u16 last_prob = 0;
mg = &mi->groups[group];
if (!mi->supported[group])
continue;
/* (re)Initialize group rate indexes */
for(j = 0; j < MAX_THR_RATES; j++)
tmp_group_tp_rate[j] = MI_RATE(group, 0);
if (group == MINSTREL_CCK_GROUP && ht_supported)
tp_rate = tmp_legacy_tp_rate;
for (i = MCS_GROUP_RATES - 1; i >= 0; i--) {
if (!(mi->supported[group] & BIT(i)))
continue;
index = MI_RATE(group, i);
mrs = &mg->rates[i];
mrs->retry_updated = false;
minstrel_ht_calc_rate_stats(mp, mrs);
if (mrs->att_hist)
last_prob = max(last_prob, mrs->prob_avg);
else
mrs->prob_avg = max(last_prob, mrs->prob_avg);
cur_prob = mrs->prob_avg;
if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
continue;
/* Find max throughput rate set */
minstrel_ht_sort_best_tp_rates(mi, index, tp_rate);
/* Find max throughput rate set within a group */
minstrel_ht_sort_best_tp_rates(mi, index,
tmp_group_tp_rate);
}
memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
sizeof(mg->max_group_tp_rate));
}
/* Assign new rate set per sta */
minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate,
tmp_legacy_tp_rate);
memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));
for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
if (!mi->supported[group])
continue;
mg = &mi->groups[group];
mg->max_group_prob_rate = MI_RATE(group, 0);
for (i = 0; i < MCS_GROUP_RATES; i++) {
if (!(mi->supported[group] & BIT(i)))
continue;
index = MI_RATE(group, i);
/* Find max probability rate per group and global */
minstrel_ht_set_best_prob_rate(mi, &tmp_max_prob_rate,
index);
}
}
mi->max_prob_rate = tmp_max_prob_rate;
/* Try to increase robustness of max_prob_rate*/
minstrel_ht_prob_rate_reduce_streams(mi);
minstrel_ht_refill_sample_rates(mi);
if (sample)
minstrel_ht_rate_sample_switch(mp, mi);
#ifdef CONFIG_MAC80211_DEBUGFS
/* use fixed index if set */
if (mp->fixed_rate_idx != -1) {
for (i = 0; i < 4; i++)
mi->max_tp_rate[i] = mp->fixed_rate_idx;
mi->max_prob_rate = mp->fixed_rate_idx;
mi->sample_mode = MINSTREL_SAMPLE_IDLE;
}
#endif
/* Reset update timer */
mi->last_stats_update = jiffies;
mi->sample_time = jiffies;
}
static bool
minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
struct ieee80211_tx_rate *rate)
{
int i;
if (rate->idx < 0)
return false;
if (!rate->count)
return false;
if (rate->flags & IEEE80211_TX_RC_MCS ||
rate->flags & IEEE80211_TX_RC_VHT_MCS)
return true;
for (i = 0; i < ARRAY_SIZE(mp->cck_rates); i++)
if (rate->idx == mp->cck_rates[i])
return true;
for (i = 0; i < ARRAY_SIZE(mp->ofdm_rates[0]); i++)
if (rate->idx == mp->ofdm_rates[mi->band][i])
return true;
return false;
}
static void
minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
{
int group, orig_group;
orig_group = group = MI_RATE_GROUP(*idx);
while (group > 0) {
group--;
if (!mi->supported[group])
continue;
if (minstrel_mcs_groups[group].streams >
minstrel_mcs_groups[orig_group].streams)
continue;
if (primary)
*idx = mi->groups[group].max_group_tp_rate[0];
else
*idx = mi->groups[group].max_group_tp_rate[1];
break;
}
}
static void
minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
u16 tid;
if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
return;
if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
return;
if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
return;
tid = ieee80211_get_tid(hdr);
if (likely(sta->ampdu_mlme.tid_tx[tid]))
return;
ieee80211_start_tx_ba_session(pubsta, tid, 0);
}
static void
minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
void *priv_sta, struct ieee80211_tx_status *st)
{
struct ieee80211_tx_info *info = st->info;
struct minstrel_ht_sta *mi = priv_sta;
struct ieee80211_tx_rate *ar = info->status.rates;
struct minstrel_rate_stats *rate, *rate2, *rate_sample = NULL;
struct minstrel_priv *mp = priv;
u32 update_interval = mp->update_interval;
bool last, update = false;
bool sample_status = false;
int i;
/* This packet was aggregated but doesn't carry status info */
if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
!(info->flags & IEEE80211_TX_STAT_AMPDU))
return;
if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
info->status.ampdu_ack_len =
(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
info->status.ampdu_len = 1;
}
/* wraparound */
if (mi->total_packets >= ~0 - info->status.ampdu_len) {
mi->total_packets = 0;
mi->sample_packets = 0;
}
mi->total_packets += info->status.ampdu_len;
if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
mi->sample_packets += info->status.ampdu_len;
mi->ampdu_packets++;
mi->ampdu_len += info->status.ampdu_len;
if (mi->sample_mode != MINSTREL_SAMPLE_IDLE)
rate_sample = minstrel_get_ratestats(mi, mi->sample_rate);
last = !minstrel_ht_txstat_valid(mp, mi, &ar[0]);
for (i = 0; !last; i++) {
last = (i == IEEE80211_TX_MAX_RATES - 1) ||
!minstrel_ht_txstat_valid(mp, mi, &ar[i + 1]);
rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
if (rate == rate_sample)
sample_status = true;
if (last)
rate->success += info->status.ampdu_ack_len;
rate->attempts += ar[i].count * info->status.ampdu_len;
}
switch (mi->sample_mode) {
case MINSTREL_SAMPLE_IDLE:
if (mp->hw->max_rates > 1 ||
mi->total_packets_cur < SAMPLE_SWITCH_THR)
update_interval /= 2;
break;
case MINSTREL_SAMPLE_ACTIVE:
if (!sample_status)
break;
mi->sample_mode = MINSTREL_SAMPLE_PENDING;
update = true;
break;
case MINSTREL_SAMPLE_PENDING:
if (sample_status)
break;
update = true;
minstrel_ht_update_stats(mp, mi, false);
break;
}
if (mp->hw->max_rates > 1) {
/*
* check for sudden death of spatial multiplexing,
* downgrade to a lower number of streams if necessary.
*/
rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
if (rate->attempts > 30 &&
rate->success < rate->attempts / 4) {
minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
update = true;
}
rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
if (rate2->attempts > 30 &&
rate2->success < rate2->attempts / 4) {
minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
update = true;
}
}
if (time_after(jiffies, mi->last_stats_update + update_interval)) {
update = true;
minstrel_ht_update_stats(mp, mi, true);
}
if (update)
minstrel_ht_update_rates(mp, mi);
}
static void
minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
int index)
{
struct minstrel_rate_stats *mrs;
unsigned int tx_time, tx_time_rtscts, tx_time_data;
unsigned int cw = mp->cw_min;
unsigned int ctime = 0;
unsigned int t_slot = 9; /* FIXME */
unsigned int ampdu_len = minstrel_ht_avg_ampdu_len(mi);
unsigned int overhead = 0, overhead_rtscts = 0;
mrs = minstrel_get_ratestats(mi, index);
if (mrs->prob_avg < MINSTREL_FRAC(1, 10)) {
mrs->retry_count = 1;
mrs->retry_count_rtscts = 1;
return;
}
mrs->retry_count = 2;
mrs->retry_count_rtscts = 2;
mrs->retry_updated = true;
tx_time_data = minstrel_get_duration(index) * ampdu_len / 1000;
/* Contention time for first 2 tries */
ctime = (t_slot * cw) >> 1;
cw = min((cw << 1) | 1, mp->cw_max);
ctime += (t_slot * cw) >> 1;
cw = min((cw << 1) | 1, mp->cw_max);
if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(index))) {
overhead = mi->overhead_legacy;
overhead_rtscts = mi->overhead_legacy_rtscts;
} else {
overhead = mi->overhead;
overhead_rtscts = mi->overhead_rtscts;
}
/* Total TX time for data and Contention after first 2 tries */
tx_time = ctime + 2 * (overhead + tx_time_data);
tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
/* See how many more tries we can fit inside segment size */
do {
/* Contention time for this try */
ctime = (t_slot * cw) >> 1;
cw = min((cw << 1) | 1, mp->cw_max);
/* Total TX time after this try */
tx_time += ctime + overhead + tx_time_data;
tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
if (tx_time_rtscts < mp->segment_size)
mrs->retry_count_rtscts++;
} while ((tx_time < mp->segment_size) &&
(++mrs->retry_count < mp->max_retry));
}
static void
minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
struct ieee80211_sta_rates *ratetbl, int offset, int index)
{
int group_idx = MI_RATE_GROUP(index);
const struct mcs_group *group = &minstrel_mcs_groups[group_idx];
struct minstrel_rate_stats *mrs;
u8 idx;
u16 flags = group->flags;
mrs = minstrel_get_ratestats(mi, index);
if (!mrs->retry_updated)
minstrel_calc_retransmit(mp, mi, index);
if (mrs->prob_avg < MINSTREL_FRAC(20, 100) || !mrs->retry_count) {
ratetbl->rate[offset].count = 2;
ratetbl->rate[offset].count_rts = 2;
ratetbl->rate[offset].count_cts = 2;
} else {
ratetbl->rate[offset].count = mrs->retry_count;
ratetbl->rate[offset].count_cts = mrs->retry_count;
ratetbl->rate[offset].count_rts = mrs->retry_count_rtscts;
}
index = MI_RATE_IDX(index);
if (group_idx == MINSTREL_CCK_GROUP)
idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
else if (group_idx == MINSTREL_OFDM_GROUP)
idx = mp->ofdm_rates[mi->band][index %
ARRAY_SIZE(mp->ofdm_rates[0])];
else if (flags & IEEE80211_TX_RC_VHT_MCS)
idx = ((group->streams - 1) << 4) |
(index & 0xF);
else
idx = index + (group->streams - 1) * 8;
/* enable RTS/CTS if needed:
* - if station is in dynamic SMPS (and streams > 1)
* - for fallback rates, to increase chances of getting through
*/
if (offset > 0 ||
(mi->sta->smps_mode == IEEE80211_SMPS_DYNAMIC &&
group->streams > 1)) {
ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
flags |= IEEE80211_TX_RC_USE_RTS_CTS;
}
ratetbl->rate[offset].idx = idx;
ratetbl->rate[offset].flags = flags;
}
static inline int
minstrel_ht_get_prob_avg(struct minstrel_ht_sta *mi, int rate)
{
int group = MI_RATE_GROUP(rate);
rate = MI_RATE_IDX(rate);
return mi->groups[group].rates[rate].prob_avg;
}
static int
minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
{
int group = MI_RATE_GROUP(mi->max_prob_rate);
const struct mcs_group *g = &minstrel_mcs_groups[group];
int rate = MI_RATE_IDX(mi->max_prob_rate);
unsigned int duration;
/* Disable A-MSDU if max_prob_rate is bad */
if (mi->groups[group].rates[rate].prob_avg < MINSTREL_FRAC(50, 100))
return 1;
duration = g->duration[rate];
duration <<= g->shift;
/* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
if (duration > MCS_DURATION(1, 0, 52))
return 500;
/*
* If the rate is slower than single-stream MCS4, limit A-MSDU to usual
* data packet size
*/
if (duration > MCS_DURATION(1, 0, 104))
return 1600;
/*
* If the rate is slower than single-stream MCS7, or if the max throughput
* rate success probability is less than 75%, limit A-MSDU to twice the usual
* data packet size
*/
if (duration > MCS_DURATION(1, 0, 260) ||
(minstrel_ht_get_prob_avg(mi, mi->max_tp_rate[0]) <
MINSTREL_FRAC(75, 100)))
return 3200;
/*
* HT A-MPDU limits maximum MPDU size under BA agreement to 4095 bytes.
* Since aggregation sessions are started/stopped without txq flush, use
* the limit here to avoid the complexity of having to de-aggregate
* packets in the queue.
*/
if (!mi->sta->vht_cap.vht_supported)
return IEEE80211_MAX_MPDU_LEN_HT_BA;
/* unlimited */
return 0;
}
static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
struct ieee80211_sta_rates *rates;
u16 first_rate = mi->max_tp_rate[0];
int i = 0;
if (mi->sample_mode == MINSTREL_SAMPLE_ACTIVE)
first_rate = mi->sample_rate;
rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
if (!rates)
return;
/* Start with max_tp_rate[0] */
minstrel_ht_set_rate(mp, mi, rates, i++, first_rate);
if (mp->hw->max_rates >= 3) {
/* At least 3 tx rates supported, use max_tp_rate[1] next */
minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[1]);
}
if (mp->hw->max_rates >= 2) {
minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
}
mi->sta->max_rc_amsdu_len = minstrel_ht_get_max_amsdu_len(mi);
rates->rate[i].idx = -1;
rate_control_set_rates(mp->hw, mi->sta, rates);
}
static u16
minstrel_ht_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
u8 seq;
if (mp->hw->max_rates > 1) {
seq = mi->sample_seq;
mi->sample_seq = (seq + 1) % ARRAY_SIZE(minstrel_sample_seq);
seq = minstrel_sample_seq[seq];
} else {
seq = MINSTREL_SAMPLE_TYPE_INC;
}
return __minstrel_ht_get_sample_rate(mi, seq);
}
static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
struct ieee80211_tx_rate_control *txrc)
{
const struct mcs_group *sample_group;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
struct ieee80211_tx_rate *rate = &info->status.rates[0];
struct minstrel_ht_sta *mi = priv_sta;
struct minstrel_priv *mp = priv;
u16 sample_idx;
if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
!minstrel_ht_is_legacy_group(MI_RATE_GROUP(mi->max_prob_rate)))
minstrel_aggr_check(sta, txrc->skb);
info->flags |= mi->tx_flags;
#ifdef CONFIG_MAC80211_DEBUGFS
if (mp->fixed_rate_idx != -1)
return;
#endif
/* Don't use EAPOL frames for sampling on non-mrr hw */
if (mp->hw->max_rates == 1 &&
(info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
return;
if (mp->hw->max_rates == 1 && mp->sample_switch &&
(mi->total_packets_cur >= SAMPLE_SWITCH_THR ||
mp->sample_switch == 1))
return;
if (time_is_before_jiffies(mi->sample_time))
return;
mi->sample_time = jiffies + MINSTREL_SAMPLE_INTERVAL;
sample_idx = minstrel_ht_get_sample_rate(mp, mi);
if (!sample_idx)
return;
sample_group = &minstrel_mcs_groups[MI_RATE_GROUP(sample_idx)];
sample_idx = MI_RATE_IDX(sample_idx);
if (sample_group == &minstrel_mcs_groups[MINSTREL_CCK_GROUP] &&
(sample_idx >= 4) != txrc->short_preamble)
return;
info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
rate->count = 1;
if (sample_group == &minstrel_mcs_groups[MINSTREL_CCK_GROUP]) {
int idx = sample_idx % ARRAY_SIZE(mp->cck_rates);
rate->idx = mp->cck_rates[idx];
} else if (sample_group == &minstrel_mcs_groups[MINSTREL_OFDM_GROUP]) {
int idx = sample_idx % ARRAY_SIZE(mp->ofdm_rates[0]);
rate->idx = mp->ofdm_rates[mi->band][idx];
} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
ieee80211_rate_set_vht(rate, MI_RATE_IDX(sample_idx),
sample_group->streams);
} else {
rate->idx = sample_idx + (sample_group->streams - 1) * 8;
}
rate->flags = sample_group->flags;
}
static void
minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
struct ieee80211_supported_band *sband,
struct ieee80211_sta *sta)
{
int i;
if (sband->band != NL80211_BAND_2GHZ)
return;
if (sta->ht_cap.ht_supported &&
!ieee80211_hw_check(mp->hw, SUPPORTS_HT_CCK_RATES))
return;
for (i = 0; i < 4; i++) {
if (mp->cck_rates[i] == 0xff ||
!rate_supported(sta, sband->band, mp->cck_rates[i]))
continue;
mi->supported[MINSTREL_CCK_GROUP] |= BIT(i);
if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
mi->supported[MINSTREL_CCK_GROUP] |= BIT(i + 4);
}
}
static void
minstrel_ht_update_ofdm(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
struct ieee80211_supported_band *sband,
struct ieee80211_sta *sta)
{
const u8 *rates;
int i;
if (sta->ht_cap.ht_supported)
return;
rates = mp->ofdm_rates[sband->band];
for (i = 0; i < ARRAY_SIZE(mp->ofdm_rates[0]); i++) {
if (rates[i] == 0xff ||
!rate_supported(sta, sband->band, rates[i]))
continue;
mi->supported[MINSTREL_OFDM_GROUP] |= BIT(i);
}
}
static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
struct cfg80211_chan_def *chandef,
struct ieee80211_sta *sta, void *priv_sta)
{
struct minstrel_priv *mp = priv;
struct minstrel_ht_sta *mi = priv_sta;
struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
u16 ht_cap = sta->ht_cap.cap;
struct ieee80211_sta_vht_cap *vht_cap = &sta->vht_cap;
const struct ieee80211_rate *ctl_rate;
bool ldpc, erp;
int use_vht;
int n_supported = 0;
int ack_dur;
int stbc;
int i;
BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != MINSTREL_GROUPS_NB);
if (vht_cap->vht_supported)
use_vht = vht_cap->vht_mcs.tx_mcs_map != cpu_to_le16(~0);
else
use_vht = 0;
memset(mi, 0, sizeof(*mi));
mi->sta = sta;
mi->band = sband->band;
mi->last_stats_update = jiffies;
ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0);
mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0);
mi->overhead += ack_dur;
mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
ctl_rate = &sband->bitrates[rate_lowest_index(sband, sta)];
erp = ctl_rate->flags & IEEE80211_RATE_ERP_G;
ack_dur = ieee80211_frame_duration(sband->band, 10,
ctl_rate->bitrate, erp, 1,
ieee80211_chandef_get_shift(chandef));
mi->overhead_legacy = ack_dur;
mi->overhead_legacy_rtscts = mi->overhead_legacy + 2 * ack_dur;
mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
if (!use_vht) {
stbc = (ht_cap & IEEE80211_HT_CAP_RX_STBC) >>
IEEE80211_HT_CAP_RX_STBC_SHIFT;
ldpc = ht_cap & IEEE80211_HT_CAP_LDPC_CODING;
} else {
stbc = (vht_cap->cap & IEEE80211_VHT_CAP_RXSTBC_MASK) >>
IEEE80211_VHT_CAP_RXSTBC_SHIFT;
ldpc = vht_cap->cap & IEEE80211_VHT_CAP_RXLDPC;
}
mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
if (ldpc)
mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
u32 gflags = minstrel_mcs_groups[i].flags;
int bw, nss;
mi->supported[i] = 0;
if (minstrel_ht_is_legacy_group(i))
continue;
if (gflags & IEEE80211_TX_RC_SHORT_GI) {
if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
if (!(ht_cap & IEEE80211_HT_CAP_SGI_40))
continue;
} else {
if (!(ht_cap & IEEE80211_HT_CAP_SGI_20))
continue;
}
}
if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
sta->bandwidth < IEEE80211_STA_RX_BW_40)
continue;
nss = minstrel_mcs_groups[i].streams;
/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
if (sta->smps_mode == IEEE80211_SMPS_STATIC && nss > 1)
continue;
/* HT rate */
if (gflags & IEEE80211_TX_RC_MCS) {
if (use_vht && minstrel_vht_only)
continue;
mi->supported[i] = mcs->rx_mask[nss - 1];
if (mi->supported[i])
n_supported++;
continue;
}
/* VHT rate */
if (!vht_cap->vht_supported ||
WARN_ON(!(gflags & IEEE80211_TX_RC_VHT_MCS)) ||
WARN_ON(gflags & IEEE80211_TX_RC_160_MHZ_WIDTH))
continue;
if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH) {
if (sta->bandwidth < IEEE80211_STA_RX_BW_80 ||
((gflags & IEEE80211_TX_RC_SHORT_GI) &&
!(vht_cap->cap & IEEE80211_VHT_CAP_SHORT_GI_80))) {
continue;
}
}
if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH)
bw = BW_40;
else if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH)
bw = BW_80;
else
bw = BW_20;
mi->supported[i] = minstrel_get_valid_vht_rates(bw, nss,
vht_cap->vht_mcs.tx_mcs_map);
if (mi->supported[i])
n_supported++;
}
minstrel_ht_update_cck(mp, mi, sband, sta);
minstrel_ht_update_ofdm(mp, mi, sband, sta);
/* create an initial rate table with the lowest supported rates */
minstrel_ht_update_stats(mp, mi, true);
minstrel_ht_update_rates(mp, mi);
}
static void
minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
struct cfg80211_chan_def *chandef,
struct ieee80211_sta *sta, void *priv_sta)
{
minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
}
static void
minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
struct cfg80211_chan_def *chandef,
struct ieee80211_sta *sta, void *priv_sta,
u32 changed)
{
minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
}
static void *
minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
{
struct ieee80211_supported_band *sband;
struct minstrel_ht_sta *mi;
struct minstrel_priv *mp = priv;
struct ieee80211_hw *hw = mp->hw;
int max_rates = 0;
int i;
for (i = 0; i < NUM_NL80211_BANDS; i++) {
sband = hw->wiphy->bands[i];
if (sband && sband->n_bitrates > max_rates)
max_rates = sband->n_bitrates;
}
return kzalloc(sizeof(*mi), gfp);
}
static void
minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
{
kfree(priv_sta);
}
static void
minstrel_ht_fill_rate_array(u8 *dest, struct ieee80211_supported_band *sband,
const s16 *bitrates, int n_rates, u32 rate_flags)
{
int i, j;
for (i = 0; i < sband->n_bitrates; i++) {
struct ieee80211_rate *rate = &sband->bitrates[i];
if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
continue;
for (j = 0; j < n_rates; j++) {
if (rate->bitrate != bitrates[j])
continue;
dest[j] = i;
break;
}
}
}
static void
minstrel_ht_init_cck_rates(struct minstrel_priv *mp)
{
static const s16 bitrates[4] = { 10, 20, 55, 110 };
struct ieee80211_supported_band *sband;
u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
memset(mp->cck_rates, 0xff, sizeof(mp->cck_rates));
sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
if (!sband)
return;
BUILD_BUG_ON(ARRAY_SIZE(mp->cck_rates) != ARRAY_SIZE(bitrates));
minstrel_ht_fill_rate_array(mp->cck_rates, sband,
minstrel_cck_bitrates,
ARRAY_SIZE(minstrel_cck_bitrates),
rate_flags);
}
static void
minstrel_ht_init_ofdm_rates(struct minstrel_priv *mp, enum nl80211_band band)
{
static const s16 bitrates[8] = { 60, 90, 120, 180, 240, 360, 480, 540 };
struct ieee80211_supported_band *sband;
u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
memset(mp->ofdm_rates[band], 0xff, sizeof(mp->ofdm_rates[band]));
sband = mp->hw->wiphy->bands[band];
if (!sband)
return;
BUILD_BUG_ON(ARRAY_SIZE(mp->ofdm_rates[band]) != ARRAY_SIZE(bitrates));
minstrel_ht_fill_rate_array(mp->ofdm_rates[band], sband,
minstrel_ofdm_bitrates,
ARRAY_SIZE(minstrel_ofdm_bitrates),
rate_flags);
}
static void *
minstrel_ht_alloc(struct ieee80211_hw *hw)
{
struct minstrel_priv *mp;
int i;
mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
if (!mp)
return NULL;
mp->sample_switch = -1;
/* contention window settings
* Just an approximation. Using the per-queue values would complicate
* the calculations and is probably unnecessary */
mp->cw_min = 15;
mp->cw_max = 1023;
/* maximum time that the hw is allowed to stay in one MRR segment */
mp->segment_size = 6000;
if (hw->max_rate_tries > 0)
mp->max_retry = hw->max_rate_tries;
else
/* safe default, does not necessarily have to match hw properties */
mp->max_retry = 7;
if (hw->max_rates >= 4)
mp->has_mrr = true;
mp->hw = hw;
mp->update_interval = HZ / 10;
minstrel_ht_init_cck_rates(mp);
for (i = 0; i < ARRAY_SIZE(mp->hw->wiphy->bands); i++)
minstrel_ht_init_ofdm_rates(mp, i);
return mp;
}
#ifdef CONFIG_MAC80211_DEBUGFS
static void minstrel_ht_add_debugfs(struct ieee80211_hw *hw, void *priv,
struct dentry *debugfsdir)
{
struct minstrel_priv *mp = priv;
mp->fixed_rate_idx = (u32) -1;
debugfs_create_u32("fixed_rate_idx", S_IRUGO | S_IWUGO, debugfsdir,
&mp->fixed_rate_idx);
debugfs_create_u32("sample_switch", S_IRUGO | S_IWUSR, debugfsdir,
&mp->sample_switch);
}
#endif
static void
minstrel_ht_free(void *priv)
{
kfree(priv);
}
static u32 minstrel_ht_get_expected_throughput(void *priv_sta)
{
struct minstrel_ht_sta *mi = priv_sta;
int i, j, prob, tp_avg;
i = MI_RATE_GROUP(mi->max_tp_rate[0]);
j = MI_RATE_IDX(mi->max_tp_rate[0]);
prob = mi->groups[i].rates[j].prob_avg;
/* convert tp_avg from pkt per second in kbps */
tp_avg = minstrel_ht_get_tp_avg(mi, i, j, prob) * 10;
tp_avg = tp_avg * AVG_PKT_SIZE * 8 / 1024;
return tp_avg;
}
static const struct rate_control_ops mac80211_minstrel_ht = {
.name = "minstrel_ht",
.tx_status_ext = minstrel_ht_tx_status,
.get_rate = minstrel_ht_get_rate,
.rate_init = minstrel_ht_rate_init,
.rate_update = minstrel_ht_rate_update,
.alloc_sta = minstrel_ht_alloc_sta,
.free_sta = minstrel_ht_free_sta,
.alloc = minstrel_ht_alloc,
.free = minstrel_ht_free,
#ifdef CONFIG_MAC80211_DEBUGFS
.add_debugfs = minstrel_ht_add_debugfs,
.add_sta_debugfs = minstrel_ht_add_sta_debugfs,
#endif
.get_expected_throughput = minstrel_ht_get_expected_throughput,
};
static void __init init_sample_table(void)
{
int col, i, new_idx;
u8 rnd[MCS_GROUP_RATES];
memset(sample_table, 0xff, sizeof(sample_table));
for (col = 0; col < SAMPLE_COLUMNS; col++) {
prandom_bytes(rnd, sizeof(rnd));
for (i = 0; i < MCS_GROUP_RATES; i++) {
new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
while (sample_table[col][new_idx] != 0xff)
new_idx = (new_idx + 1) % MCS_GROUP_RATES;
sample_table[col][new_idx] = i;
}
}
}
int __init
rc80211_minstrel_init(void)
{
init_sample_table();
return ieee80211_rate_control_register(&mac80211_minstrel_ht);
}
void
rc80211_minstrel_exit(void)
{
ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
}
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