minstrel: improve performance for non-MRR drivers
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>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
index 759ddd8..c10debc 100644
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -126,7 +126,9 @@
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 @@
(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 @@
}
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 @@
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 @@
/* 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;
diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h
index 9a90a6a..869fe0e 100644
--- a/net/mac80211/rc80211_minstrel.h
+++ b/net/mac80211/rc80211_minstrel.h
@@ -16,6 +16,7 @@
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 @@
int n_rates;
struct minstrel_rate *r;
+ bool prev_sample;
/* sampling table */
u8 *sample_table;