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authorThomas Huehn <thomas@net.t-labs.tu-berlin.de>2015-03-24 21:09:42 +0100
committerJohannes Berg <johannes.berg@intel.com>2015-04-01 20:44:33 +0200
commitade6d4a2ec57d258bc181a155288c267dd8cf094 (patch)
tree60df72e1b0f08c2f544a5ae4cfcec181f5ae0de1 /net/mac80211/rc80211_minstrel.h
parent50e55a8ea76fb593403cc09767b6371c17364ba8 (diff)
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>
Diffstat (limited to 'net/mac80211/rc80211_minstrel.h')
-rw-r--r--net/mac80211/rc80211_minstrel.h7
1 files changed, 6 insertions, 1 deletions
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 {