Commit 942741da authored by Felix Fietkau's avatar Felix Fietkau Committed by Johannes Berg
Browse files

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



This reverts commits 6a789ba6 and
2433647b.

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: default avatarFelix Fietkau <nbd@nbd.name>
Acked-by: default avatarToke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220625212411.36675-1-nbd@nbd.name


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 7f884baa

include/net/mac80211.h

+14 −3
Original line number Diff line number Diff line
@@ -6832,6 +6832,9 @@ static inline void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac) 
{

}



void __ieee80211_schedule_txq(struct ieee80211_hw *hw,

			      struct ieee80211_txq *txq, bool force);



/**

 * ieee80211_schedule_txq - schedule a TXQ for transmission

 *
@@ -6844,7 +6847,11 @@ static inline void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac) 
 * The driver may call this function if it has buffered packets for

 * this TXQ internally.

 */

void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq);

static inline void

ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)

{

	__ieee80211_schedule_txq(hw, txq, true);

}



/**

 * ieee80211_return_txq - return a TXQ previously acquired by ieee80211_next_txq()
@@ -6856,8 +6863,12 @@ void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq); 
 * The driver may set force=true if it has buffered packets for this TXQ

 * internally.

 */

void ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq,

			  bool force);

static inline void

ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq,

		     bool force)

{

	__ieee80211_schedule_txq(hw, txq, force);

}



/**

 * ieee80211_txq_may_transmit - check whether TXQ is allowed to transmit

net/mac80211/cfg.c

+1 −34
Original line number Diff line number Diff line
@@ -1581,38 +1581,6 @@ static void sta_apply_mesh_params(struct ieee80211_local *local, 
#endif

}



static void sta_apply_airtime_params(struct ieee80211_local *local,

				     struct sta_info *sta,

				     struct station_parameters *params)

{

	u8 ac;



	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {

		struct airtime_sched_info *air_sched = &local->airtime[ac];

		struct airtime_info *air_info = &sta->airtime[ac];

		struct txq_info *txqi;

		u8 tid;



		spin_lock_bh(&air_sched->lock);

		for (tid = 0; tid < IEEE80211_NUM_TIDS + 1; tid++) {

			if (air_info->weight == params->airtime_weight ||

			    !sta->sta.txq[tid] ||

			    ac != ieee80211_ac_from_tid(tid))

				continue;



			airtime_weight_set(air_info, params->airtime_weight);



			txqi = to_txq_info(sta->sta.txq[tid]);

			if (RB_EMPTY_NODE(&txqi->schedule_order))

				continue;



			ieee80211_update_airtime_weight(local, air_sched,

							0, true);

		}

		spin_unlock_bh(&air_sched->lock);

	}

}



static int sta_apply_parameters(struct ieee80211_local *local,

				struct sta_info *sta,

				struct station_parameters *params)
@@ -1811,8 +1779,7 @@ static int sta_apply_parameters(struct ieee80211_local *local, 
		sta_apply_mesh_params(local, sta, params);



	if (params->airtime_weight)

		sta_apply_airtime_params(local, sta, params);



		sta->airtime_weight = params->airtime_weight;



	/* set the STA state after all sta info from usermode has been set */

	if (test_sta_flag(sta, WLAN_STA_TDLS_PEER) ||

net/mac80211/debugfs.c

+13 −57
Original line number Diff line number Diff line
@@ -216,14 +216,14 @@ static ssize_t aql_txq_limit_read(struct file *file, 
			"VI	%u		%u\n"

			"BE	%u		%u\n"

			"BK	%u		%u\n",

			local->airtime[IEEE80211_AC_VO].aql_txq_limit_low,

			local->airtime[IEEE80211_AC_VO].aql_txq_limit_high,

			local->airtime[IEEE80211_AC_VI].aql_txq_limit_low,

			local->airtime[IEEE80211_AC_VI].aql_txq_limit_high,

			local->airtime[IEEE80211_AC_BE].aql_txq_limit_low,

			local->airtime[IEEE80211_AC_BE].aql_txq_limit_high,

			local->airtime[IEEE80211_AC_BK].aql_txq_limit_low,

			local->airtime[IEEE80211_AC_BK].aql_txq_limit_high);

			local->aql_txq_limit_low[IEEE80211_AC_VO],

			local->aql_txq_limit_high[IEEE80211_AC_VO],

			local->aql_txq_limit_low[IEEE80211_AC_VI],

			local->aql_txq_limit_high[IEEE80211_AC_VI],

			local->aql_txq_limit_low[IEEE80211_AC_BE],

			local->aql_txq_limit_high[IEEE80211_AC_BE],

			local->aql_txq_limit_low[IEEE80211_AC_BK],

			local->aql_txq_limit_high[IEEE80211_AC_BK]);

	return simple_read_from_buffer(user_buf, count, ppos,

				       buf, len);

}
@@ -255,11 +255,11 @@ static ssize_t aql_txq_limit_write(struct file *file, 
	if (ac >= IEEE80211_NUM_ACS)

		return -EINVAL;



	q_limit_low_old = local->airtime[ac].aql_txq_limit_low;

	q_limit_high_old = local->airtime[ac].aql_txq_limit_high;

	q_limit_low_old = local->aql_txq_limit_low[ac];

	q_limit_high_old = local->aql_txq_limit_high[ac];



	local->airtime[ac].aql_txq_limit_low = q_limit_low;

	local->airtime[ac].aql_txq_limit_high = q_limit_high;

	local->aql_txq_limit_low[ac] = q_limit_low;

	local->aql_txq_limit_high[ac] = q_limit_high;



	mutex_lock(&local->sta_mtx);

	list_for_each_entry(sta, &local->sta_list, list) {
@@ -382,46 +382,6 @@ static const struct file_operations force_tx_status_ops = { 
	.llseek = default_llseek,

};



static ssize_t airtime_read(struct file *file,

			    char __user *user_buf,

			    size_t count,

			    loff_t *ppos)

{

	struct ieee80211_local *local = file->private_data;

	char buf[200];

	u64 v_t[IEEE80211_NUM_ACS];

	u64 wt[IEEE80211_NUM_ACS];

	int len = 0, ac;



	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {

		spin_lock_bh(&local->airtime[ac].lock);

		v_t[ac] = local->airtime[ac].v_t;

		wt[ac] = local->airtime[ac].weight_sum;

		spin_unlock_bh(&local->airtime[ac].lock);

	}

	len = scnprintf(buf, sizeof(buf),

			"\tVO         VI         BE         BK\n"

			"Virt-t\t%-10llu %-10llu %-10llu %-10llu\n"

			"Weight\t%-10llu %-10llu %-10llu %-10llu\n",

			v_t[0],

			v_t[1],

			v_t[2],

			v_t[3],

			wt[0],

			wt[1],

			wt[2],

			wt[3]);



	return simple_read_from_buffer(user_buf, count, ppos,

				       buf, len);

}



static const struct file_operations airtime_ops = {

	.read = airtime_read,

	.open = simple_open,

	.llseek = default_llseek,

};



#ifdef CONFIG_PM

static ssize_t reset_write(struct file *file, const char __user *user_buf,

			   size_t count, loff_t *ppos)
@@ -675,11 +635,7 @@ void debugfs_hw_add(struct ieee80211_local *local) 
	if (local->ops->wake_tx_queue)

		DEBUGFS_ADD_MODE(aqm, 0600);



	if (wiphy_ext_feature_isset(local->hw.wiphy,

				    NL80211_EXT_FEATURE_AIRTIME_FAIRNESS)) {

		DEBUGFS_ADD_MODE(airtime, 0600);

	DEBUGFS_ADD_MODE(airtime_flags, 0600);

	}



	DEBUGFS_ADD(aql_txq_limit);

	debugfs_create_u32("aql_threshold", 0600,

net/mac80211/debugfs_netdev.c

+1 −31
Original line number Diff line number Diff line
@@ -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)

net/mac80211/debugfs_sta.c

+12 −12
Original line number Diff line number Diff line
@@ -202,7 +202,7 @@ static ssize_t sta_airtime_read(struct file *file, char __user *userbuf, 
	size_t bufsz = 400;

	char *buf = kzalloc(bufsz, GFP_KERNEL), *p = buf;

	u64 rx_airtime = 0, tx_airtime = 0;

	u64 v_t[IEEE80211_NUM_ACS];

	s64 deficit[IEEE80211_NUM_ACS];

	ssize_t rv;

	int ac;
@@ -210,18 +210,18 @@ static ssize_t sta_airtime_read(struct file *file, char __user *userbuf, 
		return -ENOMEM;



	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {

		spin_lock_bh(&local->airtime[ac].lock);

		spin_lock_bh(&local->active_txq_lock[ac]);

		rx_airtime += sta->airtime[ac].rx_airtime;

		tx_airtime += sta->airtime[ac].tx_airtime;

		v_t[ac] = sta->airtime[ac].v_t;

		spin_unlock_bh(&local->airtime[ac].lock);

		deficit[ac] = sta->airtime[ac].deficit;

		spin_unlock_bh(&local->active_txq_lock[ac]);

	}



	p += scnprintf(p, bufsz + buf - p,

		"RX: %llu us\nTX: %llu us\nWeight: %u\n"

		"Virt-T: VO: %lld us VI: %lld us BE: %lld us BK: %lld us\n",

		rx_airtime, tx_airtime, sta->airtime[0].weight,

		v_t[0], v_t[1], v_t[2], v_t[3]);

		"Deficit: VO: %lld us VI: %lld us BE: %lld us BK: %lld us\n",

		rx_airtime, tx_airtime, sta->airtime_weight,

		deficit[0], deficit[1], deficit[2], deficit[3]);



	rv = simple_read_from_buffer(userbuf, count, ppos, buf, p - buf);

	kfree(buf);
@@ -236,11 +236,11 @@ static ssize_t sta_airtime_write(struct file *file, const char __user *userbuf, 
	int ac;



	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {

		spin_lock_bh(&local->airtime[ac].lock);

		spin_lock_bh(&local->active_txq_lock[ac]);

		sta->airtime[ac].rx_airtime = 0;

		sta->airtime[ac].tx_airtime = 0;

		sta->airtime[ac].v_t = 0;

		spin_unlock_bh(&local->airtime[ac].lock);

		sta->airtime[ac].deficit = sta->airtime_weight;

		spin_unlock_bh(&local->active_txq_lock[ac]);

	}



	return count;
@@ -263,10 +263,10 @@ static ssize_t sta_aql_read(struct file *file, char __user *userbuf, 
		return -ENOMEM;



	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {

		spin_lock_bh(&local->airtime[ac].lock);

		spin_lock_bh(&local->active_txq_lock[ac]);

		q_limit_l[ac] = sta->airtime[ac].aql_limit_low;

		q_limit_h[ac] = sta->airtime[ac].aql_limit_high;

		spin_unlock_bh(&local->airtime[ac].lock);

		spin_unlock_bh(&local->active_txq_lock[ac]);

		q_depth[ac] = atomic_read(&sta->airtime[ac].aql_tx_pending);

	}