netdev - Re: [PATCH net-next] selftests/net: SO

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Message-ID: <CA+FuTSd11kyWjQ9V+TfgCEutzAFCheL=POq7kL0chkObcdk05Q@mail.gmail.com>
Date:   Thu, 23 May 2019 13:33:22 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net-next] selftests/net: SO_TXTIME with ETF and FQ

On Thu, May 23, 2019 at 1:06 PM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
>
> On 5/23/19 9:45 AM, Willem de Bruijn wrote:
> > The SO_TXTIME API enables packet tranmission with delayed delivery.
> > This is currently supported by the ETF and FQ packet schedulers.
> >
> > Evaluate the interface with both schedulers. Install the scheduler
> > and send a variety of packets streams: without delay, with one
> > delayed packet, with multiple ordered delays and with reordering.
> > Verify that packets are released by the scheduler in expected order.
> >
> > The ETF qdisc requires a timestamp in the future on every packet. It
> > needs a delay on the qdisc else the packet is dropped on dequeue for
> > having a delivery time in the past. The test value is experimentally
> > derived. ETF requires clock_id CLOCK_TAI. It checks this base and
> > drops for non-conformance.
> >
> > The FQ qdisc expects clock_id CLOCK_MONOTONIC, the base used by TCP
> > as of commit fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC").
> > Within a flow there is an expecation of ordered delivery, as shown by
> > delivery times of test 4. The FQ qdisc does not require all packets to
> > have timestamps and does not drop for non-conformance.
> >
> > The large (msec) delays are chosen to avoid flakiness.
> >
> >       Output:
> >
> >       SO_TXTIME ipv6 clock monolithic
>
> s/monolithic/monotonic/

Oops. That's actually fixed in the latest version, just not in the
commit message. I'll send a v2 just to update that. Thanks Eric.

Having some trouble with git send-email and gmail today, hence the
email from my google.com account, too.



>
> >       payload:a delay:33 expected:0 (us)
> >
> >       SO_TXTIME ipv4 clock monolithic
> >       payload:a delay:44 expected:0 (us)
> >
> >       SO_TXTIME ipv6 clock monolithic
> >       payload:a delay:10049 expected:10000 (us)
> >
> >       SO_TXTIME ipv4 clock monolithic
> >       payload:a delay:10105 expected:10000 (us)
>
>
> Thanks for the test Willem.
>
> Acked-by: Eric Dumazet <edumazet@...gle.com>
>