Interrupts : request_percpu_irq function

[priyaranjan]

I was reading about request_irq() function. We have another variant of
this function known as request_percpu_irq(). Can any one explain me
the usage of this function? and how it is different that the
traditional request_irq().

I also couldn't find a single driver using this function though this
has been extensively used in architecture specific files especially
the timers and the watchdog.

Also it would be great, if someone can point out any document/link
where I can find the description.
I failed to find it from Linux kernel documentation.

Regards,
Priyaranjan