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[209.132.180.67]) by mx.google.com with ESMTP id e1si3995553ejt.319.2019.11.22.03.21.58; Fri, 22 Nov 2019 03:22:24 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=XSev2sTl; spf=pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-wireless-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728780AbfKVLUU (ORCPT + 99 others); Fri, 22 Nov 2019 06:20:20 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:32424 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729575AbfKVKp5 (ORCPT ); Fri, 22 Nov 2019 05:45:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574419556; 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=XSev2sTlBPMT1y9vX/qQoN7Fr8yOufdNdWx28kvqi/bO2lXwO/qM2NsbVmLL11srZ+I4Ev CNdYP8wIJJQL7/pXLGlUJZHTQgSErcxR08EdQJC3c36HftZozJ0nKoYE63foDq51feQvMP 8j45P/RQEfVgJKLUJI9ysTuXAgS2IXQ= Received: from mail-lj1-f200.google.com (mail-lj1-f200.google.com [209.85.208.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-365-xJ--dzD3Oqe1wTIWcSapGQ-1; Fri, 22 Nov 2019 05:45:53 -0500 Received: by mail-lj1-f200.google.com with SMTP id p25so1211521lji.23 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=MvJyxhLjbe/T4TcxIMLUGblFVuBsjHhfC89YuXtam5Ax7Or6FvqpcTPQLKj+85psWV Jn8ofd7fIoOwDN4DpAeUYVb1HE7bAgoaGx9BNq8iFujr0GClruaQm314YM5GmP2JhGiq 9mrY+65vBMTGiXSsuQY9T3C2DbK6Dh0NDC7afkot9Co7ognpUnHdOADmCHI8IPM5NPqo vMAQWTbRukZ1GW9vk5B43c5EyYwzIE0u7RbCBxd5CYt9azBiCj593P0hHeR/rXTH46I/ nK899SH00rjQzRirQopBd9a8zM1pnaVK8/CTFIXrzQIMztCQGa6IO0AxDUP89ZbELExF KosA== X-Gm-Message-State: APjAAAV5BgBRNDs1jnG9OCCb/8bAAu9g/wsohBbgzdZDWYENLR/Rx42A 5I+r4lT3QXiaUbk6CJq630P0GeoK9JZYQCV73xEuEUy967CKUj3lE1eDdSeOjLtyaDHoXKr8PYX +Farv9P4txqWF1dV8hOu6ta8Mid4= X-Received: by 2002:a2e:b4eb:: with SMTP id s11mr11781013ljm.38.1574419552011; Fri, 22 Nov 2019 02:45:52 -0800 (PST) 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 Subject: Re: [Make-wifi-fast] [PATCH v8 0/2] Implement Airtime-based Queue Limit (AQL) 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: xJ--dzD3Oqe1wTIWcSapGQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org 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