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mac80211: fix AQL issues

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- Remove bogus STA txq pending airtime underflow warning
- Improve tx airtime estimation for A-MPDU traffic

Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2020-07-25 10:49:21 +02:00
parent 60f595daab
commit b7727a8005
2 changed files with 112 additions and 0 deletions
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81
package/kernel/mac80211/patches/subsys/305-mac80211-improve-AQL-tx-airtime-estimation.patch Normal file
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@ -0,0 +1,81 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Fri, 24 Jul 2020 20:25:07 +0200
Subject: [PATCH] mac80211: improve AQL tx airtime estimation
AQL does not take into account that most HT/VHT/HE traffic is A-MPDU aggregated.
Because of that, the per-packet airtime overhead is vastly overestimated.
Improve it by assuming an average aggregation length of 16 for non-legacy
traffic if not using the VO AC queue.
This should improve performance with high data rates, especially with multiple
stations
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/mac80211/airtime.c
+++ b/net/mac80211/airtime.c
@@ -551,7 +551,7 @@ EXPORT_SYMBOL_GPL(ieee80211_calc_tx_airt
u32 ieee80211_calc_expected_tx_airtime(struct ieee80211_hw *hw,
struct ieee80211_vif *vif,
struct ieee80211_sta *pubsta,
- int len)
+ int len, bool ampdu)
{
struct ieee80211_supported_band *sband;
struct ieee80211_chanctx_conf *conf;
@@ -572,10 +572,26 @@ u32 ieee80211_calc_expected_tx_airtime(s
if (pubsta) {
struct sta_info *sta = container_of(pubsta, struct sta_info,
sta);
+ struct ieee80211_tx_rate *rate = &sta->tx_stats.last_rate;
+ u32 airtime;
- return ieee80211_calc_tx_airtime_rate(hw,
- &sta->tx_stats.last_rate,
- band, len);
+ if (!(rate->flags & (IEEE80211_TX_RC_VHT_MCS |
+ IEEE80211_TX_RC_MCS)))
+ ampdu = false;
+
+ /*
+ * Assume that HT/VHT transmission on any AC except VO will
+ * use aggregation. Since we don't have reliable reporting
+ * of aggregation length, assume an average of 16.
+ * This will not be very accurate, but much better than simply
+ * assuming un-aggregated tx.
+ */
+ airtime = ieee80211_calc_tx_airtime_rate(hw, rate, band,
+ ampdu ? len * 16 : len);
+ if (ampdu)
+ airtime /= 16;
+
+ return airtime;
}
if (!conf)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -2278,7 +2278,7 @@ extern const struct ethtool_ops ieee8021
u32 ieee80211_calc_expected_tx_airtime(struct ieee80211_hw *hw,
struct ieee80211_vif *vif,
struct ieee80211_sta *pubsta,
- int len);
+ int len, bool ampdu);
#ifdef CPTCFG_MAC80211_NOINLINE
#define debug_noinline noinline
#else
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3694,10 +3694,11 @@ encap_out:
if (vif &&
wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL)) {
+ bool ampdu = txq->ac != IEEE80211_AC_VO;
u32 airtime;
airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
- skb->len);
+ skb->len, ampdu);
if (airtime) {
airtime = ieee80211_info_set_tx_time_est(info, airtime);
ieee80211_sta_update_pending_airtime(local, tx.sta,

31
package/kernel/mac80211/patches/subsys/306-mac80211-remove-STA-txq-pending-airtime-underflow-wa.patch Normal file
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From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 25 Jul 2020 10:42:30 +0200
Subject: [PATCH] mac80211: remove STA txq pending airtime underflow
warning
This warning can trigger if there is a mismatch between frames that were
sent with the sta pointer set vs tx status frames reported for the sta address.
This can happen due to race conditions on re-creating stations, or even
in the case of .sta_add/remove being used instead of .sta_state, which can cause
frames to be sent to a station that has not been uploaded yet.
If there is an actual underflow issue, it should show up in the device airtime
warning below, so it is better to remove this one.
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -1924,9 +1924,7 @@ void ieee80211_sta_update_pending_airtim
if (sta) {
tx_pending = atomic_sub_return(tx_airtime,
&sta->airtime[ac].aql_tx_pending);
- if (WARN_ONCE(tx_pending < 0,
- "STA %pM AC %d txq pending airtime underflow: %u, %u",
- sta->addr, ac, tx_pending, tx_airtime))
+ if (tx_pending < 0)
atomic_cmpxchg(&sta->airtime[ac].aql_tx_pending,
tx_pending, 0);
}