package/kernel/mac80211/patches/subsys/377-mac80211-minstrel-do-not-sample-rates-3-times-slower.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Sat, 3 Mar 2018 18:48:58 +0100
   3 Subject: [PATCH] mac80211: minstrel: do not sample rates 3 times slower than
   4  max_prob_rate
   5
   6 These rates are highly unlikely to be used quickly, even if the link
   7 deteriorates rapidly. This improves throughput in cases where CCK rates
   8 are not reliable enough to be skipped entirely during sampling.
   9 Sampling these rates regularly can cost a lot of airtime.
  10
  11 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  12 ---
  13
  14 --- a/net/mac80211/rc80211_minstrel_ht.c
  15 +++ b/net/mac80211/rc80211_minstrel_ht.c
  16 @@ -1004,10 +1004,13 @@ minstrel_get_sample_rate(struct minstrel
  17                 return -1;
  18
  19         /*
  20 -        * Do not sample if the probability is already higher than 95%
  21 -        * to avoid wasting airtime.
  22 +        * Do not sample if the probability is already higher than 95%,
  23 +        * or if the rate is 3 times slower than the current max probability
  24 +        * rate, to avoid wasting airtime.
  25          */
  26 -       if (mrs->prob_ewma > MINSTREL_FRAC(95, 100))
  27 +       sample_dur = minstrel_get_duration(sample_idx);
  28 +       if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
  29 +           minstrel_get_duration(mi->max_prob_rate) * 3 < sample_dur)
  30                 return -1;
  31
  32         /*
  33 @@ -1017,7 +1020,6 @@ minstrel_get_sample_rate(struct minstrel
  34
  35         cur_max_tp_streams = minstrel_mcs_groups[tp_rate1 /
  36                 MCS_GROUP_RATES].streams;
  37 -       sample_dur = minstrel_get_duration(sample_idx);
  38         if (sample_dur >= minstrel_get_duration(tp_rate2) &&
  39             (cur_max_tp_streams - 1 <
  40              minstrel_mcs_groups[sample_group].streams ||