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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))) {
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