Zack's Kernel News

Zack's Kernel News

Article from Issue 211/2018
Author(s):

Improving Netfilter Efficiency; Protecting Memory from Malicious Modification; and Speeding Up Workarounds for Intel Security Flaws.

Improving Netfilter Efficiency

Netfilter has some speed issues. Speed is always a focus of Linux development, but recent workarounds for widespread Intel hardware security flaws have resulted in significant slowdowns in the kernel. So lately, there's been even more incentive to improve speed wherever possible.

Netfilter is a generic kernel tool that allows system administrators to perform a wide array of operations on data packets moving through a network. However, as Imre Palik pointed out recently, netfilter was implemented with flexibility in mind, rather than efficiency. Even when a system performs no operations at all on network packets, simply hitting the netfilter hooks can slow things down a lot.

Imre posted a patch to address this issue. His idea was that if netfilter wasn't being used, then the kernel shouldn't hit its code at all. This would eliminate the slowdown. Of course, for systems that did use netfilter, the slowdown would remain. And this proved to be the big stumbling block for his patch.

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