On Sat, Oct 6, 2018 at 11:18 AM Felix Fietkau <[email protected]> wrote: > > On 2018-10-06 19:59, Dave Taht wrote: > > On Sat, Oct 6, 2018 at 10:37 AM Felix Fietkau <[email protected]> wrote: > >> > >> When there are few packets (e.g. for sampling attempts), the exponentially > >> weighted variance is usually vastly overestimated, making the resulting > >> data > >> essentially useless. As far as I know, there has not been any practical use > >> for this, so let's not waste any cycles on it. > >> > >> Signed-off-by: Felix Fietkau <[email protected]> > >> --- > >> net/mac80211/rc80211_minstrel.c | 6 ----- > >> net/mac80211/rc80211_minstrel.h | 26 +--------------------- > >> net/mac80211/rc80211_minstrel_debugfs.c | 14 ++++-------- > >> net/mac80211/rc80211_minstrel_ht_debugfs.c | 14 ++++-------- > >> 4 files changed, 9 insertions(+), 51 deletions(-) > >> > >> diff --git a/net/mac80211/rc80211_minstrel.c > >> b/net/mac80211/rc80211_minstrel.c > >> index dead57ba9eac..a34e9c2ca626 100644 > >> --- a/net/mac80211/rc80211_minstrel.c > >> +++ b/net/mac80211/rc80211_minstrel.c > >> @@ -167,12 +167,6 @@ minstrel_calc_rate_stats(struct minstrel_rate_stats > >> *mrs) > >> if (unlikely(!mrs->att_hist)) { > >> mrs->prob_ewma = cur_prob; > >> } else { > >> - /* update exponential weighted moving variance */ > >> - mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv, > >> - cur_prob, > >> - mrs->prob_ewma, > >> - EWMA_LEVEL); > >> - > >> /*update exponential weighted moving avarage */ > >> mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma, > >> cur_prob, > >> diff --git a/net/mac80211/rc80211_minstrel.h > >> b/net/mac80211/rc80211_minstrel.h > >> index 54b2b2c3e10a..23ec953e3a24 100644 > >> --- a/net/mac80211/rc80211_minstrel.h > >> +++ b/net/mac80211/rc80211_minstrel.h > >> @@ -35,19 +35,6 @@ minstrel_ewma(int old, int new, int weight) > >> return old + incr; > >> } > >> > >> -/* > >> - * Perform EWMV (Exponentially Weighted Moving Variance) calculation > >> - */ > > > > I worry about this one. where are you getting your proof from? > I've done quite a few measurements myself to see if this can be usable > for further rate control improvements or for the upcoming TPC work. > The data this generates simply fluctuates wildly and incoherently based > on the sampling behavior, making it completely useless. > Together with Thomas (who introduced this code), I tried a few times to > fix this, but couldn't find any way to make it coherent and usable. > > Thomas and I both agreed that it's better to just remove it until > somebody has a better idea what to do. > > Also, this was only used for debugfs statistics, not for any actual rate > control behavior.
OK, thanks. I'm totally delighted to see this patchset otherwise. > - Felix -- Dave Täht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-205-9740
