What is the difference between FIQ and IRQ interrupt system?

Question

I want to know the difference between FIQ and IRQ interrupt system in any microprocessor, e.g: ARM926EJ.

Answer 1

It Depends how we design interrupt handlers, as FIQ is at last it may not need one branch instruction, also it has unique set of r8-r14 registers so next time we come back to FIQ interrupt we do not need to push/pop up the stack. Ofcourse it saves some cycles, but again it is not wise to have more handlers serving one FIQ and yes FIQ is having more priority but it is not any reason to say it handles the interrupt faster, both IRQ/FIQ run at same CPU frequency, So they must be running at same speed.