as far as I know, Linux has 'fast interrupts', those that were requested with SA_INTERRUPT flag; fast interrupts are executed with all other interrupts disabled on the current CPU. But how does it differ from the normal interrupt handler behavior (where)?
There is a good write up here:
So the only difference is the one that you mentioned; that fast interrupt handlers execute with all other interrupt handlers disabled, for faster performance.
As of today, you can mostly forget about the
If you have a kernel before 2.6.18, you'll probably won't use it (see Justin's answer).
Today's usage of
Concerning the difference; a normal interrupt can be interrupted by an other interrupt (preemption), a "fast" one on the other hand, can not.