Linux Networking Improvements To Mitigate Retpoline Overhead Ready For 4.21 Kernel

Written by Michael Larabel in Linux Networking on 17 December 2018 at 12:03 AM EST. 2 Comments
The recently talked about work to improve/restore Linux networking performance around Retpolines is queued now in net-next for the upcoming Linux 4.21 kernel cycle.

This patch series for the Linux kernel's networking subsystem is about mitigating the Retpoline overhead introduced at the start of the year in order to address the Meltdown CPU security issue.

The Linux networking performance was one of the key areas taking a sizable performance hit from the introduction of "return trampolines" while now that is going to be partially recovered. "Experimental results show that replacing a single indirect call via retpoline with several branches and a direct call gives performance gains even when multiple branches are added - 5 or more...Overall this gives [greater than] 10% performance improvement for UDP GRO benchmark and smaller but measurable for TCP syn flood."

The latest cleaned up version of those patches were merged to the net-next Git tree ahead of the Linux 4.21 kernel merge window that should open in about one week.

Linux 4.21 kernel benchmarks, obviously, will be coming up in the weeks ahead.
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