On Thu, Aug 26, 2010 at 1:47 PM, Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> wrote: > Massaging this message a bit and putting it on the public > mailing list. > > On Thu, Aug 26, 2010 at 01:14:36PM -0700, Amod Bodas wrote: >> Thanks Jouni. Even my observations are same i.e I see 1 sec or >> so scan before returning to home channel. Given background scan >> issue looks to be mac80211 related. >> >> Who is lead scan module expert in the community? > > Well Helmut worked on it: > > Author: Helmut Schaa <Helmut.Schaa@xxxxxx> > Date: Wed Feb 24 14:19:21 2010 +0100 > > mac80211: Improve software scan timing > > The current software scan implemenation in mac80211 returns to the operating > channel after each scanned channel. However, in some situations (e.g. no > traffic) it would be nicer to scan a few channels in a row to speed up > the scan itself. > > Hence, after scanning a channel, check if we have queued up any tx frames and > return to the operating channel in that case. > > Unfortunately we don't know if the AP has buffered any frames for us. Hence, > scan only as many channels in a row as the pm_qos latency and the negotiated > listen interval allows us to. > > Signed-off-by: Helmut Schaa <helmut.schaa@xxxxxxxxxxxxxx> > Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx> > > but AFAICT the issues documented below were likely not considered into the > architecture and its the first time I see them pointed out, unless I missed > something. The above commit log shows only the pm_qos latency was taken > into consideration, which I suppose can be modified for now as a hack > to deal with these issues. As suggested by Jouni, I'll test using min(listen_interval, DTIM_PERIOD), this should only help with broadcast / multicast data upon a scan. If there are any other thresholds required by userspace this should likely be configured on the bg scan module I think. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
