On Tue, Nov 7, 2017 at 4:26 PM, Stephen Hemminger <step...@networkplumber.org> wrote: > On Tue, 7 Nov 2017 12:59:33 -0800 > Dave Taht <dave.t...@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 the kernel patchset you are commenting on, this was the case. There was no way to send via an old iproute2 a jitter or delay value that would trigger sending the new attributes, although the old api has severe rounding errors as you get down to a few us. I just sent a kernel v2 that always sends the old and new attributes. >For iproute2 that means send both new and old versions. This, in the iproute2 patchset, didn't, as I assumed new versions of iproute2 would only be used with newer kernels. I'll respin that. I did want to somehow, one day, obsolete ticks, but I guess that is not possible. -- Dave Täht CEO, TekLibre, LLC http://www.teklibre.com Tel: 1-669-226-2619
