Hi again,
here is an updated version of my minstrel_ht code. Since the last
version, I've added the following improvements:
- Use accurate A-MPDU statistics from tx feedback
- Rewrite the sampling algorithm to optimize for good A-MPDU lengths
and faster throughput recovery
- Implement .rate_update to handle changes in HT capabilities or
channel bandwidth
- Remove the private tx flags hack
With the new version, performance has improved visibly for HT40 in all
of my tests. I think it's getting closer to being ready for inclusion.
---
--- a/net/mac80211/Makefile
+++ b/net/mac80211/Makefile
@@ -47,8 +47,8 @@ CFLAGS_driver-trace.o := -I$(src)
rc80211_pid-y := rc80211_pid_algo.o
rc80211_pid-$(CONFIG_MAC80211_DEBUGFS) += rc80211_pid_debugfs.o
-rc80211_minstrel-y := rc80211_minstrel.o
-rc80211_minstrel-$(CONFIG_MAC80211_DEBUGFS) += rc80211_minstrel_debugfs.o
+rc80211_minstrel-y := rc80211_minstrel.o rc80211_minstrel_ht.o
+rc80211_minstrel-$(CONFIG_MAC80211_DEBUGFS) += rc80211_minstrel_debugfs.o rc80211_minstrel_ht_debugfs.o
mac80211-$(CONFIG_MAC80211_RC_PID) += $(rc80211_pid-y)
mac80211-$(CONFIG_MAC80211_RC_MINSTREL) += $(rc80211_minstrel-y)
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -714,6 +714,10 @@ static int __init ieee80211_init(void)
if (ret)
return ret;
+ ret = rc80211_minstrel_ht_init();
+ if (ret)
+ goto err_minstrel;
+
ret = rc80211_pid_init();
if (ret)
goto err_pid;
@@ -726,6 +730,8 @@ static int __init ieee80211_init(void)
err_netdev:
rc80211_pid_exit();
err_pid:
+ rc80211_minstrel_ht_exit();
+ err_minstrel:
rc80211_minstrel_exit();
return ret;
@@ -734,6 +740,7 @@ static int __init ieee80211_init(void)
static void __exit ieee80211_exit(void)
{
rc80211_pid_exit();
+ rc80211_minstrel_ht_exit();
rc80211_minstrel_exit();
/*
--- a/net/mac80211/rate.h
+++ b/net/mac80211/rate.h
@@ -137,6 +137,8 @@ static inline void rc80211_pid_exit(void
#ifdef CONFIG_MAC80211_RC_MINSTREL
extern int rc80211_minstrel_init(void);
extern void rc80211_minstrel_exit(void);
+extern int rc80211_minstrel_ht_init(void);
+extern void rc80211_minstrel_ht_exit(void);
#else
static inline int rc80211_minstrel_init(void)
{
@@ -145,6 +147,13 @@ static inline int rc80211_minstrel_init(
static inline void rc80211_minstrel_exit(void)
{
}
+static inline int rc80211_minstrel_ht_init(void)
+{
+ return 0;
+}
+static inline void rc80211_minstrel_ht_exit(void)
+{
+}
#endif
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -0,0 +1,800 @@
+/*
+ * Copyright (C) 2010 Felix Fietkau <nbd@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/debugfs.h>
+#include <linux/random.h>
+#include <linux/ieee80211.h>
+#include <net/mac80211.h>
+#include "rate.h"
+#include "rc80211_minstrel.h"
+#include "rc80211_minstrel_ht.h"
+
+#define AVG_PKT_SIZE 1200
+#define SAMPLE_COLUMNS 10
+#define EWMA_LEVEL 75
+
+/* Number of bits for an average sized packet */
+#define MCS_NBITS (AVG_PKT_SIZE << 3)
+
+/* Number of symbols for a packet with (bps) bits per symbol */
+#define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
+
+/* Transmission time for a packet containing (syms) symbols */
+#define MCS_SYMBOL_TIME(sgi, syms) \
+ (sgi ? \
+ ((syms) * 18 + 4) / 5 : /* syms * 3.6 us */ \
+ (syms) << 2 /* syms * 4 us */ \
+ )
+
+/* Transmit duration for the raw data part of an average sized packet */
+#define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
+
+/* MCS rate information for an MCS group */
+#define MCS_GROUP(_streams, _sgi, _ht40) { \
+ .streams = _streams, \
+ .flags = \
+ (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
+ (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
+ .duration = { \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \
+ MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \
+ } \
+}
+
+/*
+ * To enable sufficiently targeted rate sampling, MCS rates are divided into
+ * groups, based on the number of streams and flags (HT40, SGI) that they
+ * use.
+ */
+const struct mcs_group minstrel_mcs_groups[] = {
+ MCS_GROUP(1, 0, 0),
+ MCS_GROUP(2, 0, 0),
+#if MINSTREL_MAX_STREAMS >= 3
+ MCS_GROUP(3, 0, 0),
+#endif
+
+ MCS_GROUP(1, 1, 0),
+ MCS_GROUP(2, 1, 0),
+#if MINSTREL_MAX_STREAMS >= 3
+ MCS_GROUP(3, 1, 0),
+#endif
+
+ MCS_GROUP(1, 0, 1),
+ MCS_GROUP(2, 0, 1),
+#if MINSTREL_MAX_STREAMS >= 3
+ MCS_GROUP(3, 0, 1),
+#endif
+
+ MCS_GROUP(1, 1, 1),
+ MCS_GROUP(2, 1, 1),
+#if MINSTREL_MAX_STREAMS >= 3
+ MCS_GROUP(3, 1, 1),
+#endif
+};
+
+static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
+
+/*
+ * Perform EWMA (Exponentially Weighted Moving Average) calculation
+ */
+static int
+minstrel_ewma(int old, int new, int weight)
+{
+ return (new * (100 - weight) + old * weight) / 100;
+}
+
+/*
+ * Look up an MCS group index based on mac80211 rate information
+ */
+static int
+minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
+{
+ int streams = (rate->idx / MCS_GROUP_RATES) + 1;
+ u32 flags = IEEE80211_TX_RC_SHORT_GI | IEEE80211_TX_RC_40_MHZ_WIDTH;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
+ if (minstrel_mcs_groups[i].streams != streams)
+ continue;
+ if (minstrel_mcs_groups[i].flags != (rate->flags & flags))
+ continue;
+
+ return i;
+ }
+
+ WARN_ON(1);
+ return 0;
+}
+
+static inline struct minstrel_rate_stats *
+minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
+{
+ return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
+}
+
+
+/*
+ * Recalculate success probabilities and counters for a rate using EWMA
+ */
+static void
+minstrel_calc_rate_ewma(struct minstrel_priv *mp, struct minstrel_rate_stats *mr)
+{
+ 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;
+ else
+ mr->probability = minstrel_ewma(mr->probability,
+ 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;
+ mr->success = 0;
+ mr->attempts = 0;
+}
+
+/*
+ * Calculate throughput based on the average A-MPDU length, taking into account
+ * the expected number of retransmissions and their expected length
+ */
+static void
+minstrel_ht_calc_tp(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+ int group, int rate)
+{
+ struct minstrel_rate_stats *mr;
+ unsigned int usecs;
+
+ mr = &mi->groups[group].rates[rate];
+
+ if (mr->probability < MINSTREL_FRAC(1, 10)) {
+ mr->cur_tp = 0;
+ return;
+ }
+
+ usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
+ usecs += minstrel_mcs_groups[group].duration[rate];
+ mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
+}
+
+/*
+ * Update rate statistics and select new primary rates
+ *
+ * Rules for rate selection:
+ * - max_prob_rate must use only one stream, as a tradeoff between delivery
+ * probability and throughput during strong fluctuations
+ * - as long as the max prob rate has a probability of more than 3/4, pick
+ * higher throughput rates, even if the probablity is a bit lower
+ */
+static void
+minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
+{
+ struct minstrel_mcs_group_data *mg;
+ struct minstrel_rate_stats *mr;
+ 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;
+
+ for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
+ cur_prob = 0;
+ cur_prob_tp = 0;
+ cur_tp = 0;
+ cur_tp2 = 0;
+
+ mg = &mi->groups[group];
+ if (!mg->supported)
+ continue;
+
+ 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)))
+ continue;
+
+ mr = &mg->rates[i];
+ mr->retry_updated = false;
+ index = MCS_GROUP_RATES * group + i;
+ minstrel_calc_rate_ewma(mp, mr);
+ minstrel_ht_calc_tp(mp, mi, group, i);
+
+ if (!mr->cur_tp)
+ continue;
+
+ /* ignore the lowest rate of each single-stream group */
+ if (!i && minstrel_mcs_groups[group].streams == 1)
+ continue;
+
+ if ((mr->cur_tp > cur_prob_tp && mr->probability >
+ MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
+ mg->max_prob_rate = index;
+ cur_prob = mr->probability;
+ }
+
+ if (mr->cur_tp > cur_tp) {
+ swap(index, mg->max_tp_rate);
+ cur_tp = mr->cur_tp;
+ mr = minstrel_get_ratestats(mi, index);
+ }
+
+ if (index >= mg->max_tp_rate)
+ continue;
+
+ if (mr->cur_tp > cur_tp2) {
+ mg->max_tp_rate2 = index;
+ cur_tp2 = mr->cur_tp;
+ }
+ }
+ }
+
+ /* 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;
+ cur_tp2 = 0;
+ for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
+ mg = &mi->groups[group];
+ if (!mg->supported)
+ continue;
+
+ mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
+ if (cur_prob_tp < mr->cur_tp &&
+ minstrel_mcs_groups[group].streams == 1) {
+ mi->max_prob_rate = mg->max_prob_rate;
+ cur_prob = mr->cur_prob;
+ }
+
+ mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
+ if (cur_tp < mr->cur_tp) {
+ mi->max_tp_rate = mg->max_tp_rate;
+ cur_tp = mr->cur_tp;
+ }
+
+ mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
+ if (cur_tp2 < mr->cur_tp) {
+ mi->max_tp_rate2 = mg->max_tp_rate2;
+ cur_tp2 = mr->cur_tp;
+ }
+ }
+
+ mi->stats_update = jiffies;
+}
+
+static bool
+minstrel_ht_txstat_valid(struct ieee80211_tx_rate *rate)
+{
+ if (!rate->count)
+ return false;
+
+ if (rate->idx < 0)
+ return false;
+
+ return !!(rate->flags & IEEE80211_TX_RC_MCS);
+}
+
+static void
+minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
+{
+ struct minstrel_mcs_group_data *mg;
+
+ for (;;) {
+ mi->sample_group++;
+ mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
+ mg = &mi->groups[mi->sample_group];
+
+ if (!mg->supported)
+ continue;
+
+ if (++mg->index > MCS_GROUP_RATES) {
+ mg->index = 0;
+ if (++mg->column > ARRAY_SIZE(sample_table))
+ mg->column = 0;
+ }
+ break;
+ }
+}
+
+static void
+minstrel_downgrade_rate(struct minstrel_ht_sta *mi, int *idx, bool primary)
+{
+ int group, orig_group;
+
+ orig_group = group = *idx / MCS_GROUP_RATES;
+ while (group > 0) {
+ group--;
+
+ if (!mi->groups[group].supported)
+ continue;
+
+ if (minstrel_mcs_groups[group].streams >
+ minstrel_mcs_groups[orig_group].streams)
+ continue;
+
+ if (primary)
+ *idx = mi->groups[group].max_tp_rate;
+ else
+ *idx = mi->groups[group].max_tp_rate2;
+ break;
+ }
+}
+
+
+static void
+minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
+ struct ieee80211_sta *sta, void *priv_sta,
+ struct sk_buff *skb)
+{
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+ struct minstrel_ht_sta *mi = &msp->ht;
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct ieee80211_tx_rate *ar = info->status.rates;
+ struct minstrel_rate_stats *rate, *rate2;
+ struct minstrel_priv *mp = priv;
+ bool last = false;
+ int group;
+ int i = 0;
+
+ if (!msp->is_ht)
+ return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
+
+ /* This packet was aggregated but doesn't carry status info */
+ if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
+ !(info->flags & IEEE80211_TX_STAT_AMPDU))
+ return;
+
+ if (!info->status.ampdu_len) {
+ info->status.ampdu_ack_len = 1;
+ info->status.ampdu_len = 1;
+ }
+
+ 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]);
+
+ if (!minstrel_ht_txstat_valid(&ar[i]))
+ break;
+
+ group = minstrel_ht_get_group_idx(&ar[i]);
+ rate = &mi->groups[group].rates[ar[i].idx % 8];
+
+ if (last && (info->flags & IEEE80211_TX_STAT_ACK))
+ rate->success += info->status.ampdu_ack_len;
+
+ 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 > 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 > 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);
+}
+
+static void
+minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+ int index)
+{
+ struct minstrel_rate_stats *mr;
+ const struct mcs_group *group;
+ unsigned int tx_time, tx_time_rtscts, tx_time_data;
+ unsigned int cw = mp->cw_min;
+ unsigned int t_slot = 9; /* FIXME */
+ unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
+
+ mr = minstrel_get_ratestats(mi, index);
+ if (mr->probability < MINSTREL_FRAC(1, 10)) {
+ mr->retry_count = 1;
+ mr->retry_count_rtscts = 1;
+ return;
+ }
+
+ mr->retry_count = 2;
+ mr->retry_count_rtscts = 2;
+ mr->retry_updated = true;
+
+ group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
+ tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len;
+ tx_time = 2 * (t_slot + mi->overhead + tx_time_data);
+ tx_time_rtscts = 2 * (t_slot + mi->overhead_rtscts + tx_time_data);
+ do {
+ cw = (cw << 1) | 1;
+ cw = min(cw, mp->cw_max);
+ tx_time += cw + t_slot + mi->overhead;
+ tx_time_rtscts += cw + t_slot + mi->overhead_rtscts;
+ if (tx_time_rtscts < mp->segment_size)
+ mr->retry_count_rtscts++;
+ } while ((tx_time < mp->segment_size) &&
+ (++mr->retry_count < mp->max_retry));
+}
+
+
+static void
+minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+ struct ieee80211_tx_rate *rate, int index,
+ struct ieee80211_tx_rate_control *txrc,
+ bool sample, bool rtscts)
+{
+ const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
+ struct minstrel_rate_stats *mr;
+
+ mr = minstrel_get_ratestats(mi, index);
+ if (!mr->retry_updated)
+ minstrel_calc_retransmit(mp, mi, index);
+
+ if (rtscts)
+ rate->count = mr->retry_count_rtscts;
+ else
+ rate->count = mr->retry_count;
+
+ rate->flags = IEEE80211_TX_RC_MCS | group->flags;
+ if (txrc->short_preamble)
+ rate->flags |= IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
+ if (txrc->rts || rtscts)
+ rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
+ rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
+}
+
+static inline int
+minstrel_get_duration(int index)
+{
+ const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
+ return group->duration[index % MCS_GROUP_RATES];
+}
+
+static int
+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;
+
+ if (mi->sample_wait > 0) {
+ mi->sample_wait--;
+ return -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];
+ sample_idx += mi->sample_group * MCS_GROUP_RATES;
+
+ /*
+ * When not using MRR, do not sample if the probability is already
+ * higher than 95% to avoid wasting airtime
+ */
+ if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
+ 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) &&
+ mr->sample_skipped < 10)
+ goto next;
+
+ return sample_idx;
+
+next:
+ minstrel_next_sample_idx(mi);
+ return -1;
+}
+
+static void
+minstrel_aggr_check(struct minstrel_priv *mp, struct ieee80211_sta *pubsta, struct sk_buff *skb)
+{
+ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+ struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+ u16 tid;
+
+ if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
+ return;
+
+ if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
+ return;
+
+ tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
+ if (likely(sta->ampdu_mlme.tid_state_tx[tid] != HT_AGG_STATE_IDLE))
+ return;
+
+ ieee80211_start_tx_ba_session(pubsta, tid);
+}
+
+static void
+minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
+ struct ieee80211_tx_rate_control *txrc)
+{
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
+ struct ieee80211_tx_rate *ar = info->status.rates;
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+ struct minstrel_ht_sta *mi = &msp->ht;
+ struct minstrel_priv *mp = priv;
+ int sample_idx;
+
+ if (rate_control_send_low(sta, priv_sta, txrc))
+ return;
+
+ if (!msp->is_ht)
+ return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
+
+ minstrel_aggr_check(mp, sta, txrc->skb);
+
+ sample_idx = minstrel_get_sample_rate(mp, mi);
+ if (sample_idx >= 0) {
+ 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);
+ minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
+ txrc, false, true);
+ }
+ minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate, txrc, false, true);
+
+ ar[3].count = 0;
+ ar[3].idx = -1;
+
+ mi->total_packets++;
+
+ /* wraparound */
+ if (mi->total_packets == ~0) {
+ mi->total_packets = 0;
+ mi->sample_packets = 0;
+ }
+}
+
+static void
+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;
+
+ for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
+ u16 req = 0;
+
+ mi->groups[i].supported = 0;
+ if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
+ if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
+ req |= IEEE80211_HT_CAP_SGI_40;
+ else
+ req |= IEEE80211_HT_CAP_SGI_20;
+ }
+
+ if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
+ req |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
+
+ if ((sta_cap & req) != req)
+ continue;
+
+ mi->groups[i].supported =
+ mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
+ }
+}
+
+static void
+minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
+ struct ieee80211_sta *sta, void *priv_sta)
+{
+ struct minstrel_priv *mp = priv;
+
+ minstrel_ht_update_caps(priv, sband, sta, priv_sta, mp->hw->conf.channel_type);
+}
+
+static void
+minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
+ struct ieee80211_sta *sta, void *priv_sta,
+ u32 changed, enum nl80211_channel_type oper_chan_type)
+{
+ minstrel_ht_update_caps(priv, sband, sta, priv_sta, oper_chan_type);
+}
+
+static void *
+minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
+{
+ struct ieee80211_supported_band *sband;
+ struct minstrel_ht_sta_priv *msp;
+ struct minstrel_priv *mp = priv;
+ struct ieee80211_hw *hw = mp->hw;
+ int max_rates = 0;
+ int i;
+
+ for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
+ sband = hw->wiphy->bands[i];
+ if (sband && sband->n_bitrates > max_rates)
+ max_rates = sband->n_bitrates;
+ }
+
+ msp = kzalloc(sizeof(struct minstrel_ht_sta), gfp);
+ if (!msp)
+ return NULL;
+
+ msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
+ if (!msp->ratelist)
+ goto error;
+
+ msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
+ if (!msp->sample_table)
+ goto error1;
+
+ return msp;
+
+error1:
+ kfree(msp->sample_table);
+error:
+ kfree(msp);
+ return NULL;
+}
+
+static void
+minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
+{
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+
+ kfree(msp->sample_table);
+ kfree(msp->ratelist);
+ kfree(msp);
+}
+
+static void *
+minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
+{
+ return mac80211_minstrel.alloc(hw, debugfsdir);
+}
+
+static void
+minstrel_ht_free(void *priv)
+{
+ mac80211_minstrel.free(priv);
+}
+
+static struct rate_control_ops mac80211_minstrel_ht = {
+ .name = "minstrel_ht",
+ .tx_status = minstrel_ht_tx_status,
+ .get_rate = minstrel_ht_get_rate,
+ .rate_init = minstrel_ht_rate_init,
+ .rate_update = minstrel_ht_rate_update,
+ .alloc_sta = minstrel_ht_alloc_sta,
+ .free_sta = minstrel_ht_free_sta,
+ .alloc = minstrel_ht_alloc,
+ .free = minstrel_ht_free,
+#ifdef CONFIG_MAC80211_DEBUGFS
+ .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
+ .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
+#endif
+};
+
+
+static void
+init_sample_table(void)
+{
+ int col, i, new_idx;
+ u8 rnd[MCS_GROUP_RATES];
+
+ memset(sample_table, 0xff, sizeof(sample_table));
+ for (col = 0; col < SAMPLE_COLUMNS; col++) {
+ for (i = 0; i < MCS_GROUP_RATES; i++) {
+ get_random_bytes(rnd, sizeof(rnd));
+ new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
+
+ while (sample_table[col][new_idx] != 0xff)
+ new_idx = (new_idx + 1) % MCS_GROUP_RATES;
+
+ sample_table[col][new_idx] = i;
+ }
+ }
+}
+
+int __init
+rc80211_minstrel_ht_init(void)
+{
+ init_sample_table();
+ return ieee80211_rate_control_register(&mac80211_minstrel_ht);
+}
+
+void
+rc80211_minstrel_ht_exit(void)
+{
+ ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
+}
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2010 Felix Fietkau <nbd@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __RC_MINSTREL_HT_H
+#define __RC_MINSTREL_HT_H
+
+/*
+ * maximum number of spatial streams to make use of
+ * set this value to 3 once we have drivers that support it
+ */
+#define MINSTREL_MAX_STREAMS 2
+#define MINSTREL_STREAM_GROUPS 4
+
+/* scaled fraction values */
+#define MINSTREL_SCALE 16
+#define MINSTREL_FRAC(val, div) (((val) << MINSTREL_SCALE) / div)
+#define MINSTREL_TRUNC(val) ((val) >> MINSTREL_SCALE)
+
+#define MCS_GROUP_RATES 8
+
+struct mcs_group {
+ u32 flags;
+ unsigned int streams;
+ unsigned int duration[MCS_GROUP_RATES];
+};
+
+struct minstrel_rate_stats {
+ /* current / last sampling period attempts/success counters */
+ unsigned int attempts, last_attempts;
+ unsigned int success, last_success;
+
+ /* total attempts/success counters */
+ u64 att_hist, succ_hist;
+
+ /* current throughput */
+ unsigned int cur_tp;
+
+ /* packet delivery probabilities */
+ unsigned int cur_prob, probability;
+
+ /* maximum retry counts */
+ unsigned int retry_count;
+ unsigned int retry_count_rtscts;
+
+ bool retry_updated;
+ u8 sample_skipped;
+};
+
+struct minstrel_mcs_group_data {
+ u8 index;
+ u8 column;
+
+ /* bitfield of supported MCS rates of this group */
+ u8 supported;
+
+ /* selected primary rates */
+ unsigned int max_tp_rate;
+ unsigned int max_tp_rate2;
+ unsigned int max_prob_rate;
+
+ /* MCS rate statistics */
+ struct minstrel_rate_stats rates[MCS_GROUP_RATES];
+};
+
+struct minstrel_ht_sta {
+ /* ampdu length average (EWMA) */
+ unsigned int avg_ampdu_len;
+
+ /* best throughput rate */
+ unsigned int max_tp_rate;
+
+ /* second best throughput rate */
+ unsigned int max_tp_rate2;
+
+ /* best probability rate */
+ unsigned int max_prob_rate;
+
+ /* time of last status update */
+ unsigned long stats_update;
+
+ /* overhead time in usec for each frame */
+ unsigned int overhead;
+ unsigned int overhead_rtscts;
+
+ unsigned int total_packets;
+ unsigned int sample_packets;
+
+ u8 sample_wait;
+ u8 sample_tries;
+ u8 sample_count;
+
+ /* current MCS group to be sampled */
+ u8 sample_group;
+
+ /* MCS rate group info and statistics */
+ struct minstrel_mcs_group_data groups[MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS];
+};
+
+struct minstrel_ht_sta_priv {
+ union {
+ struct minstrel_ht_sta ht;
+ struct minstrel_sta_info legacy;
+ };
+#ifdef CONFIG_MAC80211_DEBUGFS
+ struct dentry *dbg_stats;
+#endif
+ void *ratelist;
+ void *sample_table;
+ bool is_ht;
+};
+
+void minstrel_ht_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
+void minstrel_ht_remove_sta_debugfs(void *priv, void *priv_sta);
+
+#endif
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2010 Felix Fietkau <nbd@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/debugfs.h>
+#include <linux/ieee80211.h>
+#include <net/mac80211.h>
+#include "rc80211_minstrel.h"
+#include "rc80211_minstrel_ht.h"
+
+extern const struct mcs_group minstrel_mcs_groups[];
+
+static int
+minstrel_ht_stats_open(struct inode *inode, struct file *file)
+{
+ struct minstrel_ht_sta_priv *msp = inode->i_private;
+ struct minstrel_ht_sta *mi = &msp->ht;
+ struct minstrel_debugfs_info *ms;
+ unsigned int i, j, tp, prob, eprob;
+ char *p;
+ int ret;
+
+ if (!msp->is_ht) {
+ inode->i_private = &msp->legacy;
+ ret = minstrel_stats_open(inode, file);
+ inode->i_private = msp;
+ return ret;
+ }
+
+ ms = kmalloc(sizeof(*ms) + 8192, GFP_KERNEL);
+ if (!ms)
+ return -ENOMEM;
+
+ file->private_data = ms;
+ p = ms->buf;
+ p += sprintf(p, "type rate throughput ewma prob this prob "
+ "this succ/attempt success attempts\n");
+ for (i = 0; i < MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS; i++) {
+ char htmode = '2';
+ char gimode = 'L';
+
+ if (!mi->groups[i].supported)
+ continue;
+
+ if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
+ htmode = '4';
+ if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI)
+ gimode = 'S';
+
+ for (j = 0; j < MCS_GROUP_RATES; j++) {
+ struct minstrel_rate_stats *mr = &mi->groups[i].rates[j];
+ int idx = i * MCS_GROUP_RATES + j;
+
+ if (!mi->groups[i].supported & BIT(j))
+ continue;
+
+ p += sprintf(p, "HT%c0/%cGI ", htmode, gimode);
+
+ *(p++) = (idx == mi->max_tp_rate) ? 'T' : ' ';
+ *(p++) = (idx == mi->max_tp_rate2) ? 't' : ' ';
+ *(p++) = (idx == mi->max_prob_rate) ? 'P' : ' ';
+ p += sprintf(p, "MCS%-2u", (minstrel_mcs_groups[i].streams - 1) *
+ MCS_GROUP_RATES + j);
+
+ tp = mr->cur_tp / 10;
+ prob = MINSTREL_TRUNC(mr->cur_prob * 1000);
+ eprob = MINSTREL_TRUNC(mr->probability * 1000);
+
+ p += sprintf(p, " %6u.%1u %6u.%1u %6u.%1u "
+ "%3u(%3u) %8llu %8llu\n",
+ tp / 10, tp % 10,
+ eprob / 10, eprob % 10,
+ prob / 10, prob % 10,
+ mr->last_success,
+ mr->last_attempts,
+ (unsigned long long)mr->succ_hist,
+ (unsigned long long)mr->att_hist);
+ }
+ }
+ p += sprintf(p, "\nTotal packet count:: ideal %d "
+ "lookaround %d\n",
+ max(0, (int) mi->total_packets - (int) mi->sample_packets),
+ mi->sample_packets);
+ p += sprintf(p, "Average A-MPDU length: %d.%d\n",
+ MINSTREL_TRUNC(mi->avg_ampdu_len),
+ MINSTREL_TRUNC(mi->avg_ampdu_len * 10) % 10);
+ ms->len = p - ms->buf;
+
+ return 0;
+}
+
+static const struct file_operations minstrel_ht_stat_fops = {
+ .owner = THIS_MODULE,
+ .open = minstrel_ht_stats_open,
+ .read = minstrel_stats_read,
+ .release = minstrel_stats_release,
+};
+
+void
+minstrel_ht_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir)
+{
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+
+ msp->dbg_stats = debugfs_create_file("rc_stats", S_IRUGO, dir, msp,
+ &minstrel_ht_stat_fops);
+}
+
+void
+minstrel_ht_remove_sta_debugfs(void *priv, void *priv_sta)
+{
+ struct minstrel_ht_sta_priv *msp = priv_sta;
+
+ debugfs_remove(msp->dbg_stats);
+}
--
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