--- /dev/null
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 10 Feb 2018 12:45:47 +0100
+Subject: [PATCH] mac80211: minstrel: reduce minstrel_mcs_groups size
+
+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>
+---
+
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -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 \
+ } \
+ }
+
+@@ -80,9 +81,10 @@
+ #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) | \
+@@ -90,25 +92,25 @@
+ _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 \
+ } \
+ }
+
+@@ -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) \
+ } \
+ }
+
+@@ -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;
+@@ -307,7 +310,8 @@ minstrel_ht_get_tp_avg(struct minstrel_h
+ 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
+@@ -780,7 +784,7 @@ minstrel_calc_retransmit(struct minstrel
+ 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 = (group->duration[index % MCS_GROUP_RATES] << group->shift) * ampdu_len / 1000;
+
+ /* Contention time for first 2 tries */
+ ctime = (t_slot * cw) >> 1;
+@@ -880,14 +884,14 @@ minstrel_ht_get_max_amsdu_len(struct min
+ return 1;
+
+ /* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
+- if (g->duration[rate] > MCS_DURATION(1, 0, 52))
++ if ((g->duration[rate] << g->shift) > 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 ((g->duration[rate] << g->shift) > MCS_DURATION(1, 0, 104))
+ return 1600;
+
+ /*
+@@ -895,7 +899,7 @@ minstrel_ht_get_max_amsdu_len(struct min
+ * 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 ((g->duration[rate] << g->shift) > MCS_DURATION(1, 0, 260) ||
+ (minstrel_ht_get_prob_ewma(mi, mi->max_tp_rate[0]) <
+ MINSTREL_FRAC(75, 100)))
+ return 3200;
+@@ -946,7 +950,7 @@ 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];
++ return group->duration[index % MCS_GROUP_RATES] << group->shift;
+ }
+
+ static int
+--- a/net/mac80211/rc80211_minstrel_ht.h
++++ b/net/mac80211/rc80211_minstrel_ht.h
+@@ -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[];
+--- a/net/mac80211/rc80211_minstrel_ht_debugfs.c
++++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
+@@ -95,7 +95,7 @@ minstrel_ht_stats_dump(struct minstrel_h
+ p += sprintf(p, " %3u ", idx);
+
+ /* tx_time[rate(i)] in usec */
+- tx_time = DIV_ROUND_CLOSEST(mg->duration[j], 1000);
++ tx_time = DIV_ROUND_CLOSEST(mg->duration[j] << mg->shift, 1000);
+ p += sprintf(p, "%6u ", tx_time);
+
+ tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
+@@ -238,7 +238,7 @@ minstrel_ht_stats_csv_dump(struct minstr
+ }
+
+ p += sprintf(p, "%u,", idx);
+- tx_time = DIV_ROUND_CLOSEST(mg->duration[j], 1000);
++ tx_time = DIV_ROUND_CLOSEST(mg->duration[j] << mg->shift, 1000);
+ p += sprintf(p, "%u,", tx_time);
+
+ tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
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