Add net.ipv4.tcp_rmem and net.ipv4.tcp_wmem into safe sysctl list about kubernetes HOT 10 OPEN

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/sig node

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/sig network
/cc @thockin

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Hey @SataQiu, I would like to take this up after triage-accepted label. Thanks

/assign

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@nikzayn I had started working on this yesterday, but I'm fine passing the ball to you. Please take a look at my changes, perhaps some of them are worth porting over to your PR. Thanks.

https://github.com/kubernetes/kubernetes/compare/master...mauri870:kubernetes:feature/sysctl-tcp-rmem-wmem?expand=1

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Related work for net.ipv4.tcp_keepalive_time at #118846 can be used as inspiration as well.

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Thanks a lot @mauri870 my bad I didn't know you were working. I should have to wait for someone to assign from next time. Thanks for passing the ball. Definitely, I will take a look and after a successful build pass will push the respective changes.

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Thanks a lot @mauri870 my bad I didn't know you were working. I should have to wait for someone to assign from next time. Thanks for passing the ball. Definitely, I will take a look and after a successful build pass will push the respective changes.

No worries, it's my fault for not assigning the issue to myself earlier. I'm glad you were able to work on it.

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Thanks a lot @mauri870 my bad I didn't know you were working. I should have to wait for someone to assign from next time. Thanks for passing the ball. Definitely, I will take a look and after a successful build pass will push the respective changes.

No worries, it's my fault for not assigning the issue to myself earlier. I'm glad you were able to work on it.

Thanks, I have made the changes. You can check that out. Do checkout of If I am missing anything. Thanks!!

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What is the typical TCP RTT between those Cassandra nodes?

BDP (bits) = bandwidth (bits/second) * RTT (seconds)
sudo sysctl -w net.ipv4.tcp_rmem="4096 87380 $MaxExpectedPathBDP"
See https://cloud.google.com/compute/docs/networking/tcp-optimization-for-network-performance-in-gcp-and-hybrid

TCP memory is not that safe per https://lpc.events/event/16/contributions/1212/

Potentially a low priority job can hog all the available TCP memory and starve the high priority jobs collocated with it. Indeed we have seen production incidences of low priority jobs negatively impacting the network performance of collocated high priority jobs.

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