1. Further, disabling interrupts is often deemed too expensive to be practical. 2. However, disabling interrupts has numerous downsides. 3. Prior to kernel version 2.6, Linux disabled interrupt to implement short critical sections. 4. RTOSs implementing the unified architecture solve the problem by simply disabling interrupts while the internal catalogue is updated. 5. In multiprocessor systems, it is usually impossible to disable interrupts on all processors at the same time. 6. If an ISR is involved, the only way to ensure exclusive access to common variables is to disable interrupts . 7. For example, the Z80 / Z180 family disables interrupts once an interrupt is serviced by an interrupt service routine. 8. If the I / O registers are swapped out, it is also necessary to disable interrupts via an STI instruction. 9. When there are multiple instructions which must be completed without interruption, a CPU instruction which temporarily disables interrupts is used. 10. Setting or clearing this mask may be faster than accessing an interrupt mask register ( IMR ) in a PIC or disabling interrupts in the device itself.
