https://wiki.asterisk.org/wiki/display/AST/Timing+Interfaces

List existing Asterisk modules, start the Asterisk CLI and run a timing test:

ls /usr/lib64/asterisk/modules

asterisk -vvvvvvvvr

*CLI> module show like timing

*CLI> timing test

res_timing_timerfd is probably best for use in a virtual machine.

Modify order of timing sources:

vim /etc/asterisk/modules.conf

[modules]
preload => res_timing_timerfd.so
preload => res_timing_dahdi.so
preload => res_timing_pthread.so