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 [205.139.110.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 324B93B2A4 for ; Thu, 21 Nov 2019 05:05:24 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574330723; 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=PKJaj7sZjc6579dv29AEceQXePo8ctco2c9W8uoDneA=; b=I9EuNpwBQtQhMpVHFfDSBGULjn1fBrwDDujknEJPk1WhRMMRrV3bdjGaYpYZPl65D1OuB8 qUt1RBQuhpExzLm6JIBkG5ocwCcDLssn2xBjy/KFlIcQ8L+xn4Fu6T3CiKG071Pg0yGqgj xG/zNPJpIULEQx9D7yVLt0Wc8MiciCA= Received: from mail-lf1-f72.google.com (mail-lf1-f72.google.com [209.85.167.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-422-kmPN1_AWNEa-q6D3xBfDOg-1; Thu, 21 Nov 2019 05:05:20 -0500 Received: by mail-lf1-f72.google.com with SMTP id u5so759047lfm.21 for ; Thu, 21 Nov 2019 02:05:19 -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=//BqCXRTQqZ/4bta4yIpsp57qADMVHEdiZm1YRgSpeA=; b=PPbxxWTHLgNk4pcqXlKSV71l3hGu/b5wvWt+W0uuLCBA0kEQSMmkpVVz8E2CQpx+L6 qcEpXEfqXSNf5TT6mK9vZcUdou9MzTwEjUjBrZdliZGmWcFUg4b+2JWP7ZHHBtSG14U8 Rh8eBvSUPCH76nUP2sOa3R954rd99TDikARy3Rc+ACzNIO1nchS6GPhhfbCZxgyJOLFG fF6QQP5eiN8LmxVq2gKsOsqvWTUw6mnqMSVU714jbR9G3UIk5oLz0iwxdjfohrO7UcdJ Lys2U3x16GhQG2RB/ebD4WS0WqKhlVAkL8/gW9UYX9XuCJOqwg2beSwvT1c065XjysVO Ml2g== X-Gm-Message-State: APjAAAUot7c06/0j+/2Gc/hwWtnSuUTielAnewsa2Vfj5RzBNNXagA88 Zmw8hBAWmbyTl3OduUlwoTE3R+ijwRJSkM2qkk9RoRYJvQhFQlHbfPs3ryv08njkJn0ng/LuwO6 HUWJFVGXkZ/ZX75puExBeUJ5ZAFu+f0Sc8t4= X-Received: by 2002:a2e:7204:: with SMTP id n4mr6346078ljc.139.1574330718669; Thu, 21 Nov 2019 02:05:18 -0800 (PST) X-Google-Smtp-Source: APXvYqzXXZK5aQ2sI3akJsmS3V+7YzHQ/ORRUwFTYPXJDdbx7Vs18vLc8MY97Tv2U8yVbABpVGsluw== X-Received: by 2002:a2e:7204:: with SMTP id n4mr6346072ljc.139.1574330718505; Thu, 21 Nov 2019 02:05:18 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk (borgediget.toke.dk. [85.204.121.218]) by smtp.gmail.com with ESMTPSA id y5sm1078673lfg.5.2019.11.21.02.05.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Nov 2019 02:05:17 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 65D611818B9; Thu, 21 Nov 2019 11:05:16 +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> X-Clacks-Overhead: GNU Terry Pratchett Date: Thu, 21 Nov 2019 11:05:16 +0100 Message-ID: <87a78p8rz7.fsf@toke.dk> MIME-Version: 1.0 X-MC-Unique: kmPN1_AWNEa-q6D3xBfDOg-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: Thu, 21 Nov 2019 10:05:24 -0000 Kan Yan writes: >> It would be interesting to get some samples of the actual sojourn time >> as seen by CoDel in mac80211. Might be doable with bpftrace... > > I will try to add some trace event to get the sojourn time for the > next round of tests. In theory, this ought to produce a histogram of sojourn times (in microseconds): bpftrace -e 'kretprobe:codel_skb_time_func { @sojourn =3D lhist((nsecs - (r= etval << 10))/1000, 0, 100000, 1000); }' 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? It would be interesting to see if it works for you, assuming you can get bpftrace to work on your test system :) -Toke