perfSONAR User Q&A and Other Discussion

[Brian Tierney <>]

also see: https://fasterdata.es.net/host-tuning/packet-pacing/

On Mon, May 15, 2017 at 7:02 AM, Uhl, George D. (GSFC-423.0)[SGT INC] <> wrote:

Hi Arman,

Make sure the FQ is enabled in the kernel:

http://man7.org/linux/man-pages/man8/tc-fq.8.html

George

From: <> on behalf of Arman Mohsin <>
Date: Sunday, May 14, 2017 at 4:46 PM
To: Brian Tierney <>
Cc: "" <>, "" <>, "" <>, "" <>
Subject: [perfsonar-user] Re: Iperf3 + bandwidth for TCP

But --fq-rate is not limiting my bandwidth for example to 300mbit as you can see in the following example. 

iperf3 -c $SERVER_ADDRESS  --fq-rate 300M -p $PORT -t $TIME -i $INTERVAL -C, --linux-congestion cubic -Z 

The output at the server end is

[ ID] Interval           Transfer     Bandwidth

[  5]   0.00-1.00   sec   110 MBytes   919 Mbits/sec                  

[  5]   1.00-2.00   sec   116 MBytes   976 Mbits/sec                  

[  5]   2.00-3.00   sec   122 MBytes  1.03 Gbits/sec                  

[  5]   3.00-4.00   sec   117 MBytes   985 Mbits/sec                  

[  5]   4.00-5.00   sec   127 MBytes  1.06 Gbits/sec                  

[  5]   5.00-5.04   sec  5.23 MBytes  1.00 Gbits/sec                  

- - - - - - - - - - - - - - - - - - - - - - - - -

Test Complete. Summary Results:

[ ID] Interval           Transfer     Bandwidth

[  5]   0.00-5.04   sec  0.00 Bytes  0.00 bits/sec                  sender

[  5]   0.00-5.04   sec   597 MBytes   994 Mbits/sec                  receiver

CPU Utilization: local/receiver 1.3% (0.1%u/1.2%s), remote/sender 0.0% (0.0%u/0.0%s

On Sun, May 14, 2017 at 9:18 PM, Brian Tierney <> wrote:

-b works for both TCP and UDP, but --fq-rate works much better for TCP on CentOS7/Debian8 based hosts, as it does kernel-level pacing, not user-level pacing.

On Sat, May 13, 2017 at 7:54 PM, Arman Mohsin <> wrote:

Hi Brian,

Hope all is well. Does the iperf3 -c -b option limit bandwidth for TCP as well or is it ONLY for UDP? I tried to read the documentation in the man page but it is a bit confusing. In the earlier versions of iperf the -b option is used to test only UDP but I am not sure if it supports in the latest version (iperf3)

Regards,

Arman

--

Brian Tierney, http://www.es.net/tierney
Energy Sciences Network (ESnet), Berkeley National Lab
http://fasterdata.es.net

--

Brian Tierney, http://www.es.net/tierney
Energy Sciences Network (ESnet), Berkeley National Lab
http://fasterdata.es.net