About the suggested sysctl.conf settings: I think you'd also need to adjust net.core.rmem_max and net.core.wmem_max in order for the net.ipv4.tcp_rmem and net.ipv4.tcp_wmem settings to be effective.
Furthermore it couldn't hurt to increase net.core.netdev_max_backlog, which is the maximum number of packets queued on the input side, when the interface receives packets faster than kernel can process them.
Regarding the `net.core` parameters. We do modify those, but my assumption (probably wrong) was that the `net.ipv4` changes would override the core configs. I'll take a look and update the post. Good point about `netdev_max_backlog`, I need to read up on that one too.
About the suggested sysctl.conf settings: I think you'd also need to adjust net.core.rmem_max and net.core.wmem_max in order for the net.ipv4.tcp_rmem and net.ipv4.tcp_wmem settings to be effective.
Furthermore it couldn't hurt to increase net.core.netdev_max_backlog, which is the maximum number of packets queued on the input side, when the interface receives packets faster than kernel can process them.