From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id CD8E13B29E for ; Fri, 22 Nov 2019 05:45:55 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574419555; 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=Fk4U8YS7q9LLa/grnzbGdGnG0Qz10lovogQ8pGu2fqo=; b=JMhpYL+Jp1Eloaeg2RomJfbZO9+NcyDEIUqmtuIer5tTRXr8T3ovQ908DvvMMjXD4/Xou6 gmgsobX/tow37lABIDiUPiivIg7GleUZV/9zEZCJWc/q9n7GAgoIW0DnQvYikkMlnC3hHg t5V3EaAujTUmnY5Hj0Ny0i3Bh2wYY+c= Received: from mail-lj1-f198.google.com (mail-lj1-f198.google.com [209.85.208.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-343-oM_7YsqyM1-XrNoo513QDQ-1; Fri, 22 Nov 2019 05:45:53 -0500 Received: by mail-lj1-f198.google.com with SMTP id o20so1228981ljg.0 for ; Fri, 22 Nov 2019 02:45:53 -0800 (PST) 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; bh=3YUXrxz/9/yZd+6SITQARhpw627qctr8pyINzH15x7I=; b=leqDJEKE5vwoJlvOeSf/YG5F29CRkRlcAo/2xxvsRLlBMejmGdj2hA/I9y2uLOIHJR +hWGHhtZqkg7qgQstp+y03ZsrkOVJk1AJoqL0x6NQlA8hOTbZVEamvc5lh2v/RFXo7OY qhRspxBEbyOfq0xzhlMstsoQtCrVoXTbckI0vAGjQmdmEc72+ofndHH5NnjhfbJek+cd kvNxRFsKeg+HYF1wDKsy1/dq4uTvUhR5KoTjy1BPFp8YbphFNCh0/5ibzlayF7DJZKHx /QWHCNMplTjTano4RSXS/MP0IwoQsnyuWBnLXa0MAqwaaDsjeeAN0BfJakVeURLlxarj 4S6Q== X-Gm-Message-State: APjAAAVaXhBNyahcX2hoPWQikcBIuT0QYmDNmzAorbcvxDEH2Q0nui+i fC43MjE+NqpKsfVxXMMWTVOmnPA2hbWbCuJ1yAbsjo8KO5pdJOLIxvIVMTrU9EwznWg1Zj9cVTf 6Gxs6oVh5Zfy3xQPy5D9u2AFChCix3ypNxLY= X-Received: by 2002:a2e:b4eb:: with SMTP id s11mr11781014ljm.38.1574419552011; Fri, 22 Nov 2019 02:45:52 -0800 (PST) X-Google-Smtp-Source: APXvYqwasaXDtX4MXmTufMchsNxvY8RgZ/y/8Wj+hpnVwKvzPvDpORYbjFKz7XUktpYMgpbvBTWFSw== X-Received: by 2002:a2e:b4eb:: with SMTP id s11mr11780993ljm.38.1574419551804; Fri, 22 Nov 2019 02:45:51 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([2a00:7660:6da:443::2]) by smtp.gmail.com with ESMTPSA id 129sm1015345lfj.86.2019.11.22.02.45.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Nov 2019 02:45:50 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 159341800B3; Fri, 22 Nov 2019 11:45:50 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Kan Yan Cc: Dave Taht , Rajkumar Manoharan , Kevin Hayes , Make-Wifi-fast , linux-wireless , Yibo Zhao , John Crispin , Johannes Berg , Lorenzo Bianconi , Felix Fietkau In-Reply-To: References: <20191115014846.126007-1-kyan@google.com> <8736eiam8f.fsf@toke.dk> <87a78p8rz7.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Fri, 22 Nov 2019 11:45:50 +0100 Message-ID: <87muco5gv5.fsf@toke.dk> MIME-Version: 1.0 X-MC-Unique: oM_7YsqyM1-XrNoo513QDQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] [PATCH v8 0/2] Implement Airtime-based Queue Limit (AQL) X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Nov 2019 10:45:55 -0000 Kan Yan writes: >> In theory, this ought to produce a histogram of sojourn times (in >> microseconds): >> bpftrace -e 'kretprobe:codel_skb_time_func { @sojourn =3D lhist((nsecs - > (retval << 10))/1000, 0, 100000, 1000); }' > > Thanks for the tips! > >> Can't get the CoDel drop mechanism to trigger on my system at all, >> though (a laptop running on iwl). I guess because there's queue >> backpressure to userspace first? > > What's the tcp_congestion_control in your system? Maybe it is BBR that > prevents bufferbloat. It's not BBR, just plain old CUBIC. I've seen the issue before that it's almost impossible to build a queue in the mac80211 layer when the TCP session is originated on the local machine, though... >> It would be interesting to see if it works for you, assuming you can get >> bpftrace to work on your test system :) > > I can enable required kernel configuration easily, but cross-compile > bpftrace for an ARM64 platform may take some time and effort. Yeah, bpftrace can be a bit of a pain to get running; but it may be worth the investment longer term as well. It really is quite useful! :) Some links: Install guide: https://github.com/iovisor/bpftrace/blob/master/INSTALL.md Tutorial by one-liners: https://github.com/iovisor/bpftrace/blob/master/docs/tutorial_one_liners.md Reference guide: https://github.com/iovisor/bpftrace/blob/master/docs/reference_guide.md#5-t= racepoint-static-tracing-kernel-level -Toke