diff options
| author | Felix Fietkau <nbd@nbd.name> | 2021-01-15 13:02:42 +0100 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2021-01-22 09:11:37 +0100 |
| commit | 347c2989a8ba8a231f2ffc0635f2f36fedd30bde (patch) | |
| tree | 12e46040a239db3c9867e1530942922b6547676c /net/mac80211/rc80211_minstrel_ht.c | |
| parent | mac80211: minstrel_ht: increase stats update interval (diff) | |
| download | linux-347c2989a8ba8a231f2ffc0635f2f36fedd30bde.tar.xz linux-347c2989a8ba8a231f2ffc0635f2f36fedd30bde.zip | |
mac80211: minstrel_ht: fix rounding error in throughput calculation
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@nbd.name>
Link: https://lore.kernel.org/r/20210115120242.89616-10-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net/mac80211/rc80211_minstrel_ht.c')
| -rw-r--r-- | net/mac80211/rc80211_minstrel_ht.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c index 782b4668a3da..e35948f4e1bf 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)); } /* |