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authorFelix Fietkau <nbd@nbd.name>2021-12-14 17:58:14 +0100
committerFelix Fietkau <nbd@nbd.name>2021-12-17 15:03:05 +0100
commit87def9efd8cee66da3bd3961671e580282427c2e (patch)
tree9bf2bbd279f15af9b30cf2ee7bdd122187072e8c
parent9090e0be4d4d6dc26b7789f2a5a62dbb0b124cfb (diff)
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mac80211: optimize airtime fairness code to reduce cpu usage
Signed-off-by: Felix Fietkau <nbd@nbd.name>
-rw-r--r--package/kernel/mac80211/patches/subsys/311-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch60
1 files changed, 60 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/subsys/311-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch b/package/kernel/mac80211/patches/subsys/311-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch
new file mode 100644
index 0000000000..d4472ac83d
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/311-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch
@@ -0,0 +1,60 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Tue, 14 Dec 2021 17:53:12 +0100
+Subject: [PATCH] mac80211: use coarse boottime for airtime fairness code
+
+The time values used by the airtime fairness code only need to be accurate
+enough to cover station activity detection.
+Using ktime_get_coarse_boottime_ns instead of ktime_get_boottime_ns will
+drop the accuracy down to jiffies intervals, but at the same time saves
+a lot of CPU cycles in a hot path
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3827,7 +3827,7 @@ struct ieee80211_txq *ieee80211_next_txq
+ {
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct airtime_sched_info *air_sched;
+- u64 now = ktime_get_boottime_ns();
++ u64 now = ktime_get_coarse_boottime_ns();
+ struct ieee80211_txq *ret = NULL;
+ struct airtime_info *air_info;
+ struct txq_info *txqi = NULL;
+@@ -3954,7 +3954,7 @@ void ieee80211_update_airtime_weight(str
+ u64 weight_sum = 0;
+
+ if (unlikely(!now))
+- now = ktime_get_boottime_ns();
++ now = ktime_get_coarse_boottime_ns();
+
+ lockdep_assert_held(&air_sched->lock);
+
+@@ -3980,7 +3980,7 @@ void ieee80211_schedule_txq(struct ieee8
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct txq_info *txqi = to_txq_info(txq);
+ struct airtime_sched_info *air_sched;
+- u64 now = ktime_get_boottime_ns();
++ u64 now = ktime_get_coarse_boottime_ns();
+ struct airtime_info *air_info;
+ u8 ac = txq->ac;
+ bool was_active;
+@@ -4038,7 +4038,7 @@ static void __ieee80211_unschedule_txq(s
+
+ if (!purge)
+ airtime_set_active(air_sched, air_info,
+- ktime_get_boottime_ns());
++ ktime_get_coarse_boottime_ns());
+
+ rb_erase_cached(&txqi->schedule_order,
+ &air_sched->active_txqs);
+@@ -4126,7 +4126,7 @@ bool ieee80211_txq_may_transmit(struct i
+ if (RB_EMPTY_NODE(&txqi->schedule_order))
+ goto out;
+
+- now = ktime_get_boottime_ns();
++ now = ktime_get_coarse_boottime_ns();
+
+ /* Like in ieee80211_next_txq(), make sure the first station in the
+ * scheduling order is eligible for transmission to avoid starvation.