package/kernel/mac80211/patches/340-mac80211-minstrel-store-probability-variance-instead.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Wed, 14 Dec 2016 20:17:06 +0100
   3 Subject: [PATCH] mac80211: minstrel: store probability variance instead of
   4  standard deviation
   5
   6 This avoids the costly int_sqrt calls in the statistics update and moves
   7 it to the debugfs code instead.
   8 This also fixes an overflow in the previous standard deviation
   9 calculation.
  10
  11 Signed-off-by: Thomas Huehn <thomas.huehn@evernet-eg.de>
  12 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  13 ---
  14
  15 --- a/net/mac80211/rc80211_minstrel.c
  16 +++ b/net/mac80211/rc80211_minstrel.c
  17 @@ -168,10 +168,10 @@ minstrel_calc_rate_stats(struct minstrel
  18                         mrs->prob_ewma = cur_prob;
  19                 } else {
  20                         /* update exponential weighted moving variance */
  21 -                       mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd,
  22 -                                                        cur_prob,
  23 -                                                        mrs->prob_ewma,
  24 -                                                        EWMA_LEVEL);
  25 +                       mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
  26 +                                                       cur_prob,
  27 +                                                       mrs->prob_ewma,
  28 +                                                       EWMA_LEVEL);
  29
  30                         /*update exponential weighted moving avarage */
  31                         mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
  32 --- a/net/mac80211/rc80211_minstrel.h
  33 +++ b/net/mac80211/rc80211_minstrel.h
  34 @@ -36,21 +36,16 @@ minstrel_ewma(int old, int new, int weig
  35  }
  36
  37  /*
  38 - * Perform EWMSD (Exponentially Weighted Moving Standard Deviation) calculation
  39 + * Perform EWMV (Exponentially Weighted Moving Variance) calculation
  40   */
  41  static inline int
  42 -minstrel_ewmsd(int old_ewmsd, int cur_prob, int prob_ewma, int weight)
  43 +minstrel_ewmv(int old_ewmv, int cur_prob, int prob_ewma, int weight)
  44  {
  45 -       int diff, incr, tmp_var;
  46 +       int diff, incr;
  47
  48 -       /* calculate exponential weighted moving variance */
  49 -       diff = MINSTREL_TRUNC((cur_prob - prob_ewma) * 1000000);
  50 +       diff = cur_prob - prob_ewma;
  51         incr = (EWMA_DIV - weight) * diff / EWMA_DIV;
  52 -       tmp_var = old_ewmsd * old_ewmsd;
  53 -       tmp_var = weight * (tmp_var + diff * incr / 1000000) / EWMA_DIV;
  54 -
  55 -       /* return standard deviation */
  56 -       return (u16) int_sqrt(tmp_var);
  57 +       return weight * (old_ewmv + MINSTREL_TRUNC(diff * incr)) / EWMA_DIV;
  58  }
  59
  60  struct minstrel_rate_stats {
  61 @@ -65,7 +60,7 @@ struct minstrel_rate_stats {
  62          *  prob_ewma - exponential weighted moving average of prob
  63          *  prob_ewmsd - exp. weighted moving standard deviation of prob */
  64         unsigned int prob_ewma;
  65 -       u16 prob_ewmsd;
  66 +       u16 prob_ewmv;
  67
  68         /* maximum retry counts */
  69         u8 retry_count;
  70 @@ -151,6 +146,14 @@ struct minstrel_debugfs_info {
  71         char buf[];
  72  };
  73
  74 +/* Get EWMSD (Exponentially Weighted Moving Standard Deviation) * 10 */
  75 +static inline int
  76 +minstrel_get_ewmsd10(struct minstrel_rate_stats *mrs)
  77 +{
  78 +       unsigned int ewmv = mrs->prob_ewmv;
  79 +       return int_sqrt(MINSTREL_TRUNC(ewmv * 1000 * 1000));
  80 +}
  81 +
  82  extern const struct rate_control_ops mac80211_minstrel;
  83  void minstrel_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
  84  void minstrel_remove_sta_debugfs(void *priv, void *priv_sta);
  85 --- a/net/mac80211/rc80211_minstrel_debugfs.c
  86 +++ b/net/mac80211/rc80211_minstrel_debugfs.c
  87 @@ -93,6 +93,7 @@ minstrel_stats_open(struct inode *inode,
  88         for (i = 0; i < mi->n_rates; i++) {
  89                 struct minstrel_rate *mr = &mi->r[i];
  90                 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
  91 +               unsigned int prob_ewmsd;
  92
  93                 *(p++) = (i == mi->max_tp_rate[0]) ? 'A' : ' ';
  94                 *(p++) = (i == mi->max_tp_rate[1]) ? 'B' : ' ';
  95 @@ -108,6 +109,7 @@ minstrel_stats_open(struct inode *inode,
  96                 tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
  97                 tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
  98                 eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
  99 +               prob_ewmsd = minstrel_get_ewmsd10(mrs);
 100
 101                 p += sprintf(p, "%4u.%1u    %4u.%1u     %3u.%1u    %3u.%1u"
 102                                 "     %3u   %3u %-3u   "
 103 @@ -115,7 +117,7 @@ minstrel_stats_open(struct inode *inode,
 104                                 tp_max / 10, tp_max % 10,
 105                                 tp_avg / 10, tp_avg % 10,
 106                                 eprob / 10, eprob % 10,
 107 -                               mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
 108 +                               prob_ewmsd / 10, prob_ewmsd % 10,
 109                                 mrs->retry_count,
 110                                 mrs->last_success,
 111                                 mrs->last_attempts,
 112 @@ -159,6 +161,7 @@ minstrel_stats_csv_open(struct inode *in
 113         for (i = 0; i < mi->n_rates; i++) {
 114                 struct minstrel_rate *mr = &mi->r[i];
 115                 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
 116 +               unsigned int prob_ewmsd;
 117
 118                 p += sprintf(p, "%s" ,((i == mi->max_tp_rate[0]) ? "A" : ""));
 119                 p += sprintf(p, "%s" ,((i == mi->max_tp_rate[1]) ? "B" : ""));
 120 @@ -174,13 +177,14 @@ minstrel_stats_csv_open(struct inode *in
 121                 tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
 122                 tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
 123                 eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
 124 +               prob_ewmsd = minstrel_get_ewmsd10(mrs);
 125
 126                 p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"
 127                                 "%llu,%llu,%d,%d\n",
 128                                 tp_max / 10, tp_max % 10,
 129                                 tp_avg / 10, tp_avg % 10,
 130                                 eprob / 10, eprob % 10,
 131 -                               mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
 132 +                               prob_ewmsd / 10, prob_ewmsd % 10,
 133                                 mrs->retry_count,
 134                                 mrs->last_success,
 135                                 mrs->last_attempts,
 136 --- a/net/mac80211/rc80211_minstrel_ht_debugfs.c
 137 +++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
 138 @@ -41,6 +41,7 @@ minstrel_ht_stats_dump(struct minstrel_h
 139                 struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
 140                 static const int bitrates[4] = { 10, 20, 55, 110 };
 141                 int idx = i * MCS_GROUP_RATES + j;
 142 +               unsigned int prob_ewmsd;
 143
 144                 if (!(mi->supported[i] & BIT(j)))
 145                         continue;
 146 @@ -84,6 +85,7 @@ minstrel_ht_stats_dump(struct minstrel_h
 147                 tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
 148                 tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_ewma);
 149                 eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
 150 +               prob_ewmsd = minstrel_get_ewmsd10(mrs);
 151
 152                 p += sprintf(p, "%4u.%1u    %4u.%1u     %3u.%1u    %3u.%1u"
 153                                 "     %3u   %3u %-3u   "
 154 @@ -91,7 +93,7 @@ minstrel_ht_stats_dump(struct minstrel_h
 155                                 tp_max / 10, tp_max % 10,
 156                                 tp_avg / 10, tp_avg % 10,
 157                                 eprob / 10, eprob % 10,
 158 -                               mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
 159 +                               prob_ewmsd / 10, prob_ewmsd % 10,
 160                                 mrs->retry_count,
 161                                 mrs->last_success,
 162                                 mrs->last_attempts,
 163 @@ -185,6 +187,7 @@ minstrel_ht_stats_csv_dump(struct minstr
 164                 struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
 165                 static const int bitrates[4] = { 10, 20, 55, 110 };
 166                 int idx = i * MCS_GROUP_RATES + j;
 167 +               unsigned int prob_ewmsd;
 168
 169                 if (!(mi->supported[i] & BIT(j)))
 170                         continue;
 171 @@ -225,13 +228,14 @@ minstrel_ht_stats_csv_dump(struct minstr
 172                 tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
 173                 tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_ewma);
 174                 eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
 175 +               prob_ewmsd = minstrel_get_ewmsd10(mrs);
 176
 177                 p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,"
 178                                 "%u,%llu,%llu,",
 179                                 tp_max / 10, tp_max % 10,
 180                                 tp_avg / 10, tp_avg % 10,
 181                                 eprob / 10, eprob % 10,
 182 -                               mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
 183 +                               prob_ewmsd / 10, prob_ewmsd % 10,
 184                                 mrs->retry_count,
 185                                 mrs->last_success,
 186                                 mrs->last_attempts,