From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5090C433E0 for ; Wed, 17 Jun 2020 07:45:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1486208B3 for ; Wed, 17 Jun 2020 07:45:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726025AbgFQHpg (ORCPT ); Wed, 17 Jun 2020 03:45:36 -0400 Received: from simonwunderlich.de ([79.140.42.25]:57774 "EHLO simonwunderlich.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725901AbgFQHpf (ORCPT ); Wed, 17 Jun 2020 03:45:35 -0400 X-Greylist: delayed 77322 seconds by postgrey-1.27 at vger.kernel.org; Wed, 17 Jun 2020 03:45:35 EDT Received: from [IPv6:2003:c5:9715:4400:7e76:35ff:fe14:e6d7] (p200300c5971544007e7635fffe14e6d7.dip0.t-ipconnect.de [IPv6:2003:c5:9715:4400:7e76:35ff:fe14:e6d7]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by simonwunderlich.de (Postfix) with ESMTPSA id 9E47A62055; Wed, 17 Jun 2020 09:45:34 +0200 (CEST) Subject: Re: [PATCH] mac80211: mesh: add mesh_param "mesh_nolearn" to skip path discovery From: =?UTF-8?Q?Linus_L=c3=bcssing?= To: =?UTF-8?Q?Linus_L=c3=bcssing?= , Johannes Berg Cc: linux-wireless@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org, Sven Eckelmann , Simon Wunderlich References: <20200616095358.20143-1-linus.luessing@c0d3.blue> Message-ID: <6bef8071-f897-b972-dbf9-17198361dc4e@simonwunderlich.de> Date: Wed, 17 Jun 2020 09:45:34 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 16/06/2020 12:16, Linus Lüssing wrote: >> The new mesh_nolearn parameter allows to skip the PREQ/PREP exchange in >> this scenario, leading to a reduced delay, reduced packet buffering and >> simplifies HWMP in general. And a third observation we've made with HWMP: When running iperf with 16 parallel TCP streams and the default HWMP parameters over two 4x4 802.11ac Wave 2 wifi cards transmitting about 800-1000 MBit/s in total, HWMP becomes quite unstable. We see frequent PREQ/PREP retransmissions and also PERR messages, leading to spurious break downs in the throughput. When using just 8 TCP streams, so with a little less saturation and stress of the channel, iperf staticstics are stable. So maybe there would be some potential for optimizations, too, like somehow prioritizing HWMP messages more, or maybe making the default HWMP parameters a bit more conservative. Or just disabling the HWMP PREP/PREQ/PERR exchange with this new configuration option would at least help the ones that are using another mesh routing protocol on top, who are maybe more familiar with the parameters of their specific routing protocol than with the HWMP parameters. Regards, Linus