--- /dev/null
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 11 Jun 2022 16:34:32 +0200
+Subject: [PATCH] mac80211: improve AQL tx time estimation
+
+If airtime cannot be calculated because of missing or unsupported rate info,
+use the smallest possible non-zero value for estimated tx time.
+This improves handling of these cases by preventing queueing of as many packets
+as the driver/hardware queue can hold for these stations.
+Also slightly improve limiting queueing by explicitly rounding up small values.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/include/net/mac80211.h
++++ b/include/net/mac80211.h
+@@ -1107,20 +1107,24 @@ struct ieee80211_tx_info {
+ };
+ };
+
++#define IEEE80211_TX_TIME_EST_UNIT 4
++
++static inline u16
++ieee80211_info_get_tx_time_est(struct ieee80211_tx_info *info)
++{
++ return info->tx_time_est * IEEE80211_TX_TIME_EST_UNIT;
++}
++
+ static inline u16
+ ieee80211_info_set_tx_time_est(struct ieee80211_tx_info *info, u16 tx_time_est)
+ {
+ /* We only have 10 bits in tx_time_est, so store airtime
+ * in increments of 4us and clamp the maximum to 2**12-1
+ */
+- info->tx_time_est = min_t(u16, tx_time_est, 4095) >> 2;
+- return info->tx_time_est << 2;
+-}
++ tx_time_est = DIV_ROUND_UP(tx_time_est, IEEE80211_TX_TIME_EST_UNIT);
++ info->tx_time_est = min_t(u16, tx_time_est, BIT(10) - 1);
+
+-static inline u16
+-ieee80211_info_get_tx_time_est(struct ieee80211_tx_info *info)
+-{
+- return info->tx_time_est << 2;
++ return ieee80211_info_get_tx_time_est(info);
+ }
+
+ /**
+--- a/net/mac80211/status.c
++++ b/net/mac80211/status.c
+@@ -999,6 +999,8 @@ static void __ieee80211_tx_status(struct
+ NULL,
+ skb->len,
+ false);
++ if (!airtime)
++ airtime = IEEE80211_TX_TIME_EST_UNIT;
+
+ ieee80211_register_airtime(txq, airtime, 0);
+ }
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3798,13 +3798,12 @@ encap_out:
+
+ airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
+ skb->len, ampdu);
+- if (airtime) {
+- airtime = ieee80211_info_set_tx_time_est(info, airtime);
+- ieee80211_sta_update_pending_airtime(local, tx.sta,
+- txq->ac,
+- airtime,
+- false);
+- }
++ if (!airtime)
++ airtime = IEEE80211_TX_TIME_EST_UNIT;
++
++ airtime = ieee80211_info_set_tx_time_est(info, airtime);
++ ieee80211_sta_update_pending_airtime(local, tx.sta, txq->ac,
++ airtime, false);
+ }
+
+ return skb;
--- /dev/null
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 11 Jun 2022 17:28:02 +0200
+Subject: [PATCH] mac80211: fix ieee80211_txq_may_transmit regression
+
+After switching to the virtual time based airtime scheduler, there were reports
+that ath10k with tx queueing in push-pull mode was experiencing significant
+latency for some stations.
+The reason for it is the fact that queues from which the ath10k firmware wants
+to pull are getting starved by airtime fairness constraints.
+Theoretically the same issue should have been there before the switch to virtual
+time, however it seems that in the old round-robin implementation it was simply
+looping until the requested txq was considered eligible, which led to it pretty
+much ignoring fairness constraints anyway.
+
+In order to fix the immediate regression, let's make bypassing airtime fairness
+explicit for now.
+Also update the documentation for ieee80211_txq_may_transmit, which was still
+referring to implementation details of the old round-robin scheduler
+
+Fixes: 2433647bc8d9 ("mac80211: Switch to a virtual time-based airtime scheduler")
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/include/net/mac80211.h
++++ b/include/net/mac80211.h
+@@ -6700,22 +6700,11 @@ void ieee80211_return_txq(struct ieee802
+ /**
+ * ieee80211_txq_may_transmit - check whether TXQ is allowed to transmit
+ *
+- * This function is used to check whether given txq is allowed to transmit by
+- * the airtime scheduler, and can be used by drivers to access the airtime
+- * fairness accounting without going using the scheduling order enfored by
+- * next_txq().
++ * Returns %true if there is remaining AQL budget for the tx queue and %false
++ * if it should be throttled. It will also mark the queue as active for the
++ * airtime scheduler.
+ *
+- * Returns %true if the airtime scheduler thinks the TXQ should be allowed to
+- * transmit, and %false if it should be throttled. This function can also have
+- * the side effect of rotating the TXQ in the scheduler rotation, which will
+- * eventually bring the deficit to positive and allow the station to transmit
+- * again.
+- *
+- * The API ieee80211_txq_may_transmit() also ensures that TXQ list will be
+- * aligned against driver's own round-robin scheduler list. i.e it rotates
+- * the TXQ list till it makes the requested node becomes the first entry
+- * in TXQ list. Thus both the TXQ list and driver's list are in sync. If this
+- * function returns %true, the driver is expected to schedule packets
++ * If this function returns %true, the driver is expected to schedule packets
+ * for transmission, and then return the TXQ through ieee80211_return_txq().
+ *
+ * @hw: pointer as obtained from ieee80211_alloc_hw()
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -4100,15 +4100,13 @@ EXPORT_SYMBOL(ieee80211_txq_airtime_chec
+ bool ieee80211_txq_may_transmit(struct ieee80211_hw *hw,
+ struct ieee80211_txq *txq)
+ {
+- struct txq_info *first_txqi = NULL, *txqi = to_txq_info(txq);
+ struct ieee80211_local *local = hw_to_local(hw);
++ struct txq_info *txqi = to_txq_info(txq);
+ struct airtime_sched_info *air_sched;
+ struct airtime_info *air_info;
+- struct rb_node *node = NULL;
+ bool ret = false;
+ u64 now;
+
+-
+ if (!ieee80211_txq_airtime_check(hw, txq))
+ return false;
+
+@@ -4120,19 +4118,6 @@ bool ieee80211_txq_may_transmit(struct i
+
+ 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.
+- */
+- node = rb_first_cached(&air_sched->active_txqs);
+- if (node) {
+- first_txqi = container_of(node, struct txq_info,
+- schedule_order);
+- air_info = to_airtime_info(&first_txqi->txq);
+-
+- if (air_sched->v_t < air_info->v_t)
+- airtime_catchup_v_t(air_sched, air_info->v_t, now);
+- }
+-
+ air_info = to_airtime_info(&txqi->txq);
+ if (air_info->v_t <= air_sched->v_t) {
+ air_sched->last_schedule_activity = now;
/* To avoid divisions in the fast path, we keep pre-computed reciprocals for
* airtime weight calculations. There are two different weights to keep track
* of: The per-station weight and the sum of weights per phy.
-@@ -1750,6 +1764,7 @@ static inline void init_airtime_info(str
+@@ -1749,6 +1763,7 @@ static inline void init_airtime_info(str
air_info->aql_limit_high = air_sched->aql_txq_limit_high;
airtime_weight_set(air_info, IEEE80211_DEFAULT_AIRTIME_WEIGHT);
INIT_LIST_HEAD(&air_info->list);
WARN_ON_ONCE(softirq_count() == 0);
-@@ -3791,21 +3801,26 @@ begin:
+@@ -3791,20 +3801,35 @@ begin:
encap_out:
IEEE80211_SKB_CB(skb)->control.vif = vif;
-
- airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
- skb->len, ampdu);
-- if (airtime) {
-- airtime = ieee80211_info_set_tx_time_est(info, airtime);
-- ieee80211_sta_update_pending_airtime(local, tx.sta,
-- txq->ac,
-- airtime,
-- false);
-- }
+- if (!airtime)
+- airtime = IEEE80211_TX_TIME_EST_UNIT;
+-
+- airtime = ieee80211_info_set_tx_time_est(info, airtime);
+- ieee80211_sta_update_pending_airtime(local, tx.sta, txq->ac,
+- airtime, false);
- }
+ if (!vif)
+ return skb;
+ airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
+ skb->len, ampdu);
+ if (!airtime)
-+ return skb;
++ airtime = IEEE80211_TX_TIME_EST_UNIT;
+
++ /*
++ * Tx queue scheduling always happens in airtime order and queues are
++ * sorted by virtual time + pending AQL budget.
++ * If AQL is not supported, pending AQL budget is always zero.
++ * If airtime fairness is not supported, virtual time won't be directly
++ * increased by driver tx completion.
++ * Because of that, we register estimated tx time as airtime if either
++ * AQL or ATF support is missing.
++ */
+ if (!wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL) ||
+ !wiphy_ext_feature_isset(local->hw.wiphy,
+ NL80211_EXT_FEATURE_AIRTIME_FAIRNESS))
return skb;
-@@ -3816,85 +3831,95 @@ out:
+@@ -3815,85 +3840,92 @@ out:
}
EXPORT_SYMBOL(ieee80211_tx_dequeue);
-+static void
++static struct ieee80211_txq *
+airtime_info_next_txq_idx(struct airtime_info *air_info)
+{
+ air_info->txq_idx++;
+ if (air_info->txq_idx >= ARRAY_SIZE(air_info->txq) ||
+ !air_info->txq[air_info->txq_idx])
+ air_info->txq_idx = 0;
++ return air_info->txq[air_info->txq_idx];
+}
+
struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac)
-
- if (!ieee80211_txq_airtime_check(hw, &txqi->txq)) {
- first = false;
-+ airtime_info_next_txq_idx(air_info);
++ txq = airtime_info_next_txq_idx(air_info);
+ txq_idx = air_info->txq_idx;
-+ txq = air_info->txq[txq_idx];
-+ if (!txq || !ieee80211_txq_airtime_check(hw, txq))
++ if (!ieee80211_txq_airtime_check(hw, txq))
goto begin;
+
+ while (1) {
+ if (txq_has_queue(txq))
+ break;
+
-+ airtime_info_next_txq_idx(air_info);
-+ txq = air_info->txq[air_info->txq_idx];
++ txq = airtime_info_next_txq_idx(air_info);
+ if (txq_idx == air_info->txq_idx)
+ goto begin;
-+ }
-+
-+ if (air_info->v_t_cur > air_sched->v_t) {
-+ if (node == airtime_sched_peek(&air_sched->active_txqs))
-+ airtime_catchup_v_t(air_sched, air_info->v_t_cur, now);
}
++ if (air_info->v_t_cur > air_sched->v_t)
++ airtime_catchup_v_t(air_sched, air_info->v_t_cur, now);
++
air_sched->schedule_pos = node;
air_sched->last_schedule_activity = now;
- ret = &txqi->txq;
struct ieee80211_local *local = hw_to_local(hw);
struct txq_info *txqi = to_txq_info(txq);
struct airtime_sched_info *air_sched;
-@@ -3902,41 +3927,7 @@ void ieee80211_resort_txq(struct ieee802
+@@ -3901,41 +3933,7 @@ void ieee80211_resort_txq(struct ieee802
air_sched = &local->airtime[txq->ac];
lockdep_assert_held(&air_sched->lock);
}
void ieee80211_update_airtime_weight(struct ieee80211_local *local,
-@@ -3985,7 +3976,7 @@ void ieee80211_schedule_txq(struct ieee8
+@@ -3984,7 +3982,7 @@ void ieee80211_schedule_txq(struct ieee8
was_active = airtime_is_active(air_info, now);
airtime_set_active(air_sched, air_info, now);
goto out;
/* If the station has been inactive for a while, catch up its v_t so it
-@@ -3997,7 +3988,7 @@ void ieee80211_schedule_txq(struct ieee8
+@@ -3996,7 +3994,7 @@ void ieee80211_schedule_txq(struct ieee8
air_info->v_t = air_sched->v_t;
ieee80211_update_airtime_weight(local, air_sched, now, !was_active);
out:
spin_unlock_bh(&air_sched->lock);
-@@ -4023,19 +4014,10 @@ static void __ieee80211_unschedule_txq(s
- ieee80211_update_airtime_weight(local, air_sched, 0, true);
- }
+@@ -4017,24 +4015,14 @@ static void __ieee80211_unschedule_txq(s
+
+ lockdep_assert_held(&air_sched->lock);
++ airtime_sched_delete(&air_sched->active_txqs, &air_info->schedule_order);
+ if (purge) {
+ list_del_init(&air_info->list);
+ ieee80211_update_airtime_weight(local, air_sched, 0, true);
+- }
+-
- if (RB_EMPTY_NODE(&txqi->schedule_order))
- return;
-
- if (air_sched->schedule_pos == &txqi->schedule_order)
- air_sched->schedule_pos = rb_prev(&txqi->schedule_order);
-
-+ airtime_sched_delete(&air_sched->active_txqs, &air_info->schedule_order);
- if (!purge)
+- if (!purge)
++ } else {
airtime_set_active(air_sched, air_info,
ktime_get_coarse_boottime_ns());
-
- rb_erase_cached(&txqi->schedule_order,
- &air_sched->active_txqs);
- RB_CLEAR_NODE(&txqi->schedule_order);
++ }
}
void ieee80211_unschedule_txq(struct ieee80211_hw *hw,
-@@ -4055,14 +4037,24 @@ void ieee80211_return_txq(struct ieee802
+@@ -4054,14 +4042,22 @@ void ieee80211_return_txq(struct ieee802
{
struct ieee80211_local *local = hw_to_local(hw);
struct txq_info *txqi = to_txq_info(txq);
- spin_unlock_bh(&local->airtime[txq->ac].lock);
+ spin_lock_bh(&air_sched->lock);
-+ if (!ieee80211_txq_airtime_check(hw, &txqi->txq))
-+ airtime_sched_delete(&air_sched->active_txqs,
-+ &air_info->schedule_order);
-+ else if (txq_has_queue(txq) || force)
++ if (force || (txq_has_queue(txq) &&
++ ieee80211_txq_airtime_check(hw, &txqi->txq)))
+ __ieee80211_insert_txq(local, air_sched, txqi);
+ else
+ __ieee80211_unschedule_txq(hw, txq, false);
}
EXPORT_SYMBOL(ieee80211_return_txq);
-@@ -4101,46 +4093,48 @@ EXPORT_SYMBOL(ieee80211_txq_airtime_chec
- bool ieee80211_txq_may_transmit(struct ieee80211_hw *hw,
- struct ieee80211_txq *txq)
- {
-- struct txq_info *first_txqi = NULL, *txqi = to_txq_info(txq);
-+ struct txq_info *txqi = to_txq_info(txq);
- struct ieee80211_local *local = hw_to_local(hw);
- struct airtime_sched_info *air_sched;
-+ struct airtime_sched_node *node = NULL;
- struct airtime_info *air_info;
-- struct rb_node *node = NULL;
- bool ret = false;
-+ u32 aql_slack;
- u64 now;
-
--
- if (!ieee80211_txq_airtime_check(hw, txq))
- return false;
-
+@@ -4113,9 +4109,6 @@ bool ieee80211_txq_may_transmit(struct i
air_sched = &local->airtime[txq->ac];
spin_lock_bh(&air_sched->lock);
-
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.
- */
-- node = rb_first_cached(&air_sched->active_txqs);
-+ node = airtime_sched_peek(&air_sched->active_txqs);
- if (node) {
-- first_txqi = container_of(node, struct txq_info,
-- schedule_order);
-- air_info = to_airtime_info(&first_txqi->txq);
-+ air_info = container_of(node, struct airtime_info,
-+ schedule_order);
-
- if (air_sched->v_t < air_info->v_t)
- airtime_catchup_v_t(air_sched, air_info->v_t, now);
- }
-
air_info = to_airtime_info(&txqi->txq);
-- if (air_info->v_t <= air_sched->v_t) {
-+ aql_slack = air_info->aql_limit_low;
-+ aql_slack *= air_info->weight_reciprocal;
-+ aql_slack >>= IEEE80211_RECIPROCAL_SHIFT_STA - IEEE80211_WEIGHT_SHIFT;
-+ /*
-+ * add extra slack of aql_limit_low in order to avoid queue
-+ * starvation when bypassing normal scheduling order
-+ */
-+ if (air_info->v_t <= air_sched->v_t + aql_slack) {
- air_sched->last_schedule_activity = now;
+@@ -4124,7 +4117,6 @@ bool ieee80211_txq_may_transmit(struct i
ret = true;
}
spin_unlock_bh(&air_sched->lock);
return ret;
}
-@@ -4151,9 +4145,7 @@ void ieee80211_txq_schedule_start(struct
+@@ -4135,9 +4127,7 @@ void ieee80211_txq_schedule_start(struct
struct ieee80211_local *local = hw_to_local(hw);
struct airtime_sched_info *air_sched = &local->airtime[ac];
projects / thirdparty / openwrt.git / commitdiff
