Re: [PATCH net-next 0/3] netem: add nsec scheduling and slot feature

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue,  7 Nov 2017 12:59:33 -0800
Dave Taht <dave.taht@gmail.com> wrote:

> This patch series converts netem away from the old "ticks" interface and
> userspace API, and adds support for a new "slot" feature intended to
> emulate bursty macs such as WiFi and LTE better.
> 
> Dave Taht (3):
>   netem: convert to qdisc_watchdog_schedule_ns
>   netem: add uapi to express delay and jitter in nanosec
>   netem: support delivering packets in delayed time slots
> 
>  include/uapi/linux/pkt_sched.h |  10 +++
>  net/sched/sch_netem.c          | 144 ++++++++++++++++++++++++++++++++---------
>  2 files changed, 125 insertions(+), 29 deletions(-)
> 

Dave, thanks for the patch.
One issue is that it needs to keep binary compatibility both for kernel and iproute.
That means that users of new kernel should be able to use old versions of iproute
without any visible impact (and vice versa).

For the kernel, that means if new attributes are not present the old attributes
would be used. For iproute2 that means send both new and old versions.