mac80211: add an improved moving average algorithm to minstrel

Improves rate control responsiveness and performance

Signed-off-by: Felix Fietkau <nbd@nbd.name>
[reworked to apply on 4.19.79 mac80211 + renumbered + refreshed]
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/subsys/362-mac80211-minstrel-remove-divisions-in-tx-status-path.patch b/package/kernel/mac80211/patches/subsys/362-mac80211-minstrel-remove-divisions-in-tx-status-path.patch
new file mode 100644
index 0000000000..d38d33b41e
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/362-mac80211-minstrel-remove-divisions-in-tx-status-path.patch
@@ -0,0 +1,61 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 28 Sep 2019 15:44:06 +0200
+Subject: [PATCH] mac80211: minstrel: remove divisions in tx status path
+
+Use a slightly different threshold for downgrading spatial streams to
+make it easier to calculate without divisions.
+Slightly reduces CPU overhead.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/rc80211_minstrel.c
++++ b/net/mac80211/rc80211_minstrel.c
+@@ -295,8 +295,7 @@ minstrel_tx_status(void *priv, struct ie
+ 	if (mi->sample_deferred > 0)
+ 		mi->sample_deferred--;
+ 
+-	if (time_after(jiffies, mi->last_stats_update +
+-				(mp->update_interval * HZ) / 1000))
++	if (time_after(jiffies, mi->last_stats_update + mp->update_interval))
+ 		minstrel_update_stats(mp, mi);
+ }
+ 
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -937,23 +937,21 @@ minstrel_ht_tx_status(void *priv, struct
+ 		 */
+ 		rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
+ 		if (rate->attempts > 30 &&
+-		    MINSTREL_FRAC(rate->success, rate->attempts) <
+-		    MINSTREL_FRAC(20, 100)) {
++		    rate->success < rate->attempts / 4) {
+ 			minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
+ 			update = true;
+ 		}
+ 
+ 		rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
+ 		if (rate2->attempts > 30 &&
+-		    MINSTREL_FRAC(rate2->success, rate2->attempts) <
+-		    MINSTREL_FRAC(20, 100)) {
++		    rate2->success < rate2->attempts / 4) {
+ 			minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
+ 			update = true;
+ 		}
+ 	}
+ 
+ 	if (time_after(jiffies, mi->last_stats_update +
+-				(mp->update_interval / 2 * HZ) / 1000)) {
++				mp->update_interval / 2)) {
+ 		update = true;
+ 		minstrel_ht_update_stats(mp, mi, true);
+ 	}
+@@ -1640,7 +1638,7 @@ minstrel_ht_alloc(struct ieee80211_hw *h
+ 		mp->has_mrr = true;
+ 
+ 	mp->hw = hw;
+-	mp->update_interval = 100;
++	mp->update_interval = HZ / 10;
+ 
+ #ifdef CPTCFG_MAC80211_DEBUGFS
+ 	mp->fixed_rate_idx = (u32) -1;