As I know it probably do not any effect on IRQ routine. Or do it?
No, it does not. Well, it does, but that depends.
Before entering an interrupt routine the interrupt disable flag (
I) is set, preventing the CPU from accepting other interrupts so it can setup the environment needed to do its job without being interrupted again. Basically an implied
SEI, creating a semaphore (lock) around the (start of) the interrupt routine.
It is (as always) good practice to keep locked sections as short as possible. So as soon as a routine has established itself and gathered whatever data is necessary to be collected undisturbed, for example detecting the source, it should enable interrupts again. After this, other interrupt sources can get served in parallel.
Of course, all of this depends on the structure of the whole system, the program(s) in control, the number of concurrent interrupts and the like.
Without knowing more of either it's impossible to say if there are effects or not.