Re: Flush scan list on resume

[Howard Chu <hyc symas com>]

Tony Espy wrote:
> Dan Williams wrote:
> > On Wed, 2009-02-04 at 15:40 -0800, Howard Chu wrote:
> > > OK. I suggest a compromise then, since fetching kernel time will also be
> > > expensive if done frequently - just fetch it at driver load and resume time,
> > > and store it as a<base>  in the driver. Cache entries then store base+jiffy.
> > > This allows cache stamps to continue to be cheap, but also solves the
> > > sleep/resume mismatch.
> > Yeah, that might work.  Want to whip up a quick patch we can use for
> > further discussion?

Will look into it.

> I still think simple ( ie. either have mac80211 handle the expiration or
> flush of scan results on resume ) wins out over the more complicated
> approach of having the connection manager handle expiration of older
> scan results.
>
> Also a mobile device ( eg. a netbook or OLPC ) could be moving relative
> to the same set of access points while in S3 ( ie. within a single
> office and/or building ), and that the cached scan results after resume
> could reflect inaccurate relative signal strengths of the the APs.  This
> could effect roaming performance.

Yeah, good point. This is also trivial to implement - just call 
ieee80211_rx_bss_list_deinit(local) in pm.c: __iee80211_suspend(). I'm going 
to play with this approach first.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/