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From: Felix Fietkau <nbd@nbd.name>
Date: Wed, 14 Dec 2016 20:17:06 +0100
Subject: [PATCH] mac80211: minstrel: store probability variance instead of
standard deviation
This avoids the costly int_sqrt calls in the statistics update and moves
it to the debugfs code instead.
This also fixes an overflow in the previous standard deviation
calculation.
Signed-off-by: Thomas Huehn <thomas.huehn@evernet-eg.de>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -168,10 +168,10 @@ minstrel_calc_rate_stats(struct minstrel
mrs->prob_ewma = cur_prob;
} else {
/* update exponential weighted moving variance */
- mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd,
- cur_prob,
- mrs->prob_ewma,
- EWMA_LEVEL);
+ mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
+ cur_prob,
+ mrs->prob_ewma,
+ EWMA_LEVEL);
/*update exponential weighted moving avarage */
mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
--- a/net/mac80211/rc80211_minstrel.h
+++ b/net/mac80211/rc80211_minstrel.h
@@ -36,21 +36,16 @@ minstrel_ewma(int old, int new, int weig
}
/*
- * Perform EWMSD (Exponentially Weighted Moving Standard Deviation) calculation
+ * Perform EWMV (Exponentially Weighted Moving Variance) calculation
*/
static inline int
-minstrel_ewmsd(int old_ewmsd, int cur_prob, int prob_ewma, int weight)
+minstrel_ewmv(int old_ewmv, int cur_prob, int prob_ewma, int weight)
{
- int diff, incr, tmp_var;
+ int diff, incr;
- /* calculate exponential weighted moving variance */
- diff = MINSTREL_TRUNC((cur_prob - prob_ewma) * 1000000);
+ diff = cur_prob - prob_ewma;
incr = (EWMA_DIV - weight) * diff / EWMA_DIV;
- tmp_var = old_ewmsd * old_ewmsd;
- tmp_var = weight * (tmp_var + diff * incr / 1000000) / EWMA_DIV;
-
- /* return standard deviation */
- return (u16) int_sqrt(tmp_var);
+ return weight * (old_ewmv + MINSTREL_TRUNC(diff * incr)) / EWMA_DIV;
}
struct minstrel_rate_stats {
@@ -65,7 +60,7 @@ struct minstrel_rate_stats {
* prob_ewma - exponential weighted moving average of prob
* prob_ewmsd - exp. weighted moving standard deviation of prob */
unsigned int prob_ewma;
- u16 prob_ewmsd;
+ u16 prob_ewmv;
/* maximum retry counts */
u8 retry_count;
@@ -151,6 +146,14 @@ struct minstrel_debugfs_info {
char buf[];
};
+/* Get EWMSD (Exponentially Weighted Moving Standard Deviation) * 10 */
+static inline int
+minstrel_get_ewmsd10(struct minstrel_rate_stats *mrs)
+{
+ unsigned int ewmv = mrs->prob_ewmv;
+ return int_sqrt(MINSTREL_TRUNC(ewmv * 1000 * 1000));
+}
+
extern const struct rate_control_ops mac80211_minstrel;
void minstrel_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
void minstrel_remove_sta_debugfs(void *priv, void *priv_sta);
--- a/net/mac80211/rc80211_minstrel_debugfs.c
+++ b/net/mac80211/rc80211_minstrel_debugfs.c
@@ -93,6 +93,7 @@ minstrel_stats_open(struct inode *inode,
for (i = 0; i < mi->n_rates; i++) {
struct minstrel_rate *mr = &mi->r[i];
struct minstrel_rate_stats *mrs = &mi->r[i].stats;
+ unsigned int prob_ewmsd;
*(p++) = (i == mi->max_tp_rate[0]) ? 'A' : ' ';
*(p++) = (i == mi->max_tp_rate[1]) ? 'B' : ' ';
@@ -108,6 +109,7 @@ minstrel_stats_open(struct inode *inode,
tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
+ prob_ewmsd = minstrel_get_ewmsd10(mrs);
p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u"
" %3u %3u %-3u "
@@ -115,7 +117,7 @@ minstrel_stats_open(struct inode *inode,
tp_max / 10, tp_max % 10,
tp_avg / 10, tp_avg % 10,
eprob / 10, eprob % 10,
- mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
+ prob_ewmsd / 10, prob_ewmsd % 10,
mrs->retry_count,
mrs->last_success,
mrs->last_attempts,
@@ -159,6 +161,7 @@ minstrel_stats_csv_open(struct inode *in
for (i = 0; i < mi->n_rates; i++) {
struct minstrel_rate *mr = &mi->r[i];
struct minstrel_rate_stats *mrs = &mi->r[i].stats;
+ unsigned int prob_ewmsd;
p += sprintf(p, "%s" ,((i == mi->max_tp_rate[0]) ? "A" : ""));
p += sprintf(p, "%s" ,((i == mi->max_tp_rate[1]) ? "B" : ""));
@@ -174,13 +177,14 @@ minstrel_stats_csv_open(struct inode *in
tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
+ prob_ewmsd = minstrel_get_ewmsd10(mrs);
p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"
"%llu,%llu,%d,%d\n",
tp_max / 10, tp_max % 10,
tp_avg / 10, tp_avg % 10,
eprob / 10, eprob % 10,
- mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
+ prob_ewmsd / 10, prob_ewmsd % 10,
mrs->retry_count,
mrs->last_success,
mrs->last_attempts,
--- a/net/mac80211/rc80211_minstrel_ht_debugfs.c
+++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
@@ -41,6 +41,7 @@ minstrel_ht_stats_dump(struct minstrel_h
struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
static const int bitrates[4] = { 10, 20, 55, 110 };
int idx = i * MCS_GROUP_RATES + j;
+ unsigned int prob_ewmsd;
if (!(mi->supported[i] & BIT(j)))
continue;
@@ -84,6 +85,7 @@ minstrel_ht_stats_dump(struct minstrel_h
tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_ewma);
eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
+ prob_ewmsd = minstrel_get_ewmsd10(mrs);
p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u"
" %3u %3u %-3u "
@@ -91,7 +93,7 @@ minstrel_ht_stats_dump(struct minstrel_h
tp_max / 10, tp_max % 10,
tp_avg / 10, tp_avg % 10,
eprob / 10, eprob % 10,
- mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
+ prob_ewmsd / 10, prob_ewmsd % 10,
mrs->retry_count,
mrs->last_success,
mrs->last_attempts,
@@ -185,6 +187,7 @@ minstrel_ht_stats_csv_dump(struct minstr
struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
static const int bitrates[4] = { 10, 20, 55, 110 };
int idx = i * MCS_GROUP_RATES + j;
+ unsigned int prob_ewmsd;
if (!(mi->supported[i] & BIT(j)))
continue;
@@ -225,13 +228,14 @@ minstrel_ht_stats_csv_dump(struct minstr
tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_ewma);
eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
+ prob_ewmsd = minstrel_get_ewmsd10(mrs);
p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,"
"%u,%llu,%llu,",
tp_max / 10, tp_max % 10,
tp_avg / 10, tp_avg % 10,
eprob / 10, eprob % 10,
- mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
+ prob_ewmsd / 10, prob_ewmsd % 10,
mrs->retry_count,
mrs->last_success,
mrs->last_attempts,
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