mac80211/minstrel_ht: increase sampling frequency of some slower rates

If a rate is below the max_tp_rate, sample it frequently if:
- it is above max_tp_rate2, or
- it is above max_prob_rate and is a candidate for max_prob_rate
  (has fewer streams than max_tp_rate).
This helps the retry chain recover more quickly from bad statistics
caused by collisions or interference, and slightly reduces throughput
fluctuations with higher rates.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
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 4d35bc5..1b69924 100644 (file)
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -246,7 +246,6 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
        struct minstrel_rate_stats *mr;
        int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
        int group, i, index;
-       int prob_max_streams = 1;
 
        if (mi->ampdu_packets > 0) {
                mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
@@ -330,7 +329,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
                        cur_tp2 = cur_tp;
                        mi->max_tp_rate = mg->max_tp_rate;
                        cur_tp = mr->cur_tp;
-                       prob_max_streams = minstrel_mcs_groups[group].streams - 1;
+                       mi->max_prob_streams = minstrel_mcs_groups[group].streams - 1;
                }
 
                mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
@@ -340,8 +339,8 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
                }
        }
 
-       if (prob_max_streams < 1)
-               prob_max_streams = 1;
+       if (mi->max_prob_streams < 1)
+               mi->max_prob_streams = 1;
 
        for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
                mg = &mi->groups[group];
@@ -349,7 +348,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
                        continue;
                mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
                if (cur_prob_tp < mr->cur_tp &&
-                   minstrel_mcs_groups[group].streams <= prob_max_streams) {
+                   minstrel_mcs_groups[group].streams <= mi->max_prob_streams) {
                        mi->max_prob_rate = mg->max_prob_rate;
                        cur_prob = mr->cur_prob;
                        cur_prob_tp = mr->cur_tp;
@@ -630,6 +629,7 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 {
        struct minstrel_rate_stats *mr;
        struct minstrel_mcs_group_data *mg;
+       unsigned int sample_dur, sample_group;
        int sample_idx = 0;
 
        if (mi->sample_wait > 0) {
@@ -644,7 +644,8 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
        mg = &mi->groups[mi->sample_group];
        sample_idx = sample_table[mg->column][mg->index];
        mr = &mg->rates[sample_idx];
-       sample_idx += mi->sample_group * MCS_GROUP_RATES;
+       sample_group = mi->sample_group;
+       sample_idx += sample_group * MCS_GROUP_RATES;
        minstrel_next_sample_idx(mi);
 
        /*
@@ -665,8 +666,11 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
         * Make sure that lower rates get sampled only occasionally,
         * if the link is working perfectly.
         */
-       if (minstrel_get_duration(sample_idx) >
-           minstrel_get_duration(mi->max_tp_rate)) {
+       sample_dur = minstrel_get_duration(sample_idx);
+       if (sample_dur >= minstrel_get_duration(mi->max_tp_rate2) &&
+           (mi->max_prob_streams <
+            minstrel_mcs_groups[sample_group].streams ||
+            sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
                if (mr->sample_skipped < 20)
                        return -1;
 

diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index 302dbd5..c6d6a0d 100644 (file)
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -85,6 +85,7 @@ struct minstrel_ht_sta {
 
        /* best probability rate */
        unsigned int max_prob_rate;
+       unsigned int max_prob_streams;
 
        /* time of last status update */
        unsigned long stats_update;