On Tue, Sep 20, 2016 at 3:03 PM, Dave Täht <dave@taht.net> wrote:

> Groovy. I note that I am really fond of the linux "fdtimer" notion for
> tickers, we use that throughout the high speed stats gathering code in
> flent.
>
> I'd really like a voip or ping tool that used those, and I've always
> worried about iperf's internal notion of a sampling interval.
>
> On 9/20/16 3:00 PM, Aaron Wood wrote:
> > I modified iperf3 to use a 1ms timer, and was able to get things much
> > smoother.  I doubt it's as smooth as iperf3 gets on Linux when fq pacing
> > is used, but it's a big improvement vs. the nice small buffers in
> switches.
>

Thanks!

For rates of <1000 packets per second, the 1ms timer I put in will give
something like that (it fires every ms, but that's just a check for sending
or not).  If you want to use it to model a 120pps flow of 64-byte packets:

iperf3 -c <host> -u -l 64 -b 61440

And then it will pace those out at roughly every 80ms (just verified this
on my box)

-Aaron