VILLASnode/doc/Tuning.md

Tuning

Operating System and Kernel

For minimum latency several kernel and driver settings can be optimized. A PREEMPT_RT patched Linux kernel is recommended. Precompiled kernels for Fedora can be found here: http://ccrma.stanford.edu/planetccrma/software/

• Map NIC IRQs => see setting affinity

• Map Tasks => see setting affinity

  • Kernel command line: isolcpus=[cpu_number]

• Increase priority of server task (nice(2)) => see setting priority

• Increase socket priority

• Configure NIC interrupt coalescence with ethtool:

  $ ethtool -C|--coalesce devname [adaptive-rx on|off] [adaptive-tx on|off] ...

• Configure NIC kernel driver in /etc/modprobe.d/e1000e.conf:

  More conservative interrupt throttling for better latency

  https://www.kernel.org/doc/Documentation/networking/e1000e.txt

  option e1000e InterruptThrottleRate=

Hardware

This are some proposals for the selection of appropriate server hardware:

• Server-grade CPU: Intel Xeon

  • A multi-core systems allows parallization of send/receive paths.

• Server-grade network cards: Intel PRO/1000

  • These allow offloading of UDP checksumming to the hardware