git.openwrt.org Git - openwrt/staging/chunkeey.git/blob

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Wed, 12 Aug 2020 17:07:10 +0200
   3 Subject: [PATCH] mac80211: improve AQL aggregation estimation for low data
   4  rates
   5
   6 Links with low data rates use much smaller aggregates and are much more
   7 sensitive to latency added by bufferbloat.
   8 Tune the assumed aggregation length based on the tx rate duration.
   9
  10 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  11 ---
  12
  13 --- a/net/mac80211/airtime.c
  14 +++ b/net/mac80211/airtime.c
  15 @@ -646,27 +646,40 @@ u32 ieee80211_calc_expected_tx_airtime(s
  16         if (pubsta) {
  17                 struct sta_info *sta = container_of(pubsta, struct sta_info,
  18                                                     sta);
  19 +               struct ieee80211_rx_status stat;
  20                 struct ieee80211_tx_rate *rate = &sta->tx_stats.last_rate;
  21                 struct rate_info *ri = &sta->tx_stats.last_rate_info;
  22 -               u32 airtime;
  23 +               u32 duration, overhead;
  24 +               u8 agg_shift;
  25
  26 -               if (!(rate->flags & (IEEE80211_TX_RC_VHT_MCS |
  27 -                                    IEEE80211_TX_RC_MCS)))
  28 -                       ampdu = false;
  29 +               ieee80211_fill_rx_status(&stat, hw, rate, ri, band, len);
  30 +
  31 +               if (stat.encoding == RX_ENC_LEGACY || !ampdu)
  32 +                       return ieee80211_calc_rx_airtime(hw, &stat, len);
  33
  34 +               duration = ieee80211_get_rate_duration(hw, &stat, &overhead);
  35                 /*
  36                  * Assume that HT/VHT transmission on any AC except VO will
  37                  * use aggregation. Since we don't have reliable reporting
  38 -                * of aggregation length, assume an average of 16.
  39 +                * of aggregation length, assume an average size based on the
  40 +                * tx rate.
  41                  * This will not be very accurate, but much better than simply
  42 -                * assuming un-aggregated tx.
  43 +                * assuming un-aggregated tx in all cases.
  44                  */
  45 -               airtime = ieee80211_calc_tx_airtime_rate(hw, rate, ri, band,
  46 -                                                        ampdu ? len * 16 : len);
  47 -               if (ampdu)
  48 -                       airtime /= 16;
  49 +               if (duration > 400) /* <= VHT20 MCS2 1S */
  50 +                       agg_shift = 1;
  51 +               else if (duration > 250) /* <= VHT20 MCS3 1S or MCS1 2S */
  52 +                       agg_shift = 2;
  53 +               else if (duration > 150) /* <= VHT20 MCS5 1S or MCS3 2S */
  54 +                       agg_shift = 3;
  55 +               else
  56 +                       agg_shift = 4;
  57
  58 -               return airtime;
  59 +               duration *= len;
  60 +               duration /= AVG_PKT_SIZE;
  61 +               duration /= 1024;
  62 +
  63 +               return duration + (overhead >> agg_shift);
  64         }
  65
  66         if (!conf)