From: Neal Cardwell <ncardwell@google.com>
To: Aaron Wood <woody77@gmail.com>
Cc: "cerowrt-devel@lists.bufferbloat.net"
<cerowrt-devel@lists.bufferbloat.net>,
Eric Dumazet <edumazet@google.com>,
Yuchung Cheng <ycheng@google.com>
Subject: Re: [Cerowrt-devel] BBR congestion control algorithm for TCP in net-next
Date: Mon, 26 Sep 2016 15:30:13 -0400 [thread overview]
Message-ID: <CADVnQynSJ9Ze2cXL=J21E9EO2QT37s-4NNW7x=XBVAF-4VY4mw@mail.gmail.com> (raw)
In-Reply-To: <CALQXh-OCV5T1=ZczY+=snZfXqY1t7vYEMuMLGbUps0afP8t+Qg@mail.gmail.com>
On Mon, Sep 26, 2016 at 2:47 PM, Aaron Wood <woody77@gmail.com> wrote:
> Dumb question on this: The tcp_bbr_info struct for a socket can be
> inspected at runtime through the ss utility or through a get socket opts
> call, right?
Yes, you can use either approach:
(1) from code you can use TCP_CC_INFO socket option; there is sample
code in the original kernel patch for TCP_CC_INFO:
https://patchwork.ozlabs.org/patch/465806/
(2) from ss: if you download and build the net-next branch of the
iproute2 package:
http://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/log/?h=net-next
then you will get support to print out the main parameters for a BBR
connection, eg:
The patch with BBR support for ss is here:
http://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/commit/?h=net-next&id=2f0f9aef94129643133363b4503468cdccc481cc
As the commit notes, the BBR output looks like:
bbr:(bw:1.2Mbps,mrtt:18.965,pacing_gain:2.88672,cwnd_gain:2.88672)
Hope that helps,
neal
>
> -Aaron
>
> On Sat, Sep 17, 2016 at 11:34 AM, Maciej Soltysiak <maciej@soltysiak.com>
> wrote:
>>
>> Hi,
>>
>> Just saw this: https://patchwork.ozlabs.org/patch/671069/
>>
>> Interested to see how BBR would play out with things like fq_codel or
>> cake.
>>
>> "loss-based congestion control is unfortunately out-dated in today's
>> networks. On
>> today's Internet, loss-based congestion control causes the infamous
>> bufferbloat problem"
>>
>> So, instead of waiting for packet loss they probe and measure, e.g. when
>> doing slow start (here called STARTUP) they don't speed up until packet
>> loss, but slow down before reaching estimated bandwidth level.
>>
>> Cake and fq_codel work on all packets and aim to signal packet loss early
>> to network stacks by dropping; BBR works on TCP and aims to prevent packet
>> loss.
>>
>>
>> Best regards,
>> Maciej
>>
>>
>> _______________________________________________
>> Cerowrt-devel mailing list
>> Cerowrt-devel@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>>
>
>
> _______________________________________________
> Cerowrt-devel mailing list
> Cerowrt-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>
next prev parent reply other threads:[~2016-09-26 19:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-17 18:34 Maciej Soltysiak
2016-09-17 18:53 ` Dave Taht
2016-09-21 9:06 ` Alan Jenkins
2016-09-21 9:39 ` Dave Taht
2016-09-21 10:10 ` Alan Jenkins
2016-09-21 10:15 ` Mikael Abrahamsson
2016-09-21 11:14 ` Alan Jenkins
2016-09-21 11:28 ` Mikael Abrahamsson
2016-09-21 11:19 ` Dave Taht
2016-09-21 11:32 ` Mikael Abrahamsson
2016-09-21 12:40 ` Mikael Abrahamsson
2016-09-21 13:49 ` [Cerowrt-devel] [Bloat] " Alan Jenkins
2016-09-17 20:11 ` [Cerowrt-devel] " Jonathan Morton
2016-09-26 18:47 ` Aaron Wood
2016-09-26 19:30 ` Neal Cardwell [this message]
2016-09-26 19:45 ` Aaron Wood
2016-09-26 21:38 ` Dave Taht
2016-09-26 22:09 ` Aaron Wood
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