mac80211: increase airtime scheduler quantum

improves performance by requiring fewer iterations over tx queues

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/package/kernel/mac80211/patches/subsys/337-mac80211-increase-quantum-for-airtime-scheduler.patch b/package/kernel/mac80211/patches/subsys/337-mac80211-increase-quantum-for-airtime-scheduler.patch
new file mode 100644 (file)
index 0000000..74e8576
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/337-mac80211-increase-quantum-for-airtime-scheduler.patch
@@ -0,0 +1,53 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sun, 26 Jun 2022 11:43:25 +0200
+Subject: [PATCH] mac80211: increase quantum for airtime scheduler
+
+Given the typical AQL budget and queue length, a quantum of 256 with the
+default station weight often requires iterating over all queues frequently,
+until one of them becomes eligible.
+Improve performance by using 8 times station weight as scheduler quantum
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/ieee80211_i.h
++++ b/net/mac80211/ieee80211_i.h
+@@ -90,6 +90,8 @@ extern const u8 ieee80211_ac_to_qos_mask
+  */
+ #define AIRTIME_ACTIVE_DURATION (HZ / 10)
+ 
++#define AIRTIME_QUANTUM_SHIFT 3
++
+ struct ieee80211_bss {
+       u32 device_ts_beacon, device_ts_presp;
+ 
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3894,7 +3894,7 @@ struct ieee80211_txq *ieee80211_next_txq
+ 
+               if (deficit < 0)
+                       sta->airtime[txqi->txq.ac].deficit +=
+-                              sta->airtime_weight;
++                              sta->airtime_weight << AIRTIME_QUANTUM_SHIFT;
+ 
+               if (deficit < 0 || !aql_check) {
+                       list_move_tail(&txqi->schedule_order,
+@@ -4037,7 +4037,8 @@ bool ieee80211_txq_may_transmit(struct i
+               }
+               sta = container_of(iter->txq.sta, struct sta_info, sta);
+               if (ieee80211_sta_deficit(sta, ac) < 0)
+-                      sta->airtime[ac].deficit += sta->airtime_weight;
++                      sta->airtime[ac].deficit += sta->airtime_weight <<
++                                                  AIRTIME_QUANTUM_SHIFT;
+               list_move_tail(&iter->schedule_order, &local->active_txqs[ac]);
+       }
+ 
+@@ -4045,7 +4046,7 @@ bool ieee80211_txq_may_transmit(struct i
+       if (sta->airtime[ac].deficit >= 0)
+               goto out;
+ 
+-      sta->airtime[ac].deficit += sta->airtime_weight;
++      sta->airtime[ac].deficit += sta->airtime_weight << AIRTIME_QUANTUM_SHIFT;
+       list_move_tail(&txqi->schedule_order, &local->active_txqs[ac]);
+       spin_unlock_bh(&local->active_txq_lock[ac]);
+