[Cerowrt-devel] BBR congestion control algorithm for TCP in net-next

[Aaron Wood]

I'll hit it from Comcast's ~150Mbps service on the peninsula when I get
home today (with and without sqm)

-Aaron

On Mon, Sep 26, 2016 at 2:38 PM, Dave Taht <dave.taht at gmail.com> wrote:

> I just put a netperf server up in linode's freemont, ca, cloud (kvm
> paravirtualized hardware), with sch_fq enabled, ecn disabled, and bbr
> as the default cc. (reno and cubic are also allowed)
>
> I am curious if y'all hit it with your rrul, tcp_ndown,
> rtt_fair_var_down (vs flent-freemont in the same dc) etc, that you get
> sane results - with and without sqm-scripts moderating your
> connection.
>
> I've always kind of worried that sch_fq would misbehave in a
> virtualized environment, and they seem to do some odd things with
> policing/shaping in their world that I've not sorted out (speeds >
> 200Mbit)
>
> DNS for flent-bbr-west.bufferbloat.net is propagating (both IPv4 and IPv6)
>
> Til then:
> the ipv4 for the thing is: 173 dot 230 dot 156 dot 252
>
> I've put a broad sweep of results up in my github, haven't looked at
> them to a huge extent yet.
>
>
> On Mon, Sep 26, 2016 at 12:45 PM, Aaron Wood <woody77 at gmail.com> wrote:
> > Thanks! And sorry that I missed the sample code in the patch.
> >
> > On Mon, Sep 26, 2016 at 12:30 Neal Cardwell <ncardwell at google.com>
> wrote:
> >>
> >> On Mon, Sep 26, 2016 at 2:47 PM, Aaron Wood <woody77 at 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=2f0f9aef94129643133363b4503468
> cdccc481cc
> >>
> >>   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 at 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 at lists.bufferbloat.net
> >> >> https://lists.bufferbloat.net/listinfo/cerowrt-devel
> >> >>
> >> >
> >> >
> >> > _______________________________________________
> >> > Cerowrt-devel mailing list
> >> > Cerowrt-devel at lists.bufferbloat.net
> >> > https://lists.bufferbloat.net/listinfo/cerowrt-devel
> >> >
> >
> >
> > _______________________________________________
> > Cerowrt-devel mailing list
> > Cerowrt-devel at lists.bufferbloat.net
> > https://lists.bufferbloat.net/listinfo/cerowrt-devel
> >
>
>
>
> --
> Dave Täht
> Let's go make home routers and wifi faster! With better software!
> http://blog.cerowrt.org
>
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