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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable 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 CEDF2C10F14 for ; Tue, 16 Apr 2019 09:29:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A94B2086A for ; Tue, 16 Apr 2019 09:29:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729097AbfDPJ3c (ORCPT ); Tue, 16 Apr 2019 05:29:32 -0400 Received: from orcrist.hmeau.com ([104.223.48.154]:46388 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727828AbfDPJ3Y (ORCPT ); Tue, 16 Apr 2019 05:29:24 -0400 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtps (Exim 4.89 #2 (Debian)) id 1hGKOw-0002bJ-OQ; Tue, 16 Apr 2019 17:29:14 +0800 Received: from herbert by gondobar with local (Exim 4.89) (envelope-from ) id 1hGKOt-0008Ko-Cw; Tue, 16 Apr 2019 17:29:11 +0800 Date: Tue, 16 Apr 2019 17:29:11 +0800 From: Herbert Xu To: Arend Van Spriel Cc: Johannes Berg , Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= , Felix Fietkau , linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 5/5] mac80211: set NETIF_F_LLTX when using intermediate tx queues Message-ID: <20190416092911.76nyeodbxu5bsqx4@gondor.apana.org.au> References: <20190316170634.13125-1-nbd@nbd.name> <20190316170634.13125-5-nbd@nbd.name> <87sgvmvg9g.fsf@toke.dk> <773e4dff-29fd-22b4-e4bc-cd5a94c66dc2@broadcom.com> <20190416074444.pdubbh6fbibdnhi7@gondor.apana.org.au> <73b18131-2777-da5c-a6ee-9d9b3e13cd06@broadcom.com> <20190416083636.5ttvezqyhzr2worg@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Tue, Apr 16, 2019 at 11:17:53AM +0200, Arend Van Spriel wrote: > On 4/16/2019 10:37 AM, Johannes Berg wrote: > > It is true because we have an entire buffering layer in mac80211 (in > > this case at least) and never push back to the stack. > > Ok, so the crux is the "never push back to the stack" part? Well, the > internal TXQ and how that is used is obviously enabling that ;-) So assuming that these drivers all have a TX queue length of zero and therefore do not make use of Linux queueing disciplines then yes techincally LLTX is fine. However, I must say that it is much better to provide real congestion feedback to the stack when you can because otherwise things like UDP may fall apart. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt