From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from nbd.name ([88.198.39.176]:55360 "EHLO ds10.nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755770Ab0JINI6 (ORCPT ); Sat, 9 Oct 2010 09:08:58 -0400 Message-ID: <4CB06966.9070905@openwrt.org> Date: Sat, 09 Oct 2010 15:08:54 +0200 From: Felix Fietkau MIME-Version: 1.0 To: Helmut Schaa CC: linux-wireless@vger.kernel.org, linville@tuxdriver.com, lrodriguez@atheros.com, br1@einfach.org Subject: Re: [PATCH 1/3] cfg80211: add channel utilization stats to the survey command References: <1286584771-76663-1-git-send-email-nbd@openwrt.org> <201010091417.25727.helmut.schaa@googlemail.com> In-Reply-To: <201010091417.25727.helmut.schaa@googlemail.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2010-10-09 2:17 PM, Helmut Schaa wrote: > Am Samstag 09 Oktober 2010 schrieb Felix Fietkau: >> Using these, user space can calculate a relative channel utilization >> with arbitrary intervals by regularly taking snapshots of the survey >> results. > > What if you've got multiple consumers, wouldn't that mess up the > survey results? > > I mean, for example mac80211 and/or hostapd might want to use the busy time > statistics for the BSS load IE while a different userspace process might > want to monitor the channel utilization in order to detect a worsening > channel condition. > > If the consumers happen to use the same interval and request the survey > very soon after each other one consumer will get the values on a nice (close > to the query interval) time base while the other one will get the values > based on a very small interval (which might lower the value's > representativeness). Multiple consumers work just fine, since the survey results are relative to the time the hardware started using the channel, not relative to the last request. Maybe my description was a bit unclear on that part. - Felix