perfSONAR User Q&A and Other Discussion

[Scot Colburn <colburn@ucar.edu>]

Hi Perfsonar gurus!

Why does the perfsonar-toolkit installation turn off TSO?

Our 10GE Debian perfsonars connected back-to-back get only 3-4 Gbps performance on 1500 byte MTUs after installing the perfsonar-toolkit. We get good 9.5 Gbps iperf3 TCP performance until the perfsonar-toolkit is installed. We can restore 9.5 Gbps performance by enabling TSO on the transmitting 10GE interface, like this:

root@debian:/home/ansible-mgmt# ethtool -K enp1s0f1 tso on
root@debian:/home/ansible-mgmt# ethtool -k enp1s0f1 | grep tcp-segmentation-offload
tcp-segmentation-offload: on

root@debian:/home/ansible-mgmt# ethtool --driver enp1s0f1
driver: i40e
version: 6.1.0-31-amd64
firmware-version: 9.00 0x8000d299 1.3256.0
expansion-rom-version:
bus-info: 0000:01:00.1
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: yes

Why is TSO turned off, anyway? I recall there used to be problems with TSO. Are there still? Are we covering up some other problem by turning it on?

--Scot

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Scot Colburn

Network Engineer NSF NCAR/UCAR/NETS/FRGP

303-497-2452