On Fri, Nov 23, 2018 at 01:34:54PM +0100, Stefan Sperling wrote: > Every time we settle for the same AP after a background scan, > a timeout value is increased to avoid repeated background scans > in situations where no better AP is available. > > The backoff currently increments in steps of half a second. > This causes very frequent background scans for a few minutes > after association to an AP with a weak signal. If my math is > correct, we reach a backoff interval of one minute only after > 120 background scans that found no new AP. > > We could easily double or triple this backoff. > With this diff, we back off by one more second each time we end > up settling for the same AP. We could probably backoff even more, > but I'd prefer to try a relatively small change, for now.
Would it make sense to use an exponential backoff with a maximum? > Tested with an AP where iwn(4) reports -62dBm and triggers > background scans most of the time. > > ok? > > Index: ieee80211_input.c > =================================================================== > RCS file: /cvs/src/sys/net80211/ieee80211_input.c,v > retrieving revision 1.202 > diff -u -p -r1.202 ieee80211_input.c > --- ieee80211_input.c 7 Aug 2018 18:13:14 -0000 1.202 > +++ ieee80211_input.c 23 Nov 2018 11:36:42 -0000 > @@ -276,7 +276,7 @@ ieee80211_input(struct ifnet *ifp, struc > (ic->ic_flags & IEEE80211_F_BGSCAN) == 0 && > (ic->ic_flags & IEEE80211_F_DESBSSID) == 0) > timeout_add_msec(&ic->ic_bgscan_timeout, > - 500 * (ic->ic_bgscan_fail + 1)); > + 500 * (2 * (ic->ic_bgscan_fail + 1))); Why not make this just 1000 * (ic->ic_bgscan_fail + 1)? > } > } > > > > -- :wq Claudio
