Commit 3ff901cb authored by Felix Fietkau's avatar Felix Fietkau Committed by Johannes Berg
Browse files

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: default avatarFelix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20200724182816.18678-1-nbd@nbd.name


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 1303a51c

net/mac80211/airtime.c

+21 −5
Original line number Diff line number Diff line
@@ -551,7 +551,7 @@ EXPORT_SYMBOL_GPL(ieee80211_calc_tx_airtime); 
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(struct ieee80211_hw *hw, 
	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;



		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 ieee80211_calc_tx_airtime_rate(hw,

						      &sta->tx_stats.last_rate,

						      band, len);

		return airtime;

	}



	if (!conf)

net/mac80211/ieee80211_i.h

+1 −1
Original line number Diff line number Diff line
@@ -2290,7 +2290,7 @@ extern const struct ethtool_ops ieee80211_ethtool_ops; 
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 CONFIG_MAC80211_NOINLINE

#define debug_noinline noinline

#else

net/mac80211/tx.c

+2 −1
Original line number Diff line number Diff line
@@ -3722,10 +3722,11 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, 


	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,