package/kernel/mac80211/patches/subsys/311-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Tue, 14 Dec 2021 17:53:12 +0100
   3 Subject: [PATCH] mac80211: use coarse boottime for airtime fairness code
   4
   5 The time values used by the airtime fairness code only need to be accurate
   6 enough to cover station activity detection.
   7 Using ktime_get_coarse_boottime_ns instead of ktime_get_boottime_ns will
   8 drop the accuracy down to jiffies intervals, but at the same time saves
   9 a lot of CPU cycles in a hot path
  10
  11 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  12 ---
  13
  14 --- a/net/mac80211/tx.c
  15 +++ b/net/mac80211/tx.c
  16 @@ -3827,7 +3827,7 @@ struct ieee80211_txq *ieee80211_next_txq
  17  {
  18         struct ieee80211_local *local = hw_to_local(hw);
  19         struct airtime_sched_info *air_sched;
  20 -       u64 now = ktime_get_boottime_ns();
  21 +       u64 now = ktime_get_coarse_boottime_ns();
  22         struct ieee80211_txq *ret = NULL;
  23         struct airtime_info *air_info;
  24         struct txq_info *txqi = NULL;
  25 @@ -3954,7 +3954,7 @@ void ieee80211_update_airtime_weight(str
  26         u64 weight_sum = 0;
  27
  28         if (unlikely(!now))
  29 -               now = ktime_get_boottime_ns();
  30 +               now = ktime_get_coarse_boottime_ns();
  31
  32         lockdep_assert_held(&air_sched->lock);
  33
  34 @@ -3980,7 +3980,7 @@ void ieee80211_schedule_txq(struct ieee8
  35         struct ieee80211_local *local = hw_to_local(hw);
  36         struct txq_info *txqi = to_txq_info(txq);
  37         struct airtime_sched_info *air_sched;
  38 -       u64 now = ktime_get_boottime_ns();
  39 +       u64 now = ktime_get_coarse_boottime_ns();
  40         struct airtime_info *air_info;
  41         u8 ac = txq->ac;
  42         bool was_active;
  43 @@ -4038,7 +4038,7 @@ static void __ieee80211_unschedule_txq(s
  44
  45         if (!purge)
  46                 airtime_set_active(air_sched, air_info,
  47 -                                  ktime_get_boottime_ns());
  48 +                                  ktime_get_coarse_boottime_ns());
  49
  50         rb_erase_cached(&txqi->schedule_order,
  51                         &air_sched->active_txqs);
  52 @@ -4126,7 +4126,7 @@ bool ieee80211_txq_may_transmit(struct i
  53         if (RB_EMPTY_NODE(&txqi->schedule_order))
  54                 goto out;
  55
  56 -       now = ktime_get_boottime_ns();
  57 +       now = ktime_get_coarse_boottime_ns();
  58
  59         /* Like in ieee80211_next_txq(), make sure the first station in the
  60          * scheduling order is eligible for transmission to avoid starvation.