Hi Bruce thanks for giving time on this issue.

I am working on an embedded system with imx50.
Server i'm using is RaspberryPi. Both the machines are connected on same
network.

Yes the system is a bit loaded. So this might be the reason.
But if I reduce the window size then bandwidth also reduces and the time
interval issue disappears.

But with bandwidth of ~45M (which is the max it is showing) then it starts
giving time interval issues.

One more thing, I tried with iperf as well and its not giving any such
issues on same machine with same server.

On Thu, May 3, 2018 at 11:49 PM, Bruce A. Mah <b...@es.net> wrote:

> If memory serves me right, Nikita Gupta wrote:
> > Hi team,
> >
> > While checking network performance using iperf3, I'm facing interval
> > issue at client end. Below are the logs:
> >
> > [  5]   0.00-1.05   sec  11.2 MBytes  88.7 Mbits/sec    0   42.4
> > KBytes
> > [  5]   1.05-2.01   sec  10.0 MBytes  88.2 Mbits/sec    0   42.4
> > KBytes
> > [  5]   2.01-3.07   sec  11.2 MBytes  88.4 Mbits/sec    0   42.4
> > KBytes
> > [  5]   3.07-4.05   sec  10.3 MBytes  88.5 Mbits/sec    0   42.4
> > KBytes
> > [  5]   4.05-5.11   sec  11.2 MBytes  88.6 Mbits/sec    0   42.4
> > KBytes
> > [  5]   5.11-6.06   sec  10.0 MBytes  88.7 Mbits/sec    0   42.4
> > KBytes
> > [  5]   6.06-7.07   sec  10.7 MBytes  89.0 Mbits/sec    0   42.4
> > KBytes
> > [  5]   7.07-8.02   sec  10.0 MBytes  88.6 Mbits/sec    0   66.5
> > KBytes
> > [  5]   8.02-9.09   sec  11.1 MBytes  86.8 Mbits/sec    0    112
> > KBytes
> > [  5]   9.09-10.06  sec  10.0 MBytes  85.7 Mbits/sec    0    112
> > KBytes
> > - - - - - - - - - - - - - - - - - - - - - - - - -
> > [ ID] Interval           Transfer     Bitrate         Retr
> > [  5]   0.00-10.06  sec   106 MBytes  88.1 Mbits/sec    0
> sender
> > [  5]   0.00-10.12  sec   106 MBytes  87.6 Mbits/sec
> > receiver
> >
> > I checked github bug #125 which was addressing this specific issue. But
> > no help.
> > I have tried iperf3.0.5, iperf3.1, iperf3.3, iperf3.5. In all versions,
> > I'm getting the same issue.
> >
> > P.S. Server(with same iperf3 version) provides result as expected with 1
> > sec time interval, but client provides data at different time intervals
> > in every iteration.
> > Kindly look into the issue and do let me know if m missing something.
>
> What are the command line arguments you are using (both client and
> server side, sanitize them as necessary0?  Also could you say something
> about the environment you're running in?  In particular, what OS and
> hardware on the client and server, and what kind of network path are you
> going over?
>
> I rarely see issues like this (where the statistics printing intervals
> are not aligned to whole second boundaries) in the middle of a test,
> although it's been known to happen at the end of a test, for conditions
> that only happen at the end of a test.
>
> It seems like the timers within iperf3 that control when statistics and
> computed and printed aren't firing when they're supposed to.  On my
> laptop (MacBook Pro) this happens close enough to the correct time that
> the timestamps appear to be exactly aligned to whole second boundaries
> (they're not, but close enough given the precision of printing the
> values in the output).  This situation could happen on slow hardware
> (some kind of embedded system?), on a virtual machine, or on a system
> that is very heavily loaded.  We would need some more information to
> determine which of this is the case (or whether it's something
> completely different).
>
> Bruce.
>
>
>
>
>


-- 
Regards,
Nikita Gupta
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