Making iptables probability more granular in kube-proxy. #83599
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Until now, iptables probabilities had 5 decimal places of granularity. That meant that probabilities would start to repeat once a Service had 319 or more endpoints. This doubles the granularity to 10 decimal places, ensuring that probabilities will not repeat until a Service reaches 100,223 endpoints.
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iptables apparently uses "a granularity of 1/2147483648" or ~4.65^(-10) https://manpages.debian.org/unstable/iptables/iptables-extensions.8.en.html I'll give an LGTM since it checks out. /lgtm |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: freehan, robscott The full list of commands accepted by this bot can be found here. The pull request process is described here
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Oct 16, 2019
Making iptables probability more granular in kube-proxy.
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What type of PR is this?
/kind bug
What this PR does / why we need it:
Until now, iptables probabilities generated by kube-proxy had 5 decimal places of granularity. That meant that probabilities would start to repeat once a Service had 319 or more endpoints resulting in poor distribution. This doubles the granularity to 10 decimal places, ensuring that probabilities will not repeat until a Service reaches 100,223 endpoints.
I tested this out with 10k endpoints running on a 150 node Kubernetes cluster. I've included some of the generated iptables output before and after this change in a Gist.
Does this PR introduce a user-facing change?:
/sig network
/cc @freehan