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@xxxxxxxxxxxxxxxxxxxxxxx>
---
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 6693d8d..38158b0 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 {
--
2.2.2
--
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