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mac80211: minstrel_ht: improve sample rate skip logic

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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>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Felix Fietkau 2016-03-03 23:25:42 +01:00 committed by Johannes Berg
parent 07310a6314
commit 06171e9c0b
1 changed files with 16 additions and 7 deletions
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23
net/mac80211/rc80211_minstrel_ht.c
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@ -924,6 +924,7 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
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) {
@ -945,14 +946,22 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
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;
/*
@ -967,10 +976,10 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
* 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))) {