[Cerowrt-devel] Problems testing sqm

[Aaron Wood]

I've done the same setup in the past with my 3800, and htb limits just fine
to 10Mbps even when used with gigabit lab links.

So I think that, for whatever reason, htb just isn't functioning.

Dumping the qdiscs setup and stats using tc should make it clearer as to
what the state of things actually is.

-Aaron
On Sat, Oct 24, 2015 at 10:25 Sebastian Moeller <moeller0 at gmx.de> wrote:

> Hi David,
>
>
> On Oct 24, 2015, at 18:34 , David P. Reed <dpreed at reed.com> wrote:
>
> > Not trying to haggle.
>
>         Sorry, I was a bit to grumpy for unrelated reasons.
>
> > Just pointing out that this test configuration has a very short RTT.
> maybe too short for our SQM to adjust to.
>
>         That could be, but I believe people have tested fq_codel and sqm
> with similar setups and generally got dozens of milliseconds induced delay,
> not multiple seconds. So sure sqm might not for the best thing but it
> should deliver a reasonable compromise. Now, I believe Toke has a test bed
> where he can vary the transmission delay so he might know already whether
> sqm has issues with 1GE lans.
>
> Best Regards
>         Sebastian
>
> >
> > On Oct 24, 2015, Sebastian Moeller <moeller0 at gmx.de> wrote:
> > Hi David,
> >
> > On Oct 24, 2015, at 00:53 , David P. Reed <dpreed at reed.com> wrote:
> >
> > In particular, the DUT should probably have no more than 2 packets of
> outbound queueing given the very small RTT. 2xRTT is the most buffering you
> want in the loop.
> >
> > Let’s not haggle about the precise amount of queueing we deem
> acceptable, as long as we all agree that >= 2 seconds is simply not
> acceptable ;) (the default sqm will approximately limit the latency under
> load increase (LULI) to roughly twice the target or typically 10 ms; note
> that this LULI only applies to unrelated flows). The exact number of queued
> packets seems to correlate with the beefiness of the DUT, the beefier the
> fewer packets should work, wimpier devices might need to batch some
> processing up, resulting in higher LULI…
> >
> > Best Regards
> > Sebastian
> >
> >
> > On Oct 23, 2015, Richard Smith <smithbone at gmail.com> wrote:
> > On 10/23/2015 02:41 PM, Michael Richardson wrote:
> > Richard Smith <smithbone at gmail.com> wrote:
> > My test setup:
> >
> > Laptop<--1000BaseT-->DUT<--1000baseT-->Server
> >
> > So, given that the DUT is the only real constraint in the network, what
> > do you expect to see from this setup?
> >
> > Given that the probably DUT can't forward at Gb/s, and it certainly can't
> > shape anything, it's gonna drop packets, and it's probably gonna drop
> them in
> > Rx, having overrun the Rx-queue (so tail-drop). If there is too much ram
> > (bufferbloated), then you'll see different results...
> >
> > Setting ingress/egress to 10Mbit/s I expected to see the speed
> > measurements bounce around those limits with the ping times staying in
> > the low double digits of ms. What I saw however, was the data rates
> > going well past 10Mbit limit and pings up to 2000 ms.
> >
> > This is what I've seen in prior rrul testing using a the 50/10 cable
> > link at our office and my 25(ish)/6 link at my apartment and a well
> > connected server on the net. That however was using QoS and not SQM.
> >
> > Its that a reasonable expectation?
> >
> > -- Sent with K-@ Mail - the evolution of emailing.
> >
> > Cerowrt-devel mailing list
> > Cerowrt-devel at lists.bufferbloat.net
> > https://lists.bufferbloat.net/listinfo/cerowrt-devel
> >
> >
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>
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