Commit ade6d4a2 authored Mar 24, 2015 by Thomas Huehn Committed by Johannes Berg Apr 01, 2015

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 <thomas@net.t-labs.tu-berlin.de>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

parent 50e55a8e

net/mac80211/rc80211_minstrel.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -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 {

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