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mac80211: simplify minstrel_ht code, rewrite packet sampling algorithm for improved performance and a-mpdu length

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git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20035 3c298f89-4303-0410-b956-a3cf2f4a3e73
This commit is contained in:
nbd 2010-03-07 16:29:41 +00:00
parent fa28364d93
commit 1af59a69e7
1 changed files with 107 additions and 126 deletions
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233
package/mac80211/patches/560-minstrel_ht.patch
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@ -68,7 +68,7 @@
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -0,0 +1,824 @@
@@ -0,0 +1,800 @@
+/*
+ * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
+ *
@ -125,9 +125,6 @@
+ } \
+}
+
+#define MINSTREL_INTFL_SAMPLE_SLOT0 BIT(30)
+#define MINSTREL_INTFL_SAMPLE_SLOT1 BIT(31)
+
+/*
+ * To enable sufficiently targeted rate sampling, MCS rates are divided into
+ * groups, based on the number of streams and flags (HT40, SGI) that they
@ -206,7 +203,8 @@
+static void
+minstrel_calc_rate_ewma(struct minstrel_priv *mp, struct minstrel_rate_stats *mr)
+{
+ if (mr->attempts) {
+ if (unlikely(mr->attempts > 0)) {
+ mr->sample_skipped = 0;
+ mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
+ if (!mr->att_hist)
+ mr->probability = mr->cur_prob;
@ -215,6 +213,8 @@
+ mr->cur_prob, EWMA_LEVEL);
+ mr->att_hist += mr->attempts;
+ mr->succ_hist += mr->success;
+ } else {
+ mr->sample_skipped++;
+ }
+ mr->last_success = mr->success;
+ mr->last_attempts = mr->attempts;
@ -262,6 +262,7 @@
+ int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
+ int group, i, index;
+
+ mi->sample_count = 0;
+ mi->max_tp_rate = 0;
+ mi->max_tp_rate2 = 0;
+ mi->max_prob_rate = 0;
@ -279,6 +280,7 @@
+ mg->max_tp_rate = 0;
+ mg->max_tp_rate2 = 0;
+ mg->max_prob_rate = 0;
+ mi->sample_count++;
+
+ for (i = 0; i < MCS_GROUP_RATES; i++) {
+ if (!(mg->supported & BIT(i)))
@ -309,7 +311,7 @@
+ mr = minstrel_get_ratestats(mi, index);
+ }
+
+ if (index == mg->max_tp_rate)
+ if (index >= mg->max_tp_rate)
+ continue;
+
+ if (mr->cur_tp > cur_tp2) {
@ -319,6 +321,9 @@
+ }
+ }
+
+ /* try to sample up to half of the availble rates during each interval */
+ mi->sample_count *= 4;
+
+ cur_prob = 0;
+ cur_prob_tp = 0;
+ cur_tp = 0;
@ -386,7 +391,7 @@
+}
+
+static void
+minstrel_downgrade_rate(struct minstrel_ht_sta *mi, int *idx, int type)
+minstrel_downgrade_rate(struct minstrel_ht_sta *mi, int *idx, bool primary)
+{
+ int group, orig_group;
+
@ -397,18 +402,14 @@
+ if (!mi->groups[group].supported)
+ continue;
+
+ if (minstrel_mcs_groups[group].streams >=
+ if (minstrel_mcs_groups[group].streams >
+ minstrel_mcs_groups[orig_group].streams)
+ continue;
+
+ switch(type) {
+ case 0:
+ if (primary)
+ *idx = mi->groups[group].max_tp_rate;
+ break;
+ case 1:
+ else
+ *idx = mi->groups[group].max_tp_rate2;
+ break;
+ }
+ break;
+ }
+}
@ -445,6 +446,17 @@
+ mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
+ MINSTREL_FRAC(info->status.ampdu_len, 1), 90);
+
+ if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
+ mi->sample_wait = 4 + MINSTREL_TRUNC(mi->avg_ampdu_len);
+ mi->sample_tries = 3;
+ mi->sample_count--;
+ }
+
+ if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) {
+ mi->sample_packets += info->status.ampdu_len;
+ minstrel_next_sample_idx(mi);
+ }
+
+ for (i = 0; !last; i++) {
+ last = (i == IEEE80211_TX_MAX_RATES - 1) ||
+ !minstrel_ht_txstat_valid(&ar[i + 1]);
@ -452,14 +464,6 @@
+ if (!minstrel_ht_txstat_valid(&ar[i]))
+ break;
+
+ if ((i == 0 && (info->flags & MINSTREL_INTFL_SAMPLE_SLOT0)) ||
+ (i == 1 && (info->flags & MINSTREL_INTFL_SAMPLE_SLOT1))) {
+ if (mi->sample_pending > 0)
+ mi->sample_pending--;
+ mi->sample_packets++;
+ minstrel_next_sample_idx(mi);
+ }
+
+ group = minstrel_ht_get_group_idx(&ar[i]);
+ rate = &mi->groups[group].rates[ar[i].idx % 8];
+
@ -469,20 +473,19 @@
+ rate->attempts += ar[i].count * info->status.ampdu_len;
+ }
+
+
+ /*
+ * check for sudden death of spatial multiplexing,
+ * downgrade to a lower number of streams if necessary.
+ */
+ rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
+ if (MINSTREL_FRAC(rate->success, rate->attempts) <
+ MINSTREL_FRAC(20, 100) && rate->attempts > 15)
+ minstrel_downgrade_rate(mi, &mi->max_tp_rate, 0);
+ MINSTREL_FRAC(20, 100) && rate->attempts > 30)
+ minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
+
+ rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
+ if (MINSTREL_FRAC(rate->success, rate->attempts) <
+ MINSTREL_FRAC(20, 100) && rate->attempts > 15)
+ minstrel_downgrade_rate(mi, &mi->max_tp_rate2, 1);
+ MINSTREL_FRAC(20, 100) && rate->attempts > 30)
+ minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
+
+ if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000))
+ minstrel_ht_update_stats(mp, mi);
@ -560,41 +563,21 @@
+}
+
+static int
+minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+ bool *defer)
+minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
+{
+ struct minstrel_rate_stats *mr;
+ struct minstrel_mcs_group_data *mg;
+ int sample_idx = 0;
+ int sample_rate;
+ int delta;
+
+ if (mp->has_mrr)
+ sample_rate = mp->lookaround_rate_mrr;
+ else
+ sample_rate = mp->lookaround_rate;
+
+ delta = (mi->total_packets * sample_rate) / 100 - mi->sample_packets;
+ delta -= mi->sample_pending / 2;
+
+ if (delta <= 0)
+ if (mi->sample_wait > 0) {
+ mi->sample_wait--;
+ return -1;
+
+ delta -= 16;
+ if (delta > 1) {
+ /* With multi-rate retry, not every planned sample
+ * attempt actually gets used, due to the way the retry
+ * chain is set up - [max_tp,sample,prob,lowest] for
+ * sample_rate < max_tp.
+ *
+ * If there's too much sampling backlog and the link
+ * starts getting worse, minstrel would start bursting
+ * out lots of sampling frames, which would result
+ * in a large throughput loss.
+ */
+ mi->sample_packets += delta - 1;
+ }
+
+ if (!mi->sample_tries)
+ return -1;
+
+ mi->sample_tries--;
+ mg = &mi->groups[mi->sample_group];
+ sample_idx = sample_table[mg->column][mg->index];
+ mr = &mg->rates[sample_idx];
@ -605,27 +588,22 @@
+ * higher than 95% to avoid wasting airtime
+ */
+ if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
+ return -1;
+ goto next;
+
+ /*
+ * Make sure that lower rates get sampled only occasionally,
+ * if the link is working perfectly.
+ */
+ if (minstrel_get_duration(sample_idx) >
+ minstrel_get_duration(mi->max_tp_rate)) {
+ /*
+ * Make sure that lower rates get sampled occasionally, even
+ * if the link is working perfectly. Some drivers such as ath9k
+ * severely limit aggregation size if the MRR chain contains low
+ * rates
+ *
+ * If the lower rate has already been tried a few times, there's
+ * no point in forcing it to be sampled again, so skip to the
+ * next sampling index after applying this one in the tx control
+ */
+ if (mr->att_hist > 15) {
+ *defer = true;
+ minstrel_next_sample_idx(mi);
+ }
+ }
+ minstrel_get_duration(mi->max_tp_rate) &&
+ mr->sample_skipped < 10)
+ goto next;
+
+ return sample_idx;
+
+next:
+ minstrel_next_sample_idx(mi);
+ return -1;
+}
+
+static void
@ -657,7 +635,6 @@
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+ struct minstrel_ht_sta *mi = &msp->ht;
+ struct minstrel_priv *mp = priv;
+ bool sample_defer = false;
+ int sample_idx;
+
+ if (rate_control_send_low(sta, priv_sta, txrc))
@ -668,22 +645,13 @@
+
+ minstrel_aggr_check(mp, sta, txrc->skb);
+
+ sample_idx = minstrel_get_sample_rate(mp, mi, &sample_defer);
+ sample_idx = minstrel_get_sample_rate(mp, mi);
+ if (sample_idx >= 0) {
+ if (sample_defer) {
+ minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
+ txrc, false, false);
+ minstrel_ht_set_rate(mp, mi, &ar[1], sample_idx,
+ txrc, true, true);
+ info->flags |= MINSTREL_INTFL_SAMPLE_SLOT1;
+ } else {
+ minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
+ txrc, true, false);
+ minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
+ txrc, false, true);
+ info->flags |= MINSTREL_INTFL_SAMPLE_SLOT0;
+ }
+ mi->sample_pending++;
+ minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
+ txrc, true, false);
+ minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
+ txrc, false, true);
+ info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
+ } else {
+ minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
+ txrc, false, false);
@ -698,21 +666,58 @@
+ mi->total_packets++;
+
+ /* wraparound */
+ if (mi->total_packets >= 100000) {
+ if (mi->total_packets == ~0) {
+ mi->total_packets = 0;
+ mi->sample_packets = 0;
+ mi->sample_pending = 0;
+ }
+}
+
+static void
+minstrel_ht_update_cap(struct minstrel_ht_sta *mi, struct ieee80211_sta *sta,
+ enum nl80211_channel_type oper_chan_type)
+minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
+ struct ieee80211_sta *sta, void *priv_sta,
+ enum nl80211_channel_type oper_chan_type)
+{
+ struct minstrel_priv *mp = priv;
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+ struct minstrel_ht_sta *mi = &msp->ht;
+ struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
+ struct ieee80211_local *local = hw_to_local(mp->hw);
+ u16 sta_cap = sta->ht_cap.cap;
+ int ack_dur;
+ int i;
+
+ /* fall back to the old minstrel for legacy stations */
+ if (sta && !sta->ht_cap.ht_supported) {
+ msp->is_ht = false;
+ memset(&msp->legacy, 0, sizeof(msp->legacy));
+ msp->legacy.r = msp->ratelist;
+ msp->legacy.sample_table = msp->sample_table;
+ return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
+ }
+
+ BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
+ MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
+
+ msp->is_ht = true;
+ memset(mi, 0, sizeof(*mi));
+ mi->stats_update = jiffies;
+
+ ack_dur = ieee80211_frame_duration(local, 10, 60, 1, 1);
+ mi->overhead = ieee80211_frame_duration(local, 0, 60, 1, 1) + ack_dur;
+ mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
+
+ mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
+
+ /* When using MRR, sample more on the first attempt, without delay */
+ if (mp->has_mrr) {
+ mi->sample_count = 16;
+ mi->sample_wait = 0;
+ } else {
+ mi->sample_count = 8;
+ mi->sample_wait = 8;
+ }
+ mi->sample_tries = 4;
+
+ if (oper_chan_type != NL80211_CHAN_HT40MINUS &&
+ oper_chan_type != NL80211_CHAN_HT40PLUS)
+ sta_cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
@ -744,34 +749,8 @@
+ struct ieee80211_sta *sta, void *priv_sta)
+{
+ struct minstrel_priv *mp = priv;
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+ struct minstrel_ht_sta *mi = &msp->ht;
+ struct ieee80211_local *local = hw_to_local(mp->hw);
+ int ack_dur;
+
+ /* fall back to the old minstrel for legacy stations */
+ if (sta && !sta->ht_cap.ht_supported) {
+ msp->is_ht = false;
+ memset(&msp->legacy, 0, sizeof(msp->legacy));
+ msp->legacy.r = msp->ratelist;
+ msp->legacy.sample_table = msp->sample_table;
+ return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
+ }
+
+ BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
+ MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
+
+ msp->is_ht = true;
+ memset(mi, 0, sizeof(*mi));
+ mi->stats_update = jiffies;
+
+ ack_dur = ieee80211_frame_duration(local, 10, 60, 1, 1);
+ mi->overhead = ieee80211_frame_duration(local, 0, 60, 1, 1) + ack_dur;
+ mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
+
+ mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
+
+ minstrel_ht_update_cap(mi, sta, mp->hw->conf.channel_type);
+ minstrel_ht_update_caps(priv, sband, sta, priv_sta, mp->hw->conf.channel_type);
+}
+
+static void
@ -779,10 +758,7 @@
+ struct ieee80211_sta *sta, void *priv_sta,
+ u32 changed, enum nl80211_channel_type oper_chan_type)
+{
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+ struct minstrel_ht_sta *mi = &msp->ht;
+
+ minstrel_ht_update_cap(mi, sta, oper_chan_type);
+ minstrel_ht_update_caps(priv, sband, sta, priv_sta, oper_chan_type);
+}
+
+static void *
@ -895,7 +871,7 @@
+}
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -0,0 +1,115 @@
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
+ *
@ -942,9 +918,11 @@
+ unsigned int cur_prob, probability;
+
+ /* maximum retry counts */
+ bool retry_updated;
+ unsigned int retry_count;
+ unsigned int retry_count_rtscts;
+
+ bool retry_updated;
+ u8 sample_skipped;
+};
+
+struct minstrel_mcs_group_data {
@ -985,10 +963,13 @@
+
+ unsigned int total_packets;
+ unsigned int sample_packets;
+ unsigned int sample_pending;
+
+ u8 sample_wait;
+ u8 sample_tries;
+ u8 sample_count;
+
+ /* current MCS group to be sampled */
+ unsigned int sample_group;
+ u8 sample_group;
+
+ /* MCS rate group info and statistics */
+ struct minstrel_mcs_group_data groups[MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS];