Booming usage of Linux in embedded environments is creating an on-going demand to use this general-purpose operating system in industrial control devices and other fields, previously reserved for classic real-time operating systems. Talk covers success story of Linux based embedded ARM system controlling weight dosing in injection-molding process (plastics industry). Practical, universal (applicable to most SoCs), open-source solution is presented: embedded Linux, process control application and responsive, QT based GUI. Emphasis is put on problems occurring and solutions: advantages and disadvantages of RT-PREEMPT and Xenomai from a practical point of view. Presentation includes latency measurement results and techniques.