wifi: mac80211: switch airtime fairness back to deficit round-robin scheduling

This reverts commits 6a789ba679d652587532cec2a0e0274fda172f3b and
2433647bc8d983a543e7d31b41ca2de1c7e2c198.

The virtual time scheduler code has a number of issues:
- queues slowed down by hardware/firmware powersave handling were not properly
  handled.
- on ath10k in push-pull mode, tx queues that the driver tries to pull from
  were starved, causing excessive latency
- delay between tx enqueue and reported airtime use were causing excessively
  bursty tx behavior

The bursty behavior may also be present on the round-robin scheduler, but there
it is much easier to fix without introducing additional regressions

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220625212411.36675-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 3 insertions, 8 deletions

diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 4e0b969891de..3e26ad3be800 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -135,25 +135,18 @@ enum ieee80211_agg_stop_reason {
 #define AIRTIME_USE_TX		BIT(0)
 #define AIRTIME_USE_RX		BIT(1)
 
-
 struct airtime_info {
 	u64 rx_airtime;
 	u64 tx_airtime;
-	u64 v_t;
-	u64 last_scheduled;
-	struct list_head list;
+	s64 deficit;
 	atomic_t aql_tx_pending; /* Estimated airtime for frames pending */
 	u32 aql_limit_low;
 	u32 aql_limit_high;
-	u32 weight_reciprocal;
-	u16 weight;
 };
 
 void ieee80211_sta_update_pending_airtime(struct ieee80211_local *local,
 					  struct sta_info *sta, u8 ac,
 					  u16 tx_airtime, bool tx_completed);
-void ieee80211_register_airtime(struct ieee80211_txq *txq,
-				u32 tx_airtime, u32 rx_airtime);
 
 struct sta_info;
 
@@ -609,6 +602,7 @@ struct link_sta_info {
  * @tid_seq: per-TID sequence numbers for sending to this STA
  * @airtime: per-AC struct airtime_info describing airtime statistics for this
  *	station
+ * @airtime_weight: station weight for airtime fairness calculation purposes
  * @ampdu_mlme: A-MPDU state machine state
  * @mesh: mesh STA information
  * @debugfs_dir: debug filesystem directory dentry
@@ -693,6 +687,7 @@ struct sta_info {
 	u16 tid_seq[IEEE80211_QOS_CTL_TID_MASK + 1];
 
 	struct airtime_info airtime[IEEE80211_NUM_ACS];
+	u16 airtime_weight;
 
 	/*
 	 * Aggregation information, locked with lock.