Increase Bandwidth for TCP to 1MB on Photon OS

[EleanorRigby]

• Set net.ipv4.tcp_limit_output_bytes to 1048576
• Photon's default kernel value for net.ipv4.tcp_limit_output_bytes is 256K compared to 1MB in Ubuntu

GOSS Kernel param entry for this will be added in #307

Run result on powered on VM

root [ /home/capv ]# cat /etc/os-release
  NAME="VMware Photon OS" 
  VERSION="3.0"
  ID=photon 
  VERSION_ID=3.0
  PRETTY_NAME="VMware Photon OS/Linux"
  ANSI_COLOR="1;34"
  HOME_URL="https://vmware.github.io/photon/"
  BUG_REPORT_URL="https://github.com/vmware/photon/issues"
root [ /home/capv ]# sysctl -a | grep net.ipv4.tcp_limit_output_bytes
  net.ipv4.tcp_limit_output_bytes = 1000000000
root [ /home/capv ]#

/assign : @codenrhoden

[k8s-ci-robot]

Hi @EleanorRigby. Thanks for your PR.

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[vincepri]

/ok-to-test
/assign @dims @detiber

[detiber]

Not sure if I have enough context here, is this something that we should also look to the Photon team to change in their defaults?
Travis might have some thoughts around this as well.
/assign @codenrhoden

[codenrhoden]

I believe the Photon team is sticking what is default in the base kernel, which changes in kernel 5.0. But this handles the other cases. I'll ping someone who can chime in more.

[codenrhoden]

Is there anything we need to do to have the GOSS kernel param verification check this as well?

I know this would be a new/diff case because it's distro-specific.

[EleanorRigby]

It will be added to PR #307 if this merges first. Else later to PhotonOS kernel param section in goss-vars.yml

[suezzelur]

Not sure if I have enough context here, is this something that we should also look to the Photon team to change in their defaults?
Travis might have some thoughts around this as well.
/assign @codenrhoden

Upstream recommendation for 4.19 kernel is 256kB, the default changed with code changes in 5.0 kernel version like @codenrhoden mentioned. The recommendation usually covers multiple use cases, but like in the change here it can always be tuned to conform to specific requirements.

[codenrhoden]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: codenrhoden, EleanorRigby

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