FreeRTOS in motor control application

I am going to use the FreeRTOS for induction motor control application. This application requires to implement part of the control software in interrupt service routine associated with end of the A/D conversion.

Due to this fact I would like to know whether in case the interrupt service routine (ISR) is executed the scheduler is inhibited or whether it is possible that the ISR is interrupted by the scheduler. Then I would like to know whether the FreeRTOS offers some services for measurement of time spent by execution of the ISR. Thanks in advance for your answer.

ISRs might only be interrupted by higher prio ISRs if interrupt nesting is supported by your MCU and enabled.
But for very small periods of time interrupts might be disabled (globally) by FreeRTOS.
It is possible to exclude ISRs from being covered by FreeRTOS.
See the docs and e.g. this topic and/or the forum for details concerning the latter somewhat special use case.