mac80211: minstrel_ht: remove sample rate switching code for constrained 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>

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index e29d964..2f44f49 100644 (file)
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -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)
 {
@@ -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;
@@ -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,
@@ -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
 
@@ -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 */
@@ -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,
@@ -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)
@@ -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 */
@@ -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;
 
@@ -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);
 }
 
@@ -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 */
@@ -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++)
@@ -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
 

diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index 0d8c15f..06e7126 100644 (file)
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -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;
@@ -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];
@@ -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];