From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from nbd.name ([46.4.11.11]:36293 "EHLO nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758353Ab3BHOEV (ORCPT ); Fri, 8 Feb 2013 09:04:21 -0500 Message-ID: <511505E1.9080009@openwrt.org> (sfid-20130208_150424_313449_F5604662) Date: Fri, 08 Feb 2013 15:04:17 +0100 From: Felix Fietkau MIME-Version: 1.0 To: Sujith Manoharan CC: linux-wireless@vger.kernel.org, mcgrof@qca.qualcomm.com Subject: Re: [RFC] ath9k: remove ath9k_rate_control References: <1360329197-72631-1-git-send-email-nbd@openwrt.org> <20756.65038.7020.514691@gargle.gargle.HOWL> In-Reply-To: <20756.65038.7020.514691@gargle.gargle.HOWL> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2013-02-08 2:30 PM, Sujith Manoharan wrote: > Felix Fietkau wrote: >> In many tests throughput with ath9k_rate_control has been shown to be >> worse than with minstrel_ht (the mac8021 default RC). >> >> This module also has some other problems, like starting to use the >> highest possible rate early in the connection, causing problems with >> reliability of connection/authentication attempts. >> >> It also has a much more limited search space, ignoring many potentially >> useful rates, caused by the design decision to operate on a sorted rate >> set with the assumption that higher rates are always more unreliable >> than lower rates. In some scenarios this assumption is not true, and >> this can cause it to fall back to a really bad rate. >> >> minstrel_ht has been tested extensively in AP and client mode by lots of >> users (mostly in the OpenWrt project, where it has been the default for >> years). >> >> The only advantage that ath9k_rate_control previously had over minstrel_ht >> was the support for using CCK rates as fall back in case MCS rates got >> too bad, but this has now also been taken care of. > > Various rates are marked as invalid in the ath9k rate control module. I don't > know all the reasons, but the recommendation to disable certain rates came from > the internal algorithms team. How will this be handled ? I'm pretty sure it's because the algorithm isn't designed to handle more rates. It's a step-up/step-down type algorithm, and those typically only work with a sorted rateset, preferably duplicate free. Minstrel_ht selects rates in a different way that doesn't have the same limitations, so it can use the full rateset. - Felix