mac80211: add minstrel performance improvements
[openwrt/openwrt.git] / package / kernel / mac80211 / patches / subsys / 355-mac80211-minstrel_ht-rework-rate-downgrade-code-and-.patch
1 From: Felix Fietkau <nbd@nbd.name>
2 Date: Sat, 6 Feb 2021 16:33:14 +0100
3 Subject: [PATCH] mac80211: minstrel_ht: rework rate downgrade code and
4 max_prob rate selection
5
6 The current fallback code for fast rate switching on potentially failing rates
7 is triggering too often if there is some strong noise on the channel. This can
8 lead to wild fluctuations in the rate selection.
9 Additionally, switching down to max_prob_rate can create a significant gap down
10 in throughput, especially when using only 2 spatial streams, because max_prob_rate
11 is limited to using fewer streams than the max_tp rates.
12 In order to improve throughput without reducing reliability too much, use the
13 rate downgrade code for the max_prob_rate only, and allow the non-downgraded
14 max_prob_rate to use as many spatial streams as the max_tp rates
15
16 Signed-off-by: Felix Fietkau <nbd@nbd.name>
17 ---
18
19 --- a/net/mac80211/rc80211_minstrel_ht.c
20 +++ b/net/mac80211/rc80211_minstrel_ht.c
21 @@ -511,6 +511,14 @@ minstrel_ht_set_best_prob_rate(struct mi
22 int cur_tp_avg, cur_group, cur_idx;
23 int max_gpr_group, max_gpr_idx;
24 int max_gpr_tp_avg, max_gpr_prob;
25 + int min_dur;
26 +
27 + min_dur = max(minstrel_get_duration(mi->max_tp_rate[0]),
28 + minstrel_get_duration(mi->max_tp_rate[1]));
29 +
30 + /* make the rate at least 18% slower than max tp rates */
31 + if (minstrel_get_duration(index) <= min_dur * 19 / 16)
32 + return;
33
34 cur_group = MI_RATE_GROUP(index);
35 cur_idx = MI_RATE_IDX(index);
36 @@ -532,11 +540,6 @@ minstrel_ht_set_best_prob_rate(struct mi
37 !minstrel_ht_is_legacy_group(max_tp_group))
38 return;
39
40 - /* skip rates faster than max tp rate with lower prob */
41 - if (minstrel_get_duration(mi->max_tp_rate[0]) > minstrel_get_duration(index) &&
42 - mrs->prob_avg < max_tp_prob)
43 - return;
44 -
45 max_gpr_group = MI_RATE_GROUP(mg->max_group_prob_rate);
46 max_gpr_idx = MI_RATE_IDX(mg->max_group_prob_rate);
47 max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_avg;
48 @@ -594,40 +597,6 @@ minstrel_ht_assign_best_tp_rates(struct
49
50 }
51
52 -/*
53 - * Try to increase robustness of max_prob rate by decrease number of
54 - * streams if possible.
55 - */
56 -static inline void
57 -minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
58 -{
59 - struct minstrel_mcs_group_data *mg;
60 - int tmp_max_streams, group, tmp_idx, tmp_prob;
61 - int tmp_tp = 0;
62 -
63 - if (!mi->sta->ht_cap.ht_supported)
64 - return;
65 -
66 - group = MI_RATE_GROUP(mi->max_tp_rate[0]);
67 - tmp_max_streams = minstrel_mcs_groups[group].streams;
68 - for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
69 - mg = &mi->groups[group];
70 - if (!mi->supported[group] || group == MINSTREL_CCK_GROUP)
71 - continue;
72 -
73 - tmp_idx = MI_RATE_IDX(mg->max_group_prob_rate);
74 - tmp_prob = mi->groups[group].rates[tmp_idx].prob_avg;
75 -
76 - if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
77 - (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
78 - mi->max_prob_rate = mg->max_group_prob_rate;
79 - tmp_tp = minstrel_ht_get_tp_avg(mi, group,
80 - tmp_idx,
81 - tmp_prob);
82 - }
83 - }
84 -}
85 -
86 static u16
87 __minstrel_ht_get_sample_rate(struct minstrel_ht_sta *mi,
88 enum minstrel_sample_type type)
89 @@ -1111,8 +1080,6 @@ minstrel_ht_update_stats(struct minstrel
90
91 mi->max_prob_rate = tmp_max_prob_rate;
92
93 - /* Try to increase robustness of max_prob_rate*/
94 - minstrel_ht_prob_rate_reduce_streams(mi);
95 minstrel_ht_refill_sample_rates(mi);
96
97 #ifdef CPTCFG_MAC80211_DEBUGFS
98 @@ -1157,7 +1124,7 @@ minstrel_ht_txstat_valid(struct minstrel
99 }
100
101 static void
102 -minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
103 +minstrel_downgrade_prob_rate(struct minstrel_ht_sta *mi, u16 *idx)
104 {
105 int group, orig_group;
106
107 @@ -1172,11 +1139,7 @@ minstrel_downgrade_rate(struct minstrel_
108 minstrel_mcs_groups[orig_group].streams)
109 continue;
110
111 - if (primary)
112 - *idx = mi->groups[group].max_group_tp_rate[0];
113 - else
114 - *idx = mi->groups[group].max_group_tp_rate[1];
115 - break;
116 + *idx = mi->groups[group].max_group_prob_rate;
117 }
118 }
119
120 @@ -1210,7 +1173,7 @@ minstrel_ht_tx_status(void *priv, struct
121 struct ieee80211_tx_info *info = st->info;
122 struct minstrel_ht_sta *mi = priv_sta;
123 struct ieee80211_tx_rate *ar = info->status.rates;
124 - struct minstrel_rate_stats *rate, *rate2;
125 + struct minstrel_rate_stats *rate;
126 struct minstrel_priv *mp = priv;
127 u32 update_interval = mp->update_interval;
128 bool last, update = false;
129 @@ -1256,18 +1219,13 @@ minstrel_ht_tx_status(void *priv, struct
130 /*
131 * check for sudden death of spatial multiplexing,
132 * downgrade to a lower number of streams if necessary.
133 + * only do this for the max_prob_rate to prevent spurious
134 + * rate fluctuations when the link changes suddenly
135 */
136 - rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
137 + rate = minstrel_get_ratestats(mi, mi->max_prob_rate);
138 if (rate->attempts > 30 &&
139 rate->success < rate->attempts / 4) {
140 - minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
141 - update = true;
142 - }
143 -
144 - rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
145 - if (rate2->attempts > 30 &&
146 - rate2->success < rate2->attempts / 4) {
147 - minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
148 + minstrel_downgrade_prob_rate(mi, &mi->max_prob_rate);
149 update = true;
150 }
151 }