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smm_latency

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From my experience, it's very difficult to achieve low latency on modern Intel processors (after Sandy Bridge) because of SMI interrupts:

https://en.wikipedia.org/wiki/System_Management_Mode

Some of the SMI interrupts can be disabled by smictrl, but there usually remains an interrupt every 10-20 seconds with 100+ microsecond latency. See plot here:

http://wiki.linuxcnc.org/cgi-bin/wiki.pl?FixingSMIIssues

SMI interrupts are used for fan / thermal region control and cannot be fully disabled.