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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 D1949CA9EA0 for ; Fri, 18 Oct 2019 14:01:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A678D21925 for ; Fri, 18 Oct 2019 14:01:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gtMWhQke" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408701AbfJROBd (ORCPT ); Fri, 18 Oct 2019 10:01:33 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:22293 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2408689AbfJROBc (ORCPT ); Fri, 18 Oct 2019 10:01:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571407290; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M9RSTGVJD9xVIyj975EqK/c+6MLtw+vWyhQYOOPRwQ4=; b=gtMWhQkejBmapTnLvD/RSLq6oAdomwnPK1p3BduXCgPVSkwLq2u8b5grRDNWRCG+TRY7Gi NNmff6tws23WRA0MPNe/B27p4TYL/sk0f8OTKX2Fui9eke9y4v3nxL92D5bCW2XjmoUZmf M/wg9lVnMsqLQblqzIwKRPc/1CHl5H8= Received: from mail-lj1-f199.google.com (mail-lj1-f199.google.com [209.85.208.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-222-Fpxwl3oxPnOwGr0TYykhIg-1; Fri, 18 Oct 2019 10:01:12 -0400 Received: by mail-lj1-f199.google.com with SMTP id x13so1090021ljj.18 for ; Fri, 18 Oct 2019 07:01:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version:content-transfer-encoding; bh=9KU3AOEPNJNeSCWouDLYLTZDs7qEv20m2zC3KeyYxCQ=; b=Pr46+KduVpXiIm65Zc4U4eiKdlLAFZHHDwMhke4hrYiB4FysI3xlkJ5yRCw7R8AjjS dUMbl4kzNAgr3C3e7mklMmTlYFXP1Rk5oYAYaTDYmwyUp/EkK4z1yh+Ux/0bqAedOM9M H5npUHjoW3SqBKGEYzbPpmXMoimBAwjTzshkouLRI04fVoeYZJ1vl5Dz+vYXlfZkYueM OkrX7IJbhaXdKvr+ybvkper8Sd9L3/+Lr7M+XAXDz046hrd7wBWOmABEnOTGhLaB1Zzj /R/Mh2j24KP75Zei2TAl3075cHtP6KkQtEzQS/0f/XEcTjI5s0OzrLnGM3hQdPGQ4Mkw 2ilw== X-Gm-Message-State: APjAAAXR54F+g29fTp/3kEjhUxNE6Mkf+wC504IHLO4R5VMhthayT+Eu tYig7zMFFPgPv2plvTg1l9oQH2u2dnmiOhLeMhTKiksT3fyuJUUTihe35Ixi/7Zy1CoD+RGtOZH sYiYCNMJU4V8CLiIHuZ0pX0DOlJU= X-Received: by 2002:a19:641b:: with SMTP id y27mr6274401lfb.3.1571407271185; Fri, 18 Oct 2019 07:01:11 -0700 (PDT) X-Google-Smtp-Source: APXvYqwC6odn8LyJJs0daZtmkS6VFaA8BtPD78mDU4XrBdIGwZMhS0aV6Gnwq4KieL+5R/+KfSjfzQ== X-Received: by 2002:a19:641b:: with SMTP id y27mr6274369lfb.3.1571407270886; Fri, 18 Oct 2019 07:01:10 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a00:7660:6da:443::2]) by smtp.gmail.com with ESMTPSA id l25sm2867020ljg.72.2019.10.18.07.01.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Oct 2019 07:01:10 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 0D5871804B6; Fri, 18 Oct 2019 16:01:09 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Johannes Berg , Kan Yan Cc: linux-wireless@vger.kernel.org, make-wifi-fast@lists.bufferbloat.net, ath10k@lists.infradead.org, John Crispin , Lorenzo Bianconi , Felix Fietkau , Rajkumar Manoharan , Kevin Hayes Subject: Re: [PATCH v2 1/4] mac80211: Rearrange ieee80211_tx_info to make room for tx_time_est In-Reply-To: <9fc60b546b54b40357264d67536733251cf39ebe.camel@sipsolutions.net> References: <157115993755.2500430.12214017471129215800.stgit@toke.dk> <157115993866.2500430.13989567853855880476.stgit@toke.dk> <87sgnqe4wg.fsf@toke.dk> <10b885b3238cede2d99c6134bebcc0c8ba6f6b10.camel@sipsolutions.net> <87imomdvsj.fsf@toke.dk> <9fc60b546b54b40357264d67536733251cf39ebe.camel@sipsolutions.net> X-Clacks-Overhead: GNU Terry Pratchett Date: Fri, 18 Oct 2019 16:01:09 +0200 Message-ID: <87d0eudufu.fsf@toke.dk> MIME-Version: 1.0 X-MC-Unique: Fpxwl3oxPnOwGr0TYykhIg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Johannes Berg writes: > On Fri, 2019-10-18 at 15:31 +0200, Toke H=C3=B8iland-J=C3=B8rgensen wrote= : > >> Well, let's try to do the actual math... A full-size (1538 bytes) packet >> takes ~2050 microseconds to transmit at 6 Mbps. Adding in overhead, it's >> certainly still less that 4096 us, so 12 bits is plenty. > > What about A-MSDUs? But I guess maximum continous transmissions are at > most 4ms anyway, so a single packet should never be longer. Ah yeah, those could be a bit bigger, but yeah, 4ms should at least be enough. >> That leaves >> four bits for the ACK status ID if we just split the u16; if we only >> ever have "a handful", that should be enough, no? > > It's how many are in flight at a time, 16 doesn't seem likely to happen, > but I don't really know what applications are doing with it now. > Probably only wpa_s for the EAPOL TX status. Right. Well in that case, let's try it. As long as we fail in a reasonable way, we can just see if we run into anything that breaks? I guess in this case that means rejecting requests from userspace if we run out of IDs rather than silently wrapping and returning wrong data :) >> We could also split 5/11. That would support up to 32 ACK IDs, and we >> can just truncate the airtime at 2048 us, which is not a big deal I'd >> say. > > We can also play with the units of the airtime, e.g. making that a > multiple of 2 or 4 us? Seems unlikely to matter much? Sure, that's a good point! Increments of 4us means we can fit 4ms is 10 bits, leaving plenty of space for ACK IDs (hopefully). I'll rework the series to use that instead :) -Toke