package/kernel/mac80211/patches/335-mac80211-minstrel_ht-set-A-MSDU-tx-limits-based-on-s.patch

   1 From: Felix Fietkau <nbd@openwrt.org>
   2 Date: Thu, 18 Feb 2016 19:30:05 +0100
   3 Subject: [PATCH] mac80211: minstrel_ht: set A-MSDU tx limits based on selected
   4  max_prob_rate
   5
   6 Prevents excessive A-MSDU aggregation at low data rates or bad
   7 conditions.
   8
   9 Signed-off-by: Felix Fietkau <nbd@openwrt.org>
  10 ---
  11
  12 --- a/net/mac80211/rc80211_minstrel_ht.c
  13 +++ b/net/mac80211/rc80211_minstrel_ht.c
  14 @@ -883,6 +883,39 @@ minstrel_ht_set_rate(struct minstrel_pri
  15         ratetbl->rate[offset].flags = flags;
  16  }
  17
  18 +static int
  19 +minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
  20 +{
  21 +       int group = mi->max_prob_rate / MCS_GROUP_RATES;
  22 +       const struct mcs_group *g = &minstrel_mcs_groups[group];
  23 +       int rate = mi->max_prob_rate % MCS_GROUP_RATES;
  24 +
  25 +       /* Disable A-MSDU if max_prob_rate is bad */
  26 +       if (mi->groups[group].rates[rate].prob_ewma < MINSTREL_FRAC(50, 100))
  27 +               return 1;
  28 +
  29 +       /* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
  30 +       if (g->duration[rate] > MCS_DURATION(1, 0, 52))
  31 +               return 500;
  32 +
  33 +       /*
  34 +        * If the rate is slower than single-stream MCS4, limit A-MSDU to usual
  35 +        * data packet size
  36 +        */
  37 +       if (g->duration[rate] > MCS_DURATION(1, 0, 104))
  38 +               return 1500;
  39 +
  40 +       /*
  41 +        * If the rate is slower than single-stream MCS7, limit A-MSDU to twice
  42 +        * the usual data packet size
  43 +        */
  44 +       if (g->duration[rate] > MCS_DURATION(1, 0, 260))
  45 +               return 3000;
  46 +
  47 +       /* unlimited */
  48 +       return 0;
  49 +}
  50 +
  51  static void
  52  minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
  53  {
  54 @@ -907,6 +940,7 @@ minstrel_ht_update_rates(struct minstrel
  55                 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
  56         }
  57
  58 +       mi->sta->max_rc_amsdu_len = minstrel_ht_get_max_amsdu_len(mi);
  59         rates->rate[i].idx = -1;
  60         rate_control_set_rates(mp->hw, mi->sta, rates);
  61  }