wifi: mac80211: switch airtime fairness back to deficit round-robin scheduling

This reverts commits 6a789ba679d652587532cec2a0e0274fda172f3b and
2433647bc8d983a543e7d31b41ca2de1c7e2c198.

The virtual time scheduler code has a number of issues:
- queues slowed down by hardware/firmware powersave handling were not properly
  handled.
- on ath10k in push-pull mode, tx queues that the driver tries to pull from
  were starved, causing excessive latency
- delay between tx enqueue and reported airtime use were causing excessively
  bursty tx behavior

The bursty behavior may also be present on the round-robin scheduler, but there
it is much easier to fix without introducing additional regressions

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220625212411.36675-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 1 insertions, 31 deletions

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index dfb194e15018..ead917501d6c 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -510,34 +510,6 @@ static ssize_t ieee80211_if_fmt_aqm(
 }
 IEEE80211_IF_FILE_R(aqm);
 
-static ssize_t ieee80211_if_fmt_airtime(
-	const struct ieee80211_sub_if_data *sdata, char *buf, int buflen)
-{
-	struct ieee80211_local *local = sdata->local;
-	struct ieee80211_txq *txq = sdata->vif.txq;
-	struct airtime_info *air_info;
-	int len;
-
-	if (!txq)
-		return 0;
-
-	spin_lock_bh(&local->airtime[txq->ac].lock);
-	air_info = to_airtime_info(txq);
-	len = scnprintf(buf,
-			buflen,
-			"RX: %llu us\nTX: %llu us\nWeight: %u\n"
-			"Virt-T: %lld us\n",
-			air_info->rx_airtime,
-			air_info->tx_airtime,
-			air_info->weight,
-			air_info->v_t);
-	spin_unlock_bh(&local->airtime[txq->ac].lock);
-
-	return len;
-}
-
-IEEE80211_IF_FILE_R(airtime);
-
 IEEE80211_IF_FILE(multicast_to_unicast, u.ap.multicast_to_unicast, HEX);
 
 /* IBSS attributes */
@@ -683,10 +655,8 @@ static void add_common_files(struct ieee80211_sub_if_data *sdata)
 
 	if (sdata->local->ops->wake_tx_queue &&
 	    sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
-	    sdata->vif.type != NL80211_IFTYPE_NAN) {
+	    sdata->vif.type != NL80211_IFTYPE_NAN)
 		DEBUGFS_ADD(aqm);
-		DEBUGFS_ADD(airtime);
-	}
 }
 
 static void add_sta_files(struct ieee80211_sub_if_data *sdata)