package/mac80211/patches/426-minstrel_performance.patch

   1 This patch enhances minstrel's performance for non-MRR setups,
   2 by preventing it from sampling slower rates with >95% success
   3 probability and by putting at least 1 non-sample frame between
   4 several sample frames.
   5
   6 Signed-off-by: Felix Fietkau <nbd@openwrt.org>
   7
   8 --- a/net/mac80211/rc80211_minstrel.c
   9 +++ b/net/mac80211/rc80211_minstrel.c
  10 @@ -126,7 +126,9 @@ minstrel_update_stats(struct minstrel_pr
  11                         mr->adjusted_retry_count = mr->retry_count >> 1;
  12                         if (mr->adjusted_retry_count > 2)
  13                                 mr->adjusted_retry_count = 2;
  14 +                       mr->sample_limit = 4;
  15                 } else {
  16 +                       mr->sample_limit = -1;
  17                         mr->adjusted_retry_count = mr->retry_count;
  18                 }
  19                 if (!mr->adjusted_retry_count)
  20 @@ -265,7 +267,8 @@ minstrel_get_rate(void *priv, struct iee
  21                         (mi->sample_count + mi->sample_deferred / 2);
  22
  23         /* delta > 0: sampling required */
  24 -       if (delta > 0) {
  25 +       if ((delta > 0) && (mrr || !mi->prev_sample)) {
  26 +               struct minstrel_rate *msr;
  27                 if (mi->packet_count >= 10000) {
  28                         mi->sample_deferred = 0;
  29                         mi->sample_count = 0;
  30 @@ -284,13 +287,20 @@ minstrel_get_rate(void *priv, struct iee
  31                 }
  32
  33                 sample_ndx = minstrel_get_next_sample(mi);
  34 +               msr = &mi->r[sample_ndx];
  35                 sample = true;
  36 -               sample_slower = mrr && (mi->r[sample_ndx].perfect_tx_time >
  37 +               sample_slower = mrr && (msr->perfect_tx_time >
  38                         mi->r[ndx].perfect_tx_time);
  39
  40                 if (!sample_slower) {
  41 -                       ndx = sample_ndx;
  42 -                       mi->sample_count++;
  43 +                       if (msr->sample_limit != 0) {
  44 +                               ndx = sample_ndx;
  45 +                               mi->sample_count++;
  46 +                               if (msr->sample_limit > 0)
  47 +                                       msr->sample_limit--;
  48 +                       } else {
  49 +                               sample = false;
  50 +                       }
  51                 } else {
  52                         /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
  53                          * packets that have the sampling rate deferred to the
  54 @@ -302,10 +312,20 @@ minstrel_get_rate(void *priv, struct iee
  55                         mi->sample_deferred++;
  56                 }
  57         }
  58 +       mi->prev_sample = sample;
  59 +
  60 +       /* If we're not using MRR and the sampling rate already
  61 +        * has a probability of >95%, we shouldn't be attempting
  62 +        * to use it, as this only wastes precious airtime */
  63 +       if (!mrr && sample && (mi->r[ndx].probability > 17100))
  64 +               ndx = mi->max_tp_rate;
  65 +
  66         ar[0].idx = mi->r[ndx].rix;
  67         ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);
  68
  69         if (!mrr) {
  70 +               if (!sample)
  71 +                       ar[0].count = mp->max_retry;
  72                 ar[1].idx = mi->lowest_rix;
  73                 ar[1].count = mp->max_retry;
  74                 return;
  75 @@ -401,6 +421,7 @@ minstrel_rate_init(void *priv, struct ie
  76
  77                 /* calculate maximum number of retransmissions before
  78                  * fallback (based on maximum segment size) */
  79 +               mr->sample_limit = -1;
  80                 mr->retry_count = 1;
  81                 mr->retry_count_cts = 1;
  82                 mr->retry_count_rtscts = 1;
  83 --- a/net/mac80211/rc80211_minstrel.h
  84 +++ b/net/mac80211/rc80211_minstrel.h
  85 @@ -16,6 +16,7 @@ struct minstrel_rate {
  86         unsigned int perfect_tx_time;
  87         unsigned int ack_time;
  88
  89 +       int sample_limit;
  90         unsigned int retry_count;
  91         unsigned int retry_count_cts;
  92         unsigned int retry_count_rtscts;
  93 @@ -57,6 +58,7 @@ struct minstrel_sta_info {
  94
  95         int n_rates;
  96         struct minstrel_rate *r;
  97 +       bool prev_sample;
  98
  99         /* sampling table */
 100         u8 *sample_table;