Return-path: Received: from mail-wg0-f44.google.com ([74.125.82.44]:36679 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751468AbbCCK2v convert rfc822-to-8bit (ORCPT ); Tue, 3 Mar 2015 05:28:51 -0500 Received: by wghk14 with SMTP id k14so39068176wgh.3 for ; Tue, 03 Mar 2015 02:28:50 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1423568924-11895-1-git-send-email-michal.kazior@tieto.com> <1425374168.2450.17.camel@sipsolutions.net> <1425375418.2450.27.camel@sipsolutions.net> Date: Tue, 3 Mar 2015 11:28:50 +0100 Message-ID: (sfid-20150303_112857_548278_B13570F8) Subject: Re: [PATCH] mac80211: disable u-APSD queues by default From: Michal Kazior To: Krishna Chaitanya Cc: Johannes Berg , linux-wireless Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 3 March 2015 at 11:15, Krishna Chaitanya wrote: > On Tue, Mar 3, 2015 at 3:06 PM, Johannes Berg wrote: >> >>> >> Cisco 4410N originally forced us to enable VO by >>> >> default only because it treated non-VO ACs as >>> >> legacy. >> >>> Mixed mode (uapsd + legacy) is not really the optimal >>> configuration, where we expect STA to send trigger frames periodically >>> to retrieve the DL packets (especially very first packet). >>> >>> But still if we want power save, i suggest going for >>> All u-apsd (0xF), so that AP will inform us by setting the TIM bit >>> and we can retrieve the first frame. >>> (We have this patch internally and it works well). >> >> Except where it doesn't work, like on the Cisco 4410N - see above. > But for that single AP, we are forced to lose efficient power savings > unless user configured explicitly. Correct me if I'm wrong, but u-APSD makes sense only if you have userspace apps aware of it. I don't know any. VoIP traffic uses and it works just because it generate bi-directional traffic in most cases so you have implicit trigger frames generated when you Tx, but that's probably as far as the practical use-case goes, no? You'd still need netfilter rules to reclassify your traffic anyway, wouldn't you? If you mainly wait for data you need to send trigger frames periodically and only userspace app knows what Rx latency is tolerated (that's why relying on driver/firmware auto-trigger generation doesn't cut it). Anyway I don't think you can ask users to do the opposite (i.e. disable u-APSD if they experience problems with APs). Wi-Fi should Just Work. Joys of IOT.. Michał