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mac80211: optimize airtime fairness code to reduce cpu usage
Signed-off-by: Felix Fietkau <nbd@nbd.name>
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...el/mac80211/patches/subsys/311-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch
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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 | ||
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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 | ||
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Signed-off-by: Felix Fietkau <nbd@nbd.name> | ||
--- | ||
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--- 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; | ||
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if (unlikely(!now)) | ||
- now = ktime_get_boottime_ns(); | ||
+ now = ktime_get_coarse_boottime_ns(); | ||
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lockdep_assert_held(&air_sched->lock); | ||
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@@ -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 | ||
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if (!purge) | ||
airtime_set_active(air_sched, air_info, | ||
- ktime_get_boottime_ns()); | ||
+ ktime_get_coarse_boottime_ns()); | ||
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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; | ||
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- now = ktime_get_boottime_ns(); | ||
+ now = ktime_get_coarse_boottime_ns(); | ||
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/* Like in ieee80211_next_txq(), make sure the first station in the | ||
* scheduling order is eligible for transmission to avoid starvation. |