Return-path: Received: from smtp.nokia.com ([192.100.122.230]:28283 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759781Ab0I0QdN (ORCPT ); Mon, 27 Sep 2010 12:33:13 -0400 Subject: Re: active vs. passive scans From: Luciano Coelho To: ext Johannes Berg Cc: ext Chuck Crisler , "linux-wireless@vger.kernel.org" In-Reply-To: <1285600151.4043.23.camel@jlt3.sipsolutions.net> References: <15713CDD627C41D39E4B9725AE2B241D@ChuckPC> <1285599964.5768.120.camel@chilepepper> <1285600151.4043.23.camel@jlt3.sipsolutions.net> Content-Type: text/plain; charset="UTF-8" Date: Mon, 27 Sep 2010 19:32:58 +0300 Message-ID: <1285605178.30315.3.camel@powerslave> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, 2010-09-27 at 17:09 +0200, ext Johannes Berg wrote: > On Mon, 2010-09-27 at 18:06 +0300, Luciano Coelho wrote: > > > Usually the drivers stay for a certain period of time in each channel, > > and that normally doesn't change if you have active or passive scan. So > > there will be no improvement in the overall scan speed. Of course you > > could do some tweaks that might improve scanning performance in specific > > cases. > > It's certainly different with mac80211: > > #define IEEE80211_CHANNEL_TIME (HZ / 33) > #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8) Right... Even in the wl1271 driver's hw scan we stay longer on each channel for passive scans. Obviously just listening to beacons we need to wait more, because probe_reqs should be responded quickly. -- Cheers, Luca.