On lower data rates, the throughput calculation has a significant rounding error, causing rates like 48M and 54M OFDM to share the same throughput value with >= 90% success probablity. This is because the result of the division (prob_avg * 1000) / nsecs is really small (8 in this example). Improve accuracy by moving over some zeroes, making better use of the full range of u32 before the division. Signed-off-by: Felix Fietkau <nbd@xxxxxxxx> --- net/mac80211/rc80211_minstrel_ht.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c index 6496aa39f60b..9e010c8dd063 100644 --- a/net/mac80211/rc80211_minstrel_ht.c +++ b/net/mac80211/rc80211_minstrel_ht.c @@ -445,10 +445,9 @@ minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate, * (prob is scaled - see MINSTREL_FRAC above) */ if (prob_avg > MINSTREL_FRAC(90, 100)) - return MINSTREL_TRUNC(100000 * ((MINSTREL_FRAC(90, 100) * 1000) - / nsecs)); - else - return MINSTREL_TRUNC(100000 * ((prob_avg * 1000) / nsecs)); + prob_avg = MINSTREL_FRAC(90, 100); + + return MINSTREL_TRUNC(100 * ((prob_avg * 1000000) / nsecs)); } /* -- 2.28.0
