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mac80211: minstrel: reduce minstrel_mcs_groups size
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By storing a shift value for all duration values of a group, we can
reduce precision by a neglegible amount to make it fit into a u16 value.
This improves cache footprint and reduces size:

Before:
   text    data     bss     dec     hex filename
  10024     116       0   10140    279c rc80211_minstrel_ht.o

After:
   text    data     bss     dec     hex filename
   9368     116       0    9484    250c rc80211_minstrel_ht.o

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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Felix Fietkau authored and Johannes Berg committed Oct 11, 2018
1 parent b1c4f68 commit 202df50
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Showing 3 changed files with 93 additions and 78 deletions.
153 changes: 80 additions & 73 deletions net/mac80211/rc80211_minstrel_ht.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,22 +52,23 @@
_streams - 1

/* MCS rate information for an MCS group */
#define MCS_GROUP(_streams, _sgi, _ht40) \
#define MCS_GROUP(_streams, _sgi, _ht40, _s) \
[GROUP_IDX(_streams, _sgi, _ht40)] = { \
.streams = _streams, \
.shift = _s, \
.flags = \
IEEE80211_TX_RC_MCS | \
(_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) \
MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234) >> _s, \
MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) >> _s \
} \
}

Expand All @@ -80,35 +81,36 @@
#define BW2VBPS(_bw, r3, r2, r1) \
(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)

#define VHT_GROUP(_streams, _sgi, _bw) \
#define VHT_GROUP(_streams, _sgi, _bw, _s) \
[VHT_GROUP_IDX(_streams, _sgi, _bw)] = { \
.streams = _streams, \
.shift = _s, \
.flags = \
IEEE80211_TX_RC_VHT_MCS | \
(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH : \
_bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
.duration = { \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 117, 54, 26)), \
BW2VBPS(_bw, 117, 54, 26)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 234, 108, 52)), \
BW2VBPS(_bw, 234, 108, 52)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 351, 162, 78)), \
BW2VBPS(_bw, 351, 162, 78)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 468, 216, 104)), \
BW2VBPS(_bw, 468, 216, 104)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 702, 324, 156)), \
BW2VBPS(_bw, 702, 324, 156)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 936, 432, 208)), \
BW2VBPS(_bw, 936, 432, 208)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1053, 486, 234)), \
BW2VBPS(_bw, 1053, 486, 234)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1170, 540, 260)), \
BW2VBPS(_bw, 1170, 540, 260)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1404, 648, 312)), \
BW2VBPS(_bw, 1404, 648, 312)) >> _s, \
MCS_DURATION(_streams, _sgi, \
BW2VBPS(_bw, 1560, 720, 346)) \
BW2VBPS(_bw, 1560, 720, 346)) >> _s \
} \
}

Expand All @@ -121,19 +123,20 @@
(CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \
CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))

#define CCK_DURATION_LIST(_short) \
CCK_ACK_DURATION(10, _short), \
CCK_ACK_DURATION(20, _short), \
CCK_ACK_DURATION(55, _short), \
CCK_ACK_DURATION(110, _short)
#define CCK_DURATION_LIST(_short, _s) \
CCK_ACK_DURATION(10, _short) >> _s, \
CCK_ACK_DURATION(20, _short) >> _s, \
CCK_ACK_DURATION(55, _short) >> _s, \
CCK_ACK_DURATION(110, _short) >> _s

#define CCK_GROUP \
#define CCK_GROUP(_s) \
[MINSTREL_CCK_GROUP] = { \
.streams = 0, \
.flags = 0, \
.shift = _s, \
.duration = { \
CCK_DURATION_LIST(false), \
CCK_DURATION_LIST(true) \
CCK_DURATION_LIST(false, _s), \
CCK_DURATION_LIST(true, _s) \
} \
}

Expand All @@ -151,47 +154,47 @@ MODULE_PARM_DESC(minstrel_vht_only,
* BW -> SGI -> #streams
*/
const struct mcs_group minstrel_mcs_groups[] = {
MCS_GROUP(1, 0, BW_20),
MCS_GROUP(2, 0, BW_20),
MCS_GROUP(3, 0, BW_20),
MCS_GROUP(1, 0, BW_20, 5),
MCS_GROUP(2, 0, BW_20, 4),
MCS_GROUP(3, 0, BW_20, 4),

MCS_GROUP(1, 1, BW_20),
MCS_GROUP(2, 1, BW_20),
MCS_GROUP(3, 1, BW_20),
MCS_GROUP(1, 1, BW_20, 5),
MCS_GROUP(2, 1, BW_20, 4),
MCS_GROUP(3, 1, BW_20, 4),

MCS_GROUP(1, 0, BW_40),
MCS_GROUP(2, 0, BW_40),
MCS_GROUP(3, 0, BW_40),
MCS_GROUP(1, 0, BW_40, 4),
MCS_GROUP(2, 0, BW_40, 4),
MCS_GROUP(3, 0, BW_40, 4),

MCS_GROUP(1, 1, BW_40),
MCS_GROUP(2, 1, BW_40),
MCS_GROUP(3, 1, BW_40),
MCS_GROUP(1, 1, BW_40, 4),
MCS_GROUP(2, 1, BW_40, 4),
MCS_GROUP(3, 1, BW_40, 4),

CCK_GROUP,
CCK_GROUP(8),

VHT_GROUP(1, 0, BW_20),
VHT_GROUP(2, 0, BW_20),
VHT_GROUP(3, 0, BW_20),
VHT_GROUP(1, 0, BW_20, 5),
VHT_GROUP(2, 0, BW_20, 4),
VHT_GROUP(3, 0, BW_20, 4),

VHT_GROUP(1, 1, BW_20),
VHT_GROUP(2, 1, BW_20),
VHT_GROUP(3, 1, BW_20),
VHT_GROUP(1, 1, BW_20, 5),
VHT_GROUP(2, 1, BW_20, 4),
VHT_GROUP(3, 1, BW_20, 4),

VHT_GROUP(1, 0, BW_40),
VHT_GROUP(2, 0, BW_40),
VHT_GROUP(3, 0, BW_40),
VHT_GROUP(1, 0, BW_40, 4),
VHT_GROUP(2, 0, BW_40, 4),
VHT_GROUP(3, 0, BW_40, 4),

VHT_GROUP(1, 1, BW_40),
VHT_GROUP(2, 1, BW_40),
VHT_GROUP(3, 1, BW_40),
VHT_GROUP(1, 1, BW_40, 4),
VHT_GROUP(2, 1, BW_40, 4),
VHT_GROUP(3, 1, BW_40, 4),

VHT_GROUP(1, 0, BW_80),
VHT_GROUP(2, 0, BW_80),
VHT_GROUP(3, 0, BW_80),
VHT_GROUP(1, 0, BW_80, 4),
VHT_GROUP(2, 0, BW_80, 4),
VHT_GROUP(3, 0, BW_80, 4),

VHT_GROUP(1, 1, BW_80),
VHT_GROUP(2, 1, BW_80),
VHT_GROUP(3, 1, BW_80),
VHT_GROUP(1, 1, BW_80, 4),
VHT_GROUP(2, 1, BW_80, 4),
VHT_GROUP(3, 1, BW_80, 4),
};

static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
Expand Down Expand Up @@ -307,7 +310,8 @@ minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
if (group != MINSTREL_CCK_GROUP)
nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);

nsecs += minstrel_mcs_groups[group].duration[rate];
nsecs += minstrel_mcs_groups[group].duration[rate] <<
minstrel_mcs_groups[group].shift;

/*
* For the throughput calculation, limit the probability value to 90% to
Expand Down Expand Up @@ -755,12 +759,19 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
minstrel_ht_update_rates(mp, mi);
}

static inline int
minstrel_get_duration(int index)
{
const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
unsigned int duration = group->duration[index % MCS_GROUP_RATES];
return duration << group->shift;
}

static void
minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
int index)
{
struct minstrel_rate_stats *mrs;
const struct mcs_group *group;
unsigned int tx_time, tx_time_rtscts, tx_time_data;
unsigned int cw = mp->cw_min;
unsigned int ctime = 0;
Expand All @@ -779,8 +790,7 @@ minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
mrs->retry_count_rtscts = 2;
mrs->retry_updated = true;

group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
tx_time_data = minstrel_get_duration(index) * ampdu_len / 1000;

/* Contention time for first 2 tries */
ctime = (t_slot * cw) >> 1;
Expand Down Expand Up @@ -874,28 +884,32 @@ minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
int group = mi->max_prob_rate / MCS_GROUP_RATES;
const struct mcs_group *g = &minstrel_mcs_groups[group];
int rate = mi->max_prob_rate % MCS_GROUP_RATES;
unsigned int duration;

/* Disable A-MSDU if max_prob_rate is bad */
if (mi->groups[group].rates[rate].prob_ewma < MINSTREL_FRAC(50, 100))
return 1;

duration = g->duration[rate];
duration <<= g->shift;

/* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
if (g->duration[rate] > MCS_DURATION(1, 0, 52))
if (duration > MCS_DURATION(1, 0, 52))
return 500;

/*
* If the rate is slower than single-stream MCS4, limit A-MSDU to usual
* data packet size
*/
if (g->duration[rate] > MCS_DURATION(1, 0, 104))
if (duration > MCS_DURATION(1, 0, 104))
return 1600;

/*
* If the rate is slower than single-stream MCS7, or if the max throughput
* rate success probability is less than 75%, limit A-MSDU to twice the usual
* data packet size
*/
if (g->duration[rate] > MCS_DURATION(1, 0, 260) ||
if (duration > MCS_DURATION(1, 0, 260) ||
(minstrel_ht_get_prob_ewma(mi, mi->max_tp_rate[0]) <
MINSTREL_FRAC(75, 100)))
return 3200;
Expand Down Expand Up @@ -942,13 +956,6 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
rate_control_set_rates(mp->hw, mi->sta, 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)
{
Expand Down
7 changes: 4 additions & 3 deletions net/mac80211/rc80211_minstrel_ht.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,9 +33,10 @@
#define MCS_GROUP_RATES 10

struct mcs_group {
u32 flags;
unsigned int streams;
unsigned int duration[MCS_GROUP_RATES];
u16 flags;
u8 streams;
u8 shift;
u16 duration[MCS_GROUP_RATES];
};

extern const struct mcs_group minstrel_mcs_groups[];
Expand Down
11 changes: 9 additions & 2 deletions net/mac80211/rc80211_minstrel_ht_debugfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
static const int bitrates[4] = { 10, 20, 55, 110 };
int idx = i * MCS_GROUP_RATES + j;
unsigned int prob_ewmsd;
unsigned int duration;

if (!(mi->supported[i] & BIT(j)))
continue;
Expand Down Expand Up @@ -95,7 +96,9 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
p += sprintf(p, " %3u ", idx);

/* tx_time[rate(i)] in usec */
tx_time = DIV_ROUND_CLOSEST(mg->duration[j], 1000);
duration = mg->duration[j];
duration <<= mg->shift;
tx_time = DIV_ROUND_CLOSEST(duration, 1000);
p += sprintf(p, "%6u ", tx_time);

tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
Expand Down Expand Up @@ -204,6 +207,7 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
static const int bitrates[4] = { 10, 20, 55, 110 };
int idx = i * MCS_GROUP_RATES + j;
unsigned int prob_ewmsd;
unsigned int duration;

if (!(mi->supported[i] & BIT(j)))
continue;
Expand Down Expand Up @@ -238,7 +242,10 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
}

p += sprintf(p, "%u,", idx);
tx_time = DIV_ROUND_CLOSEST(mg->duration[j], 1000);

duration = mg->duration[j];
duration <<= mg->shift;
tx_time = DIV_ROUND_CLOSEST(duration, 1000);
p += sprintf(p, "%u,", tx_time);

tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
Expand Down

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