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mac80211: optimize airtime fairness code to reduce cpu usage

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Signed-off-by: Felix Fietkau <nbd@nbd.name>
(cherry-picked from commit 87def9efd8)
This commit is contained in:
Felix Fietkau 2021-12-14 17:58:14 +01:00
parent 5414aa88ae
commit e1b79b1dc3
1 changed files with 60 additions and 0 deletions
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package/kernel/mac80211/patches/subsys/395-mac80211-use-coarse-boottime-for-airtime-fairness-co.patch Normal file
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@ -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
@@ -3834,7 +3834,7 @@ 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;
@@ -3961,7 +3961,7 @@ 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);
@@ -3987,7 +3987,7 @@ 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;
@@ -4045,7 +4045,7 @@ 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);
@@ -4133,7 +4133,7 @@ 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.