I don't have much expertise in iperf3 so need to defer to those that do.
>From a 2.0.11 perspective the limits tend to be the write syscall and the
timestamp syscall. It might be interesting to compile the latest 2.0.11
alpha from sourceforge and use the -e (for enhanced reports) to see if
write syscalls are getting enobuffs from the kernel. The write err counter
shows this. If you don't care about latency of jitter and the system
supports itimers, the timestamp sycall could be avoided.
Bob
On Friday, February 2, 2018, Fran Terlingo (fterling) <fterl...@cisco.com>
wrote:
> IPerf Experts,
>
>
>
> I am performing tests between an iPerf 3.1.3 client running on a Linux
> Ubuntu Virtual machine on a VMware ESX host and a similar setup with the
> iPerf 3.1.3 server VM running on a separate ESX server. The ESX servers
> have 10 Gig NICs with plenty of CPU and both connect to a network with a 40
> Gig core. I am able to drive 10 Gbps linerate bandwidth when running iPerf
> “TCP” flows between the client and server. However, the most I can get when
> running a “UDP” test is roughly 5.5 Gbps transmission rate. I actually
> tweaked a couple of iPerf parameters to increase the transmission rate that
> ultimately got me to 5.5 Gbps -- but that is all I can get so far. It
> doesn’t look like the VMs running iPerf are CPU bound so it must be the
> iPerf UDP settings are not optimized.
>
>
>
> Can someone provide guidance on the optimal iPerf settings to get the
> maximum transmission rate when using a UDP flow ??
>
>
>
> Side question: When running iPerf 3.1.3, I was not able use the "-u" flag
> on the server as it stated this was an invalid argument. I also tried
> changing the listening port as well with no luck. I was able to have the
> client set the UDP test and the server was able to accept the UDP test from
> the client. I just can’t set the options on the server side of iPerf 3.1.3
> the way I can with the 2.x releases. I'm not sure if this is something on
> my end or if this is expected behavior. I also need to change the port the
> server listens on and can't get that working when using the “-p” flag on
> the server nor when I try to set the server side port on the client.
>
>
>
> Sorry, just a few more questions. I see there is a way to set the TOS with
> the "-S" flag. Is there a way to set the DSCP (Diffserv) marking in the
> packet instead of TOS ?? Lastly, is there a way to set the MTU size of the
> frame generated by iPerf or possibly even use jumbo frames ??
>
>
>
> Thanks,
>
> Fran
>
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