mac80211: backport airtime queue limits support

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 446 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/subsys/310-mac80211-Implement-Airtime-based-Queue-Limit-AQL.patch b/package/kernel/mac80211/patches/subsys/310-mac80211-Implement-Airtime-based-Queue-Limit-AQL.patch
new file mode 100644
index 0000000000..4eb5eb63a2
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/310-mac80211-Implement-Airtime-based-Queue-Limit-AQL.patch
@@ -0,0 +1,446 @@
+From: Kan Yan <kyan@google.com>
+Date: Mon, 18 Nov 2019 22:06:09 -0800
+Subject: [PATCH] mac80211: Implement Airtime-based Queue Limit (AQL)
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+In order for the Fq_CoDel algorithm integrated in mac80211 layer to operate
+effectively to control excessive queueing latency, the CoDel algorithm
+requires an accurate measure of how long packets stays in the queue, AKA
+sojourn time. The sojourn time measured at the mac80211 layer doesn't
+include queueing latency in the lower layer (firmware/hardware) and CoDel
+expects lower layer to have a short queue. However, most 802.11ac chipsets
+offload tasks such TX aggregation to firmware or hardware, thus have a deep
+lower layer queue.
+
+Without a mechanism to control the lower layer queue size, packets only
+stay in mac80211 layer transiently before being sent to firmware queue.
+As a result, the sojourn time measured by CoDel in the mac80211 layer is
+almost always lower than the CoDel latency target, hence CoDel does little
+to control the latency, even when the lower layer queue causes excessive
+latency.
+
+The Byte Queue Limits (BQL) mechanism is commonly used to address the
+similar issue with wired network interface. However, this method cannot be
+applied directly to the wireless network interface. "Bytes" is not a
+suitable measure of queue depth in the wireless network, as the data rate
+can vary dramatically from station to station in the same network, from a
+few Mbps to over Gbps.
+
+This patch implements an Airtime-based Queue Limit (AQL) to make CoDel work
+effectively with wireless drivers that utilized firmware/hardware
+offloading. AQL allows each txq to release just enough packets to the lower
+layer to form 1-2 large aggregations to keep hardware fully utilized and
+retains the rest of the frames in mac80211 layer to be controlled by the
+CoDel algorithm.
+
+Signed-off-by: Kan Yan <kyan@google.com>
+[ Toke: Keep API to set pending airtime internal, fix nits in commit msg ]
+Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
+Link: https://lore.kernel.org/r/20191119060610.76681-4-kyan@google.com
+Signed-off-by: Johannes Berg <johannes.berg@intel.com>
+---
+
+--- a/include/net/cfg80211.h
++++ b/include/net/cfg80211.h
+@@ -2603,6 +2603,13 @@ enum wiphy_params_flags {
+ 
+ #define IEEE80211_DEFAULT_AIRTIME_WEIGHT	256
+ 
++/* The per TXQ device queue limit in airtime */
++#define IEEE80211_DEFAULT_AQL_TXQ_LIMIT_L	5000
++#define IEEE80211_DEFAULT_AQL_TXQ_LIMIT_H	12000
++
++/* The per interface airtime threshold to switch to lower queue limit */
++#define IEEE80211_AQL_THRESHOLD			24000
++
+ /**
+  * struct cfg80211_pmksa - PMK Security Association
+  *
+--- a/include/net/mac80211.h
++++ b/include/net/mac80211.h
+@@ -5559,6 +5559,18 @@ void ieee80211_sta_register_airtime(stru
+ 				    u32 tx_airtime, u32 rx_airtime);
+ 
+ /**
++ * ieee80211_txq_airtime_check - check if a txq can send frame to device
++ *
++ * @hw: pointer obtained from ieee80211_alloc_hw()
++ * @txq: pointer obtained from station or virtual interface
++ *
++ * Return true if the AQL's airtime limit has not been reached and the txq can
++ * continue to send more packets to the device. Otherwise return false.
++ */
++bool
++ieee80211_txq_airtime_check(struct ieee80211_hw *hw, struct ieee80211_txq *txq);
++
++/**
+  * ieee80211_iter_keys - iterate keys programmed into the device
+  * @hw: pointer obtained from ieee80211_alloc_hw()
+  * @vif: virtual interface to iterate, may be %NULL for all
+--- a/net/mac80211/debugfs.c
++++ b/net/mac80211/debugfs.c
+@@ -148,6 +148,87 @@ static const struct file_operations aqm_
+ 	.llseek = default_llseek,
+ };
+ 
++static ssize_t aql_txq_limit_read(struct file *file,
++				  char __user *user_buf,
++				  size_t count,
++				  loff_t *ppos)
++{
++	struct ieee80211_local *local = file->private_data;
++	char buf[400];
++	int len = 0;
++
++	len = scnprintf(buf, sizeof(buf),
++			"AC	AQL limit low	AQL limit high\n"
++			"VO	%u		%u\n"
++			"VI	%u		%u\n"
++			"BE	%u		%u\n"
++			"BK	%u		%u\n",
++			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);
++}
++
++static ssize_t aql_txq_limit_write(struct file *file,
++				   const char __user *user_buf,
++				   size_t count,
++				   loff_t *ppos)
++{
++	struct ieee80211_local *local = file->private_data;
++	char buf[100];
++	size_t len;
++	u32 ac, q_limit_low, q_limit_high, q_limit_low_old, q_limit_high_old;
++	struct sta_info *sta;
++
++	if (count > sizeof(buf))
++		return -EINVAL;
++
++	if (copy_from_user(buf, user_buf, count))
++		return -EFAULT;
++
++	buf[sizeof(buf) - 1] = 0;
++	len = strlen(buf);
++	if (len > 0 && buf[len - 1] == '\n')
++		buf[len - 1] = 0;
++
++	if (sscanf(buf, "%u %u %u", &ac, &q_limit_low, &q_limit_high) != 3)
++		return -EINVAL;
++
++	if (ac >= IEEE80211_NUM_ACS)
++		return -EINVAL;
++
++	q_limit_low_old = local->aql_txq_limit_low[ac];
++	q_limit_high_old = local->aql_txq_limit_high[ac];
++
++	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) {
++		/* If a sta has customized queue limits, keep it */
++		if (sta->airtime[ac].aql_limit_low == q_limit_low_old &&
++		    sta->airtime[ac].aql_limit_high == q_limit_high_old) {
++			sta->airtime[ac].aql_limit_low = q_limit_low;
++			sta->airtime[ac].aql_limit_high = q_limit_high;
++		}
++	}
++	mutex_unlock(&local->sta_mtx);
++	return count;
++}
++
++static const struct file_operations aql_txq_limit_ops = {
++	.write = aql_txq_limit_write,
++	.read = aql_txq_limit_read,
++	.open = simple_open,
++	.llseek = default_llseek,
++};
++
+ static ssize_t force_tx_status_read(struct file *file,
+ 				    char __user *user_buf,
+ 				    size_t count,
+@@ -441,6 +522,10 @@ void debugfs_hw_add(struct ieee80211_loc
+ 	debugfs_create_u16("airtime_flags", 0600,
+ 			   phyd, &local->airtime_flags);
+ 
++	DEBUGFS_ADD(aql_txq_limit);
++	debugfs_create_u32("aql_threshold", 0600,
++			   phyd, &local->aql_threshold);
++
+ 	statsd = debugfs_create_dir("statistics", phyd);
+ 
+ 	/* if the dir failed, don't put all the other things into the root! */
+--- a/net/mac80211/debugfs_sta.c
++++ b/net/mac80211/debugfs_sta.c
+@@ -197,10 +197,12 @@ static ssize_t sta_airtime_read(struct f
+ {
+ 	struct sta_info *sta = file->private_data;
+ 	struct ieee80211_local *local = sta->sdata->local;
+-	size_t bufsz = 200;
++	size_t bufsz = 400;
+ 	char *buf = kzalloc(bufsz, GFP_KERNEL), *p = buf;
+ 	u64 rx_airtime = 0, tx_airtime = 0;
+ 	s64 deficit[IEEE80211_NUM_ACS];
++	u32 q_depth[IEEE80211_NUM_ACS];
++	u32 q_limit_l[IEEE80211_NUM_ACS], q_limit_h[IEEE80211_NUM_ACS];
+ 	ssize_t rv;
+ 	int ac;
+ 
+@@ -212,19 +214,22 @@ static ssize_t sta_airtime_read(struct f
+ 		rx_airtime += sta->airtime[ac].rx_airtime;
+ 		tx_airtime += sta->airtime[ac].tx_airtime;
+ 		deficit[ac] = sta->airtime[ac].deficit;
++		q_limit_l[ac] = sta->airtime[ac].aql_limit_low;
++		q_limit_h[ac] = sta->airtime[ac].aql_limit_high;
+ 		spin_unlock_bh(&local->active_txq_lock[ac]);
++		q_depth[ac] = atomic_read(&sta->airtime[ac].aql_tx_pending);
+ 	}
+ 
+ 	p += scnprintf(p, bufsz + buf - p,
+ 		"RX: %llu us\nTX: %llu us\nWeight: %u\n"
+-		"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]);
++		"Deficit: VO: %lld us VI: %lld us BE: %lld us BK: %lld us\n"
++		"Q depth: VO: %u us VI: %u us BE: %u us BK: %u us\n"
++		"Q limit[low/high]: VO: %u/%u VI: %u/%u BE: %u/%u BK: %u/%u\n",
++		rx_airtime, tx_airtime, sta->airtime_weight,
++		deficit[0], deficit[1], deficit[2], deficit[3],
++		q_depth[0], q_depth[1], q_depth[2], q_depth[3],
++		q_limit_l[0], q_limit_h[0], q_limit_l[1], q_limit_h[1],
++		q_limit_l[2], q_limit_h[2], q_limit_l[3], q_limit_h[3]),
+ 
+ 	rv = simple_read_from_buffer(userbuf, count, ppos, buf, p - buf);
+ 	kfree(buf);
+@@ -236,7 +241,25 @@ static ssize_t sta_airtime_write(struct
+ {
+ 	struct sta_info *sta = file->private_data;
+ 	struct ieee80211_local *local = sta->sdata->local;
+-	int ac;
++	u32 ac, q_limit_l, q_limit_h;
++	char _buf[100] = {}, *buf = _buf;
++
++	if (count > sizeof(_buf))
++		return -EINVAL;
++
++	if (copy_from_user(buf, userbuf, count))
++		return -EFAULT;
++
++	buf[sizeof(_buf) - 1] = '\0';
++	if (sscanf(buf, "queue limit %u %u %u", &ac, &q_limit_l, &q_limit_h)
++	    != 3)
++		return -EINVAL;
++
++	if (ac >= IEEE80211_NUM_ACS)
++		return -EINVAL;
++
++	sta->airtime[ac].aql_limit_low = q_limit_l;
++	sta->airtime[ac].aql_limit_high = q_limit_h;
+ 
+ 	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+ 		spin_lock_bh(&local->active_txq_lock[ac]);
+--- a/net/mac80211/ieee80211_i.h
++++ b/net/mac80211/ieee80211_i.h
+@@ -1142,6 +1142,10 @@ struct ieee80211_local {
+ 	u16 schedule_round[IEEE80211_NUM_ACS];
+ 
+ 	u16 airtime_flags;
++	u32 aql_txq_limit_low[IEEE80211_NUM_ACS];
++	u32 aql_txq_limit_high[IEEE80211_NUM_ACS];
++	u32 aql_threshold;
++	atomic_t aql_total_pending_airtime;
+ 
+ 	const struct ieee80211_ops *ops;
+ 
+--- a/net/mac80211/main.c
++++ b/net/mac80211/main.c
+@@ -669,8 +669,16 @@ struct ieee80211_hw *ieee80211_alloc_hw_
+ 	for (i = 0; i < IEEE80211_NUM_ACS; i++) {
+ 		INIT_LIST_HEAD(&local->active_txqs[i]);
+ 		spin_lock_init(&local->active_txq_lock[i]);
++		local->aql_txq_limit_low[i] = IEEE80211_DEFAULT_AQL_TXQ_LIMIT_L;
++		local->aql_txq_limit_high[i] =
++			IEEE80211_DEFAULT_AQL_TXQ_LIMIT_H;
+ 	}
+-	local->airtime_flags = AIRTIME_USE_TX | AIRTIME_USE_RX;
++
++	local->airtime_flags = AIRTIME_USE_TX |
++			       AIRTIME_USE_RX |
++			       AIRTIME_USE_AQL;
++	local->aql_threshold = IEEE80211_AQL_THRESHOLD;
++	atomic_set(&local->aql_total_pending_airtime, 0);
+ 
+ 	INIT_LIST_HEAD(&local->chanctx_list);
+ 	mutex_init(&local->chanctx_mtx);
+--- a/net/mac80211/sta_info.c
++++ b/net/mac80211/sta_info.c
+@@ -411,6 +411,9 @@ struct sta_info *sta_info_alloc(struct i
+ 		skb_queue_head_init(&sta->ps_tx_buf[i]);
+ 		skb_queue_head_init(&sta->tx_filtered[i]);
+ 		sta->airtime[i].deficit = sta->airtime_weight;
++		atomic_set(&sta->airtime[i].aql_tx_pending, 0);
++		sta->airtime[i].aql_limit_low = local->aql_txq_limit_low[i];
++		sta->airtime[i].aql_limit_high = local->aql_txq_limit_high[i];
+ 	}
+ 
+ 	for (i = 0; i < IEEE80211_NUM_TIDS; i++)
+@@ -1908,6 +1911,41 @@ void ieee80211_sta_register_airtime(stru
+ }
+ EXPORT_SYMBOL(ieee80211_sta_register_airtime);
+ 
++void ieee80211_sta_update_pending_airtime(struct ieee80211_local *local,
++					  struct sta_info *sta, u8 ac,
++					  u16 tx_airtime, bool tx_completed)
++{
++	int tx_pending;
++
++	if (!tx_completed) {
++		if (sta)
++			atomic_add(tx_airtime,
++				   &sta->airtime[ac].aql_tx_pending);
++
++		atomic_add(tx_airtime, &local->aql_total_pending_airtime);
++		return;
++	}
++
++	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))
++			atomic_cmpxchg(&sta->airtime[ac].aql_tx_pending,
++				       tx_pending, 0);
++	}
++
++	tx_pending = atomic_sub_return(tx_airtime,
++				       &local->aql_total_pending_airtime);
++	if (WARN_ONCE(tx_pending < 0,
++		      "Device %s AC %d pending airtime underflow: %u, %u",
++		      wiphy_name(local->hw.wiphy), ac, tx_pending,
++		      tx_airtime))
++		atomic_cmpxchg(&local->aql_total_pending_airtime,
++			       tx_pending, 0);
++}
++
+ int sta_info_move_state(struct sta_info *sta,
+ 			enum ieee80211_sta_state new_state)
+ {
+--- a/net/mac80211/sta_info.h
++++ b/net/mac80211/sta_info.h
+@@ -127,13 +127,21 @@ enum ieee80211_agg_stop_reason {
+ /* Debugfs flags to enable/disable use of RX/TX airtime in scheduler */
+ #define AIRTIME_USE_TX		BIT(0)
+ #define AIRTIME_USE_RX		BIT(1)
++#define AIRTIME_USE_AQL		BIT(2)
+ 
+ struct airtime_info {
+ 	u64 rx_airtime;
+ 	u64 tx_airtime;
+ 	s64 deficit;
++	atomic_t aql_tx_pending; /* Estimated airtime for frames pending */
++	u32 aql_limit_low;
++	u32 aql_limit_high;
+ };
+ 
++void ieee80211_sta_update_pending_airtime(struct ieee80211_local *local,
++					  struct sta_info *sta, u8 ac,
++					  u16 tx_airtime, bool tx_completed);
++
+ struct sta_info;
+ 
+ /**
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3667,7 +3667,8 @@ struct ieee80211_txq *ieee80211_next_txq
+ {
+ 	struct ieee80211_local *local = hw_to_local(hw);
+ 	struct ieee80211_txq *ret = NULL;
+-	struct txq_info *txqi = NULL;
++	struct txq_info *txqi = NULL, *head = NULL;
++	bool found_eligible_txq = false;
+ 
+ 	spin_lock_bh(&local->active_txq_lock[ac]);
+ 
+@@ -3678,13 +3679,30 @@ struct ieee80211_txq *ieee80211_next_txq
+ 	if (!txqi)
+ 		goto out;
+ 
++	if (txqi == head) {
++		if (!found_eligible_txq)
++			goto out;
++		else
++			found_eligible_txq = false;
++	}
++
++	if (!head)
++		head = txqi;
++
+ 	if (txqi->txq.sta) {
+ 		struct sta_info *sta = container_of(txqi->txq.sta,
+-						struct sta_info, sta);
++						    struct sta_info, sta);
++		bool aql_check = ieee80211_txq_airtime_check(hw, &txqi->txq);
++		s64 deficit = sta->airtime[txqi->txq.ac].deficit;
+ 
+-		if (sta->airtime[txqi->txq.ac].deficit < 0) {
++		if (aql_check)
++			found_eligible_txq = true;
++
++		if (deficit < 0)
+ 			sta->airtime[txqi->txq.ac].deficit +=
+ 				sta->airtime_weight;
++
++		if (deficit < 0 || !aql_check) {
+ 			list_move_tail(&txqi->schedule_order,
+ 				       &local->active_txqs[txqi->txq.ac]);
+ 			goto begin;
+@@ -3738,6 +3756,33 @@ void __ieee80211_schedule_txq(struct iee
+ }
+ EXPORT_SYMBOL(__ieee80211_schedule_txq);
+ 
++bool ieee80211_txq_airtime_check(struct ieee80211_hw *hw,
++				 struct ieee80211_txq *txq)
++{
++	struct sta_info *sta;
++	struct ieee80211_local *local = hw_to_local(hw);
++
++	if (!(local->airtime_flags & AIRTIME_USE_AQL))
++		return true;
++
++	if (!txq->sta)
++		return true;
++
++	sta = container_of(txq->sta, struct sta_info, sta);
++	if (atomic_read(&sta->airtime[txq->ac].aql_tx_pending) <
++	    sta->airtime[txq->ac].aql_limit_low)
++		return true;
++
++	if (atomic_read(&local->aql_total_pending_airtime) <
++	    local->aql_threshold &&
++	    atomic_read(&sta->airtime[txq->ac].aql_tx_pending) <
++	    sta->airtime[txq->ac].aql_limit_high)
++		return true;
++
++	return false;
++}
++EXPORT_SYMBOL(ieee80211_txq_airtime_check);
++
+ bool ieee80211_txq_may_transmit(struct ieee80211_hw *hw,
+ 				struct ieee80211_txq *txq)
+ {