From ade6d4a2ec57d258bc181a155288c267dd8cf094 Mon Sep 17 00:00:00 2001 From: Thomas Huehn Date: Tue, 24 Mar 2015 21:09:42 +0100 Subject: [PATCH] mac80211: reduce calculation costs of EWMA This patch reduces the calculation costs of the EWMA macro from "2x multiplication and 1 addition" down to "1x multiplication and 2x additions". This slightly improves performance depending on the CPU architecture. Signed-off-by: Thomas Huehn Acked-by: Felix Fietkau Signed-off-by: Johannes Berg --- net/mac80211/rc80211_minstrel.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h index 0083036161af..9c85a610b57b 100644 --- a/net/mac80211/rc80211_minstrel.h +++ b/net/mac80211/rc80211_minstrel.h @@ -27,7 +27,12 @@ static inline int minstrel_ewma(int old, int new, int weight) { - return (new * (EWMA_DIV - weight) + old * weight) / EWMA_DIV; + int diff, incr; + + diff = new - old; + incr = (EWMA_DIV - weight) * diff / EWMA_DIV; + + return old + incr; } struct minstrel_rate_stats { -- 2.39.5