From 4f0bc9c61bae9c74ffcf5dbdbd241cbf0ec3a44e Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Wed, 14 Dec 2016 20:47:00 +0100 Subject: 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 Signed-off-by: Felix Fietkau Signed-off-by: Johannes Berg --- net/mac80211/rc80211_minstrel.h | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) (limited to 'net/mac80211/rc80211_minstrel.h') diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h index 03716fddaf24..ea86e6784154 100644 --- a/net/mac80211/rc80211_minstrel.h +++ b/net/mac80211/rc80211_minstrel.h @@ -36,21 +36,16 @@ minstrel_ewma(int old, int new, int weight) } /* - * 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); -- cgit v1.2.3