[Rtai] is it necessary to disable cache for some critical hard real-time tasks?

[arethe rtai]

I am a software developer in field of industrial control system. These
systems require hard real-time support, even exact temporal behavior.
The cache is a major source of uncertainty, is it necessary to disable
cache for some critical hard real-time tasks? I am looking forward to
your professional adivce.
3x
regards arethe