I am running FreeRTOS on Cortex R5 with TICKLESS_IDLE enabled.

And I have a loop like this in my code:

while (cond) { do_something(); vTaskDelay(1); }

Now, when vTaskDelay is called the current thread goes to sleep, and the thread wakes up and returns after vTaskDelay at variable times from 3 to 24 seconds. Not micro or milli seconds, vTaskDelay with 1 tick resumes after 3 to 24 seconds.

Any suggestions on how to go about debugging or hints will be greatly appreciated.

Did you get the tickless idle code from us? (by which I mean from the official FreeRTOS zip file download) I don't think we provide this for Cortex R5 but could be wrong.