Why we use the Linux kernel's TCP stack
>With this scale of attack the Linux kernel is not enough for us. We must work around it...we added a partial kernel bypass feature to Netmap: that's described in this blog post. With this technique we can offload our anti-DDoS iptables to a very fast userspace process.What do they mean by "very fast userspace process"? If you're doing the same thing the kernel would be doing, the userspace process should be strictly slower due to context switches. What costs are they saving on here?