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-rw-r--r--package/kernel/mac80211/patches/343-mac80211-minstrel_ht-improve-sample-rate-skip-logic.patch77
1 files changed, 77 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/343-mac80211-minstrel_ht-improve-sample-rate-skip-logic.patch b/package/kernel/mac80211/patches/343-mac80211-minstrel_ht-improve-sample-rate-skip-logic.patch
new file mode 100644
index 0000000000..55ff817009
--- /dev/null
+++ b/package/kernel/mac80211/patches/343-mac80211-minstrel_ht-improve-sample-rate-skip-logic.patch
@@ -0,0 +1,77 @@
+From: Felix Fietkau <nbd@openwrt.org>
+Date: Thu, 3 Mar 2016 23:20:06 +0100
+Subject: [PATCH] mac80211: minstrel_ht: improve sample rate skip logic
+
+There were a few issues that were slowing down the process of finding
+the optimal rate, especially on devices with multi-rate retry
+limitations:
+
+When max_tp_rate[0] was slower than max_tp_rate[1], the code did not
+sample max_tp_rate[1], which would often allow it to switch places with
+max_tp_rate[0] (e.g. if only the first sampling attempts were bad, but the
+rate is otherwise good).
+
+Also, sample attempts of rates between max_tp_rate[0] and [1] were being
+ignored in this case, because the code only checked if the rate was
+slower than [1].
+
+Fix this by checking against the fastest / second fastest max_tp_rate
+instead of assuming a specific order between the two.
+
+In my tests this patch significantly reduces the time until minstrel_ht
+finds the optimal rate right after assoc
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+---
+
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -958,6 +958,7 @@ minstrel_get_sample_rate(struct minstrel
+ struct minstrel_rate_stats *mrs;
+ struct minstrel_mcs_group_data *mg;
+ unsigned int sample_dur, sample_group, cur_max_tp_streams;
++ int tp_rate1, tp_rate2;
+ int sample_idx = 0;
+
+ if (mi->sample_wait > 0) {
+@@ -979,14 +980,22 @@ minstrel_get_sample_rate(struct minstrel
+ mrs = &mg->rates[sample_idx];
+ sample_idx += sample_group * MCS_GROUP_RATES;
+
++ /* Set tp_rate1, tp_rate2 to the highest / second highest max_tp_rate */
++ if (minstrel_get_duration(mi->max_tp_rate[0]) >
++ minstrel_get_duration(mi->max_tp_rate[1])) {
++ tp_rate1 = mi->max_tp_rate[1];
++ tp_rate2 = mi->max_tp_rate[0];
++ } else {
++ tp_rate1 = mi->max_tp_rate[0];
++ tp_rate2 = mi->max_tp_rate[1];
++ }
++
+ /*
+ * Sampling might add some overhead (RTS, no aggregation)
+- * to the frame. Hence, don't use sampling for the currently
+- * used rates.
++ * to the frame. Hence, don't use sampling for the highest currently
++ * used highest throughput or probability rate.
+ */
+- if (sample_idx == mi->max_tp_rate[0] ||
+- sample_idx == mi->max_tp_rate[1] ||
+- sample_idx == mi->max_prob_rate)
++ if (sample_idx == mi->max_tp_rate[0] || sample_idx == mi->max_prob_rate)
+ return -1;
+
+ /*
+@@ -1001,10 +1010,10 @@ minstrel_get_sample_rate(struct minstrel
+ * if the link is working perfectly.
+ */
+
+- cur_max_tp_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
++ cur_max_tp_streams = minstrel_mcs_groups[tp_rate1 /
+ MCS_GROUP_RATES].streams;
+ sample_dur = minstrel_get_duration(sample_idx);
+- if (sample_dur >= minstrel_get_duration(mi->max_tp_rate[1]) &&
++ if (sample_dur >= minstrel_get_duration(tp_rate2) &&
+ (cur_max_tp_streams - 1 <
+ minstrel_mcs_groups[sample_group].streams ||
+ sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {