mac80211: add rate control rewrite and enhance the performance of the minstrel algorithm for non-mrr configurations

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@12948 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 100 insertions, 0 deletions

diff --git a/package/mac80211/patches/426-minstrel_performance.patch b/package/mac80211/patches/426-minstrel_performance.patch
new file mode 100644
index 000000000..7b95163c6
--- /dev/null
+++ b/package/mac80211/patches/426-minstrel_performance.patch
@@ -0,0 +1,100 @@
+This patch enhances minstrel's performance for non-MRR setups,
+by preventing it from sampling slower rates with >95% success
+probability and by putting at least 1 non-sample frame between
+several sample frames.
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+
+--- a/net/mac80211/rc80211_minstrel.c
++++ b/net/mac80211/rc80211_minstrel.c
+@@ -126,7 +126,9 @@ minstrel_update_stats(struct minstrel_pr
+ 			mr->adjusted_retry_count = mr->retry_count >> 1;
+ 			if (mr->adjusted_retry_count > 2)
+ 				mr->adjusted_retry_count = 2;
++			mr->sample_limit = 4;
+ 		} else {
++			mr->sample_limit = -1;
+ 			mr->adjusted_retry_count = mr->retry_count;
+ 		}
+ 		if (!mr->adjusted_retry_count)
+@@ -265,7 +267,8 @@ minstrel_get_rate(void *priv, struct iee
+ 			(mi->sample_count + mi->sample_deferred / 2);
+ 
+ 	/* delta > 0: sampling required */
+-	if (delta > 0) {
++	if ((delta > 0) && (mrr || !mi->prev_sample)) {
++		struct minstrel_rate *msr;
+ 		if (mi->packet_count >= 10000) {
+ 			mi->sample_deferred = 0;
+ 			mi->sample_count = 0;
+@@ -284,13 +287,20 @@ minstrel_get_rate(void *priv, struct iee
+ 		}
+ 
+ 		sample_ndx = minstrel_get_next_sample(mi);
++		msr = &mi->r[sample_ndx];
+ 		sample = true;
+-		sample_slower = mrr && (mi->r[sample_ndx].perfect_tx_time >
++		sample_slower = mrr && (msr->perfect_tx_time >
+ 			mi->r[ndx].perfect_tx_time);
+ 
+ 		if (!sample_slower) {
+-			ndx = sample_ndx;
+-			mi->sample_count++;
++			if (msr->sample_limit != 0) {
++				ndx = sample_ndx;
++				mi->sample_count++;
++				if (msr->sample_limit > 0)
++					msr->sample_limit--;
++			} else {
++				sample = false;
++			}
+ 		} else {
+ 			/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
+ 			 * packets that have the sampling rate deferred to the
+@@ -302,10 +312,20 @@ minstrel_get_rate(void *priv, struct iee
+ 			mi->sample_deferred++;
+ 		}
+ 	}
++	mi->prev_sample = sample;
++
++	/* If we're not using MRR and the sampling rate already
++	 * has a probability of >95%, we shouldn't be attempting
++	 * to use it, as this only wastes precious airtime */
++	if (!mrr && sample && (mi->r[ndx].probability > 17100))
++		ndx = mi->max_tp_rate;
++
+ 	ar[0].idx = mi->r[ndx].rix;
+ 	ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);
+ 
+ 	if (!mrr) {
++		if (!sample)
++			ar[0].count = mp->max_retry;
+ 		ar[1].idx = mi->lowest_rix;
+ 		ar[1].count = mp->max_retry;
+ 		return;
+@@ -401,6 +421,7 @@ minstrel_rate_init(void *priv, struct ie
+ 
+ 		/* calculate maximum number of retransmissions before
+ 		 * fallback (based on maximum segment size) */
++		mr->sample_limit = -1;
+ 		mr->retry_count = 1;
+ 		mr->retry_count_cts = 1;
+ 		mr->retry_count_rtscts = 1;
+--- a/net/mac80211/rc80211_minstrel.h
++++ b/net/mac80211/rc80211_minstrel.h
+@@ -16,6 +16,7 @@ struct minstrel_rate {
+ 	unsigned int perfect_tx_time;
+ 	unsigned int ack_time;
+ 
++	int sample_limit;
+ 	unsigned int retry_count;
+ 	unsigned int retry_count_cts;
+ 	unsigned int retry_count_rtscts;
+@@ -57,6 +58,7 @@ struct minstrel_sta_info {
+ 
+ 	int n_rates;
+ 	struct minstrel_rate *r;
++	bool prev_sample;
+ 
+ 	/* sampling table */
+ 	u8 *sample_table;