[tor-talk] Practical deanonymization using CPU load covert channels

[some_guy123 at Safe-mail.net]

> With two computers connected via Ethernet through a switch, I would
> normally get ping timings of around 250 microseconds.
> However, when the computer being pinged was pegged at 100% CPU on all
> cores, _ping latency would drop to about 170 microseconds._

This is probably caused by power management. Depending on the CPU, C3 wake latency can be >35us, C6 wake latency >100us.

You should try to disable these C-states in the BIOS or kernel:
https://access.redhat.com/articles/65410
http://www.breakage.org/2012/11/14/processor-max_cstate-intel_idle-max_cstate-and-devcpu_dma_latency/