Timing test going bad causing audio (playback) not sounding good

Asterisk 18.17.1
cat /sys/devices/system/clocksource/clocksource0/current_clocksource
centos 7

 timing test
Attempting to test a timer with 50 ticks per second.
Using the 'timerfd' timing module for this test.
It has been 1000 milliseconds, and we got 48 timer ticks

can not seem to find the reason for it being off set like this !
any ideas i might of missed!
tried changing to acpi_pm or hpet did not help !