Page History

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• 2022-09-02 krowe: sysctl -a | grep <10Gb NIC> between naasc-vs-3/naasc-vs-5 and naasc-vs-4 are different
  
  • naasc-vs-4 has entries for VLANs 101 and 140 while naasc-vs-3 and naasc-vs-5 have entries for VLANs 192 and 96.
• 2022-09-02 krowe: sysctl -a on naasc-vs-4 and naasc-vs-5 and found many questionable differences
  • naasc-vs-4: net.iw_cm.default_backlog = 256
    • Is this because the IB modules are loaded?
  • naasc-vs-4: net.rdma_ucm.max_backlog = 1024
    • Is this because the IB modules are loaded?
  • naasc-vs-4: sunrpc.rdma*
    • Is this because the IB modules are loaded?
  • naasc-vs-4: net.netfilter.nf_log.2 = nfnetlink_log
    • nfnetlink is a module for packet mangling.  Could this interfere with the docker swarm networking?
• 2022-09-06 krowe: ethtool -k <NIC> for naasc-vs-3/naasc-vs-5 are very different from naasc-vs-4.
  
  • hw-tc-offload: off vs hw-tc-offload: on
  • rx-gro-hw: off vs rx-gro-hw: on
  • rx-vlan-offload: off vs rx-vlan-offload: on
  • rx-vlan-stag-hw-parse: off vs rx-vlan-stag-hw-parse: on
  • tcp-segmentation-offload: off vs tcp-segmentation-offload: on
  • tx-gre-csum-segmentation: off vs tx-gre-csum-segmentation: on
  • tx-gre-segmentation: off vs tx-gre-segmentation: on
  • tx-gso-partial: off vs x-gso-partial: on
  • tx-ipip-segmentation: off vs tx-ipip-segmentation: on
  • tx-sit-segmentation: off vs tx-sit-segmentation: on
  • tx-tcp-segmentation: off vs tx-tcp-segmentation: on
  • tx-udp_tnl-csum-segmentation: off vs tx-udp_tnl-csum-segmentation: on
  • tx-udp_tnl-segmentation: off vs tx-udp_tnl-segmentation: on
  • tx-vlan-offload: off vs tx-vlan-offload: on
  • tx-vlan-stag-hw-insert: off vs tx-vlan-stag-hw-insert: on
• 2022-09-15 krowe: The VM Hosts have different 10Gb network cards
  • naasc-vs-2 uses a Solarflare Communications SFC9220
  • naasc-vs-3 uses a Solarflare Communications SFC9020
  • naasc-vs-4 uses a Broadcom BCM57412 NetXtreme-E
  • naasc-vs-5 uses a Solarflare Communications SFC9020

I found an articles suggesting that GRO can make traffic slower when it is enabled.  I see that rx-gro-hw is enabled on naasc-vs-4 but disabled on naasc-vs-2, 3, and 5.  You can see this with ethtool -k em1 | grep gro. So I disabled it on naasc-vs-4 with ethtool -K em1 gro off and iperf3 tests now show about 2Gb/s both directions!!! I found articles suggesting that GRO can make traffic slower when it is enabled, especially when using vxlan which Docker Swarm uses.

• GRO = Generic Receive Offload.  It is hardware on the physical NIC.  GRO is an aggregation technique to coalesce several receive packets from a stream into a single large packet, thus saving CPU cycles as fewer packets need to be processed by the kernel.
• https://bugzilla.redhat.com/show_bug.cgi?id=1424076
• https://access.redhat.com/solutions/20278
• https://techdocs.broadcom.com/us/en/storage-and-ethernet-connectivity/ethernet-nic-controllers/bcm957xxx/adapters/Tuning/tcp-performance-tuning/nic-tuning_22/gro-generic-receive-offload.html
• https://techdocs.broadcom.com/us/en/storage-and-ethernet-connectivity/ethernet-nic-controllers/bcm957xxx/adapters/Tuning/ip-forwarding-tunings/nic-tuning_48.html
• https://techdocs.broadcom.com/us/en/storage-and-ethernet-connectivity/ethernet-nic-controllers/bcm957xxx/adapters/Tuning/tcp-performance-tuning/os-tuning-linux.htmlAfter disabling rx-gro-hw, I no longer see TCP Retransmission or TCP Out-Of-Order packets when tracing the iperf3 test from na-arc-3 to na-arc-2.

So I disabled it on naasc-vs-4 with ethtool -K em1 gro off and iperf3 tests now show about 2Gb/s both directions!!!

References

• Prepare offline infrastructure from the scratch (Describes docker swarm setup)
• file:///tmp/ALMA%20Offline%20Software%20Test_Deployment%20Concept(2).pdf