Audio doesn't use setitimer()-driven sleeping. It's interrupt-driven, not timer-driven.
Yes, the driver is interrupt driven, but the driver interrupt handler is only responsible for getting the data off the card's FIFO and storing it in memory. (i.e., initialing a DMA transfer.) It doesn't do anything with the audio data itself, except pass it on to user space. Won't HZ make a difference to the user application code which must wake up to do something with this audio data? Hence the need for SCHED_FIFO and the like.. Steve
