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 <tho...@net.t-labs.tu-berlin.de> --- net/mac80211/rc80211_minstrel.c | 19 ++++++++++++++----- net/mac80211/rc80211_minstrel.h | 22 +++++++++++++++++++++- net/mac80211/rc80211_minstrel_debugfs.c | 19 ++++++++++++------- net/mac80211/rc80211_minstrel_ht_debugfs.c | 14 +++++++++----- 4 files changed, 56 insertions(+), 18 deletions(-) diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c index c2afe51..30512d0 100644 --- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -156,7 +156,7 @@ minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi) } /* -* Recalculate success probabilities and counters for a given rate using EWMA +* Recalculate statistics and counters of a given rate */ void minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs) @@ -164,11 +164,20 @@ minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs) if (unlikely(mrs->attempts > 0)) { mrs->sample_skipped = 0; mrs->cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts); - if (unlikely(!mrs->att_hist)) + if (unlikely(!mrs->att_hist)) { mrs->prob_ewma = mrs->cur_prob; - else + } else { + /* update exponential weighted moving variance */ + mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd, + mrs->cur_prob, + mrs->prob_ewma, + EWMA_LEVEL); + + /*update exponential weighted moving avarage */ mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma, - mrs->cur_prob, EWMA_LEVEL); + mrs->cur_prob, + EWMA_LEVEL); + } mrs->att_hist += mrs->attempts; mrs->succ_hist += mrs->success; } else { @@ -195,7 +204,7 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi) struct minstrel_rate *mr = &mi->r[i]; struct minstrel_rate_stats *mrs = &mi->r[i].stats; - /* Update success probabilities per rate */ + /* Update statistics of success probability per rate */ minstrel_calc_rate_stats(mrs); /* Sample less often below the 10% chance of success. diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h index 38158b0..713c81e 100644 --- a/net/mac80211/rc80211_minstrel.h +++ b/net/mac80211/rc80211_minstrel.h @@ -35,6 +35,24 @@ minstrel_ewma(int old, int new, int weight) return old + incr; } +/* + * Perform EWMSD (Exponentially Weighted Moving Standard Deviation) calculation + */ +static inline int +minstrel_ewmsd(int old_ewmsd, int cur_prob, int prob_ewma, int weight) +{ + int diff, incr, tmp_var; + + /* calculate exponential weighted moving variance */ + diff = MINSTREL_TRUNC((cur_prob - prob_ewma) * 1000000); + 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); +} + struct minstrel_rate_stats { /* current / last sampling period attempts/success counters */ u16 attempts, last_attempts; @@ -45,9 +63,11 @@ struct minstrel_rate_stats { /* statistis of packet delivery probability * cur_prob - current prob within last update intervall - * prob_ewma - exponential weighted moving average of prob */ + * prob_ewma - exponential weighted moving average of prob + * prob_ewmsd - exp. weighted moving standard deviation of prob */ unsigned int cur_prob; unsigned int prob_ewma; + u16 prob_ewmsd; /* maximum retry counts */ u8 retry_count; diff --git a/net/mac80211/rc80211_minstrel_debugfs.c b/net/mac80211/rc80211_minstrel_debugfs.c index 3ed69ef..0a60bac 100644 --- a/net/mac80211/rc80211_minstrel_debugfs.c +++ b/net/mac80211/rc80211_minstrel_debugfs.c @@ -85,10 +85,12 @@ minstrel_stats_open(struct inode *inode, struct file *file) file->private_data = ms; p = ms->buf; p += sprintf(p, "\n"); - p += sprintf(p, "best __________rate_________ __statistics__ " - "________last_______ ______sum-of________\n"); - p += sprintf(p, "rate [name idx airtime max_tp] [ ø(tp) ø(prob)] " - "[prob.|retry|suc|att] [#success | #attempts]\n"); + p += sprintf(p, "best __________rate_________ ______" + "statistics______ ________last_______ " + "______sum-of________\n"); + p += sprintf(p, "rate [name idx airtime max_tp] [ ø(tp) ø(prob) " + "sd(prob)] [prob.|retry|suc|att] " + "[#success | #attempts]\n"); for (i = 0; i < mi->n_rates; i++) { struct minstrel_rate *mr = &mi->r[i]; @@ -110,11 +112,13 @@ minstrel_stats_open(struct inode *inode, struct file *file) prob = MINSTREL_TRUNC(mrs->cur_prob * 1000); eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000); - p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u %3u" - " %3u %-3u %9llu %-9llu\n", + p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u" + " %3u.%1u %3u %3u %-3u " + "%9llu %-9llu\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 / 10, prob % 10, mrs->retry_count, mrs->last_success, @@ -180,11 +184,12 @@ minstrel_stats_csv_open(struct inode *inode, struct file *file) prob = MINSTREL_TRUNC(mrs->cur_prob * 1000); eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000); - p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u," + p += sprintf(p, "%u.%u,%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 / 10, prob % 10, mrs->retry_count, mrs->last_success, diff --git a/net/mac80211/rc80211_minstrel_ht_debugfs.c b/net/mac80211/rc80211_minstrel_ht_debugfs.c index de034e4..e950059 100644 --- a/net/mac80211/rc80211_minstrel_ht_debugfs.c +++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c @@ -86,11 +86,13 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p) prob = MINSTREL_TRUNC(mrs->cur_prob * 1000); eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000); - p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u " - "%3u %3u %-3u %9llu %-9llu\n", + p += sprintf(p, "%4u.%1u %4u.%1u %3u.%1u %3u.%1u" + " %3u.%1u %3u %3u %-3u " + "%9llu %-9llu\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 / 10, prob % 10, mrs->retry_count, mrs->last_success, @@ -128,10 +130,10 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file) p += sprintf(p, "\n"); p += sprintf(p, " best ____________rate__________ " - "__statistics__ ________last_______ " + "______statistics______ ________last_______ " "______sum-of________\n"); p += sprintf(p, "mode guard # rate [name idx airtime max_tp] " - "[ ø(tp) ø(prob)] [prob.|retry|suc|att] [#success | " + "[ ø(tp) ø(prob) sd(prob)] [prob.|retry|suc|att] [#success | " "#attempts]\n"); p = minstrel_ht_stats_dump(mi, MINSTREL_CCK_GROUP, p); @@ -232,10 +234,12 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p, prob = MINSTREL_TRUNC(mrs->cur_prob * 1000); eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000); - p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,%llu,%llu,", + p += sprintf(p, "%u.%u,%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 / 10, prob % 10, mrs->retry_count, mrs->last_success, -- 2.3.0 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html