mac80211: add standard deviation to Minstrel stats
This patch adds the statistical descriptor "standard deviation" to better describe the current properties of Minstrel and Minstrel-HTs success probability distribution. The standard deviation (SD) is calculated as exponential weighted moving standard deviation (EWMSD) and its current value is added as new column in all rc_stats (in debugfs). Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de> Acked-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com>hifive-unleashed-5.1
Thomas Huehn
Johannes Berg
parent
ade6d4a2ec
commit
5f919abc76
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@ -153,7 +153,7 @@ minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
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}
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/*
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* Recalculate success probabilities and counters for a given rate using EWMA
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* Recalculate statistics and counters of a given rate
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*/
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void
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minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
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@ -161,11 +161,20 @@ minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
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if (unlikely(mrs->attempts > 0)) {
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mrs->sample_skipped = 0;
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mrs->cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
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if (unlikely(!mrs->att_hist))
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if (unlikely(!mrs->att_hist)) {
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mrs->prob_ewma = mrs->cur_prob;
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else
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} else {
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/* update exponential weighted moving variance */
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mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd,
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mrs->cur_prob,
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mrs->prob_ewma,
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EWMA_LEVEL);
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/*update exponential weighted moving avarage */
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mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
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mrs->cur_prob, EWMA_LEVEL);
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mrs->cur_prob,
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EWMA_LEVEL);
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}
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mrs->att_hist += mrs->attempts;
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mrs->succ_hist += mrs->success;
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} else {
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@ -193,7 +202,7 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
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struct minstrel_rate_stats *mrs = &mi->r[i].stats;
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struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
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/* Update success probabilities per rate */
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/* Update statistics of success probability per rate */
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minstrel_calc_rate_stats(mrs);
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/* Sample less often below the 10% chance of success.
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@ -35,6 +35,24 @@ minstrel_ewma(int old, int new, int weight)
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return old + incr;
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}
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/*
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* Perform EWMSD (Exponentially Weighted Moving Standard Deviation) calculation
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*/
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static inline int
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minstrel_ewmsd(int old_ewmsd, int cur_prob, int prob_ewma, int weight)
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{
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int diff, incr, tmp_var;
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/* calculate exponential weighted moving variance */
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diff = MINSTREL_TRUNC((cur_prob - prob_ewma) * 1000000);
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incr = (EWMA_DIV - weight) * diff / EWMA_DIV;
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tmp_var = old_ewmsd * old_ewmsd;
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tmp_var = weight * (tmp_var + diff * incr / 1000000) / EWMA_DIV;
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/* return standard deviation */
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return (u16) int_sqrt(tmp_var);
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}
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struct minstrel_rate_stats {
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/* current / last sampling period attempts/success counters */
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u16 attempts, last_attempts;
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@ -45,9 +63,11 @@ struct minstrel_rate_stats {
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/* statistis of packet delivery probability
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* cur_prob - current prob within last update intervall
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* prob_ewma - exponential weighted moving average of prob */
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* prob_ewma - exponential weighted moving average of prob
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* prob_ewmsd - exp. weighted moving standard deviation of prob */
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unsigned int cur_prob;
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unsigned int prob_ewma;
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u16 prob_ewmsd;
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/* maximum retry counts */
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u8 retry_count;
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@ -85,10 +85,12 @@ minstrel_stats_open(struct inode *inode, struct file *file)
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file->private_data = ms;
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p = ms->buf;
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p += sprintf(p, "\n");
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p += sprintf(p, "best __________rate_________ __statistics__ "
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"________last_______ ______sum-of________\n");
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p += sprintf(p, "rate [name idx airtime max_tp] [ ø(tp) ø(prob)] "
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"[prob.|retry|suc|att] [#success | #attempts]\n");
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p += sprintf(p, "best __________rate_________ ______"
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"statistics______ ________last_______ "
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"______sum-of________\n");
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p += sprintf(p, "rate [name idx airtime max_tp] [ ø(tp) ø(prob) "
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"sd(prob)] [prob.|retry|suc|att] "
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"[#success | #attempts]\n");
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for (i = 0; i < mi->n_rates; i++) {
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struct minstrel_rate *mr = &mi->r[i];
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@ -110,11 +112,13 @@ minstrel_stats_open(struct inode *inode, struct file *file)
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prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);
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eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
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p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u %3u"
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" %3u %-3u %9llu %-9llu\n",
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p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u"
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" %3u.%1u %3u %3u %-3u "
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"%9llu %-9llu\n",
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tp_max / 10, tp_max % 10,
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tp_avg / 10, tp_avg % 10,
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eprob / 10, eprob % 10,
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mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
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prob / 10, prob % 10,
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mrs->retry_count,
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mrs->last_success,
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@ -176,11 +180,12 @@ minstrel_stats_csv_open(struct inode *inode, struct file *file)
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prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);
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eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
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p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"
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p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"
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"%llu,%llu,%d,%d\n",
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tp_max / 10, tp_max % 10,
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tp_avg / 10, tp_avg % 10,
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eprob / 10, eprob % 10,
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mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
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prob / 10, prob % 10,
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mrs->retry_count,
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mrs->last_success,
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@ -86,11 +86,13 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
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prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);
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eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
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p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u "
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"%3u %3u %-3u %9llu %-9llu\n",
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p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u"
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" %3u.%1u %3u %3u %-3u "
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"%9llu %-9llu\n",
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tp_max / 10, tp_max % 10,
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tp_avg / 10, tp_avg % 10,
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eprob / 10, eprob % 10,
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mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
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prob / 10, prob % 10,
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mrs->retry_count,
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mrs->last_success,
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@ -128,10 +130,10 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file)
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p += sprintf(p, "\n");
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p += sprintf(p, " best ____________rate__________ "
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"__statistics__ ________last_______ "
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"______statistics______ ________last_______ "
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"______sum-of________\n");
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p += sprintf(p, "mode guard # rate [name idx airtime max_tp] "
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"[ ø(tp) ø(prob)] [prob.|retry|suc|att] [#success | "
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"[ ø(tp) ø(prob) sd(prob)] [prob.|retry|suc|att] [#success | "
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"#attempts]\n");
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p = minstrel_ht_stats_dump(mi, MINSTREL_CCK_GROUP, p);
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@ -229,10 +231,12 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
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prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);
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eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
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p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,%llu,%llu,",
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p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,"
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"%u,%llu,%llu,",
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tp_max / 10, tp_max % 10,
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tp_avg / 10, tp_avg % 10,
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eprob / 10, eprob % 10,
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mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,
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prob / 10, prob % 10,
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mrs->retry_count,
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mrs->last_success,
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