mac80211: Dynamically set CoDel parameters per station

CoDel can be too aggressive if a station sends at a very low rate,
leading reduced throughput. This gets worse the more stations are
present, as each station gets more bursty the longer the round-robin
scheduling between stations takes.

This adds dynamic adjustment of CoDel parameters per station. It uses
the rate selection information to estimate throughput and sets more
lenient CoDel parameters if the estimated throughput is below a
threshold (modified by the number of active stations).

A new callback is added that drivers can use to notify mac80211 about
changes in expected throughput, so the same adjustment can be made for
cards that implement rate control in firmware. Drivers that don't use
this will just get the default parameters.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
[remove currently unnecessary EXPORT_SYMBOL, fix kernel-doc, remove
inline annotation]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 7cdf7a835bb0..f59434ac385d 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -20,6 +20,7 @@
 #include <linux/timer.h>
 #include <linux/rtnetlink.h>
 
+#include <net/codel.h>
 #include <net/mac80211.h>
 #include "ieee80211_i.h"
 #include "driver-ops.h"
@@ -425,6 +426,11 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 
 	sta->sta.max_rc_amsdu_len = IEEE80211_MAX_MPDU_LEN_HT_BA;
 
+	sta->cparams.ce_threshold = CODEL_DISABLED_THRESHOLD;
+	sta->cparams.target = MS2TIME(20);
+	sta->cparams.interval = MS2TIME(100);
+	sta->cparams.ecn = true;
+
 	sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);
 
 	return sta;
@@ -2310,3 +2316,27 @@ unsigned long ieee80211_sta_last_active(struct sta_info *sta)
 		return stats->last_rx;
 	return sta->status_stats.last_ack;
 }
+
+static void sta_update_codel_params(struct sta_info *sta, u32 thr)
+{
+	if (!sta->sdata->local->ops->wake_tx_queue)
+		return;
+
+	if (thr && thr < STA_SLOW_THRESHOLD * sta->local->num_sta) {
+		sta->cparams.target = MS2TIME(50);
+		sta->cparams.interval = MS2TIME(300);
+		sta->cparams.ecn = false;
+	} else {
+		sta->cparams.target = MS2TIME(20);
+		sta->cparams.interval = MS2TIME(100);
+		sta->cparams.ecn = true;
+	}
+}
+
+void ieee80211_sta_set_expected_throughput(struct ieee80211_sta *pubsta,
+					   u32 thr)
+{
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+
+	sta_update_codel_params(sta, thr);
+}