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mac80211: minstrel_ht: remove sample rate switching code for constrai…
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…ned devices

This was added to mitigate the effects of too much sampling on devices that
use a static global fallback table instead of configurable multi-rate retry.
Now that the sampling algorithm is improved, this code path no longer performs
any better than the standard probing on affected devices.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210127055735.78599-6-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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Felix Fietkau authored and Johannes Berg committed Feb 12, 2021
1 parent 4a8d0c9 commit c0eb09a
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Showing 2 changed files with 9 additions and 103 deletions.
95 changes: 6 additions & 89 deletions net/mac80211/rc80211_minstrel_ht.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -648,27 +648,6 @@ __minstrel_ht_get_sample_rate(struct minstrel_ht_sta *mi,
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)
{
Expand Down Expand Up @@ -1012,8 +991,7 @@ minstrel_ht_refill_sample_rates(struct minstrel_ht_sta *mi)
* 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)
minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
struct minstrel_mcs_group_data *mg;
struct minstrel_rate_stats *mrs;
Expand All @@ -1023,18 +1001,6 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
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,
Expand Down Expand Up @@ -1148,16 +1114,12 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
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

Expand Down Expand Up @@ -1247,11 +1209,10 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
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_rate_stats *rate, *rate2;
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 */
Expand All @@ -1278,49 +1239,18 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
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,
Expand All @@ -1343,7 +1273,7 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,

if (time_after(jiffies, mi->last_stats_update + update_interval)) {
update = true;
minstrel_ht_update_stats(mp, mi, true);
minstrel_ht_update_stats(mp, mi);
}

if (update)
Expand Down Expand Up @@ -1522,18 +1452,14 @@ 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);
minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);

if (mp->hw->max_rates >= 3) {
/* At least 3 tx rates supported, use max_tp_rate[1] next */
Expand Down Expand Up @@ -1592,11 +1518,6 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
(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;

Expand Down Expand Up @@ -1810,7 +1731,7 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
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_stats(mp, mi);
minstrel_ht_update_rates(mp, mi);
}

Expand Down Expand Up @@ -1926,8 +1847,6 @@ minstrel_ht_alloc(struct ieee80211_hw *hw)
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 */
Expand All @@ -1947,7 +1866,7 @@ minstrel_ht_alloc(struct ieee80211_hw *hw)
mp->has_mrr = true;

mp->hw = hw;
mp->update_interval = HZ / 10;
mp->update_interval = HZ / 20;

minstrel_ht_init_cck_rates(mp);
for (i = 0; i < ARRAY_SIZE(mp->hw->wiphy->bands); i++)
Expand All @@ -1965,8 +1884,6 @@ static void minstrel_ht_add_debugfs(struct ieee80211_hw *hw, void *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

Expand Down
17 changes: 3 additions & 14 deletions net/mac80211/rc80211_minstrel_ht.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,6 @@
struct minstrel_priv {
struct ieee80211_hw *hw;
bool has_mrr;
u32 sample_switch;
unsigned int cw_min;
unsigned int cw_max;
unsigned int max_retry;
Expand Down Expand Up @@ -147,12 +146,6 @@ struct minstrel_mcs_group_data {
struct minstrel_rate_stats rates[MCS_GROUP_RATES];
};

enum minstrel_sample_mode {
MINSTREL_SAMPLE_IDLE,
MINSTREL_SAMPLE_ACTIVE,
MINSTREL_SAMPLE_PENDING,
};

struct minstrel_sample_category {
u8 sample_group;
u16 sample_rates[MINSTREL_SAMPLE_RATES];
Expand Down Expand Up @@ -182,23 +175,19 @@ struct minstrel_ht_sta {
unsigned int overhead_legacy;
unsigned int overhead_legacy_rtscts;

unsigned int total_packets_last;
unsigned int total_packets_cur;
unsigned int total_packets;
unsigned int sample_packets;

/* tx flags to add for frames for this sta */
u32 tx_flags;

unsigned long sample_time;
struct minstrel_sample_category sample[__MINSTREL_SAMPLE_TYPE_MAX];
u8 band;

u8 sample_seq;

enum minstrel_sample_mode sample_mode;
u16 sample_rate;

u8 band;
unsigned long sample_time;
struct minstrel_sample_category sample[__MINSTREL_SAMPLE_TYPE_MAX];

/* Bitfield of supported MCS rates of all groups */
u16 supported[MINSTREL_GROUPS_NB];
Expand Down

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