From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 9EFFE3B29E for ; Thu, 21 Nov 2019 20:50:34 -0500 (EST) Received: by mail-lj1-x242.google.com with SMTP id 139so5492660ljf.1 for ; Thu, 21 Nov 2019 17:50:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Fj7tsWrTuSDW0fRA1bEngOKjspSC9pyOKq+yaYDhJJk=; b=LjfUya7+ElcA3dDI95zupLcZNas6Smazw0xiXDRCedV4rL5P6+F8qM1V70exFaZ4Aj xWiK+onWWK3XLrRblSWKZ0h9qhnwdiysdp3nxdYwFB2qkphBJffdFYIQC3kaXERgI97H +WPqAvm3/6r1a0SiWz04FfFdCAVqQtGw7sd72jqRj0JFkMY68k+b2ujc91aLreELgZiY fz/1g1fVkShP8LpX1WXQzrpft7DBxJmH5t32eaUUCS1H7f2KfE9C71uDLLaLpsZux1+w hOXlsoI5Sp8nH4If5Am7ZgHgTZJI1h3Q46F8Dydgth7mxiniDWTadNJAL3rpr9dbDG2E Llhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Fj7tsWrTuSDW0fRA1bEngOKjspSC9pyOKq+yaYDhJJk=; b=Lz0irtnYnRId+hBktGm+/EXH/8c+yp9rXHbWrl1OevrzgtkQpYb7rRbA02Wg3bCEhI HLclYBG53NG+9k7kqVRHgPS0Lw6MKA/y+eCES90r9sCIwcdyOHbd6STH1G18SZaQJpyA DFpUIfAT9poehXCrOpkQd1rZT+1WAe2OiXmYLCQpfr18fiF8Ta4E4rCCiehVwWqWitGX u0CLiW91AjVl+JzpuOyECO0XtvW/q4K3TIC882DyJn0T6AwJ7uANBE9DmtkZwT01wP/P ggG93ypqNZR4bes1qvCx2Q7DiwKkpmjxZtcW2G6oeDVUp2M3t9LE0jJ41cUG0i79HqKc cepQ== X-Gm-Message-State: APjAAAW4C2RUE6Az9wMOSCKvlJ3qkLlZnEEg8KkHRWlEsjPPk9ex/zJp i7CPp4TSPUMRRMn5pTR1lGmjk3sBu0yWcfFgk0N38Q== X-Google-Smtp-Source: APXvYqwLTgWtT8AazSd+kQC1BkMMU0E4hxND8KgyVfABe84KjqlAPX6E2DiQijpnmbi0UdZckwphM5zafIHYRQqcDH8= X-Received: by 2002:a2e:9ecf:: with SMTP id h15mr10053875ljk.173.1574387433117; Thu, 21 Nov 2019 17:50:33 -0800 (PST) MIME-Version: 1.0 References: <20191115014846.126007-1-kyan@google.com> <8736eiam8f.fsf@toke.dk> <87a78p8rz7.fsf@toke.dk> In-Reply-To: <87a78p8rz7.fsf@toke.dk> From: Kan Yan Date: Thu, 21 Nov 2019 17:50:21 -0800 Message-ID: To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: Dave Taht , Rajkumar Manoharan , Kevin Hayes , Make-Wifi-fast , linux-wireless , Yibo Zhao , John Crispin , Johannes Berg , Lorenzo Bianconi , Felix Fietkau Content-Type: multipart/alternative; boundary="000000000000b11d0a0597e5a3c6" 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 01:50:34 -0000 --000000000000b11d0a0597e5a3c6 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable > 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 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. On Thu, Nov 21, 2019 at 2:05 AM Toke H=C3=B8iland-J=C3=B8rgensen wrote: > 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 - > (retval << 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 > > --000000000000b11d0a0597e5a3c6 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
> In theory, this ought to produce a histogram of sojou= rn times (in
> microseconds):
> bpftrace -e 'kretprobe:code= l_skb_time_func { @sojourn =3D lhist((nsecs - (retval << 10))/1000, 0= , 100000, 1000); }'

Thanks for the tips!

> Can't g= et the CoDel drop mechanism to trigger on my system at all,
> though = (a laptop running on iwl). I guess because there's queue
> backpr= essure to userspace first?

What's the tcp_congestion_control in = your system? Maybe it is BBR that prevents bufferbloat.

> It woul= d be interesting to see if it works for you, assuming you can get
> b= pftrace 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.


On Thu, Nov 21, 2019 at 2:05 AM Toke H=C3=B8i= land-J=C3=B8rgensen <toke@redhat.com<= /a>> wrote:
K= an Yan <kyan@google= .com> 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 = - (retval << 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

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