1. 1/9/2016 08:46 1 Priority Model Real-time class 26 25 24 23 22 16 Idle Above Normal Normal Below Normal Lowest Highest 31 Time-critical Dynamic classes 15 Time-critical 14 13 12 11 15 High class 1 Idle 9 8 7 11 Normal class 10 5 4 3 2 6 Idle class Thread Level

2. 1/9/2016 08:46 2 Thread Priority = Process class + level Real-time class 26 25 24 23 22 16 Idle Above Normal Normal Below Normal Lowest Highest 31 Time-critical Dynamic classes 15 Time-critical 14 13 12 11 15 High class 1 Idle 9 8 7 11 Normal class 10 5 4 3 2 6 Idle class Thread Level

3. 1/9/2016 08:46 3 Scheduling  Threads scheduled by executive.  Priority based preemptive scheduling. Interrupts Deferred Procedure Calls (DPC) System and user-level threads

4. 1/9/2016 08:46 4 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts Interrupt Service Routine DPC Routine Device Driver DPC DPC FIFO Queue DPC DPC FIFO Queue user-level threads Interrupts DPC

5. 1/9/2016 08:46 5 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver DPC DPC FIFO Queue DPC DPC FIFO Queue user-level threads Interrupts DPC

6. 1/9/2016 08:46 6 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver DPC DPC FIFO Queue DPC DPC FIFO Queue user-level threads Interrupts DPC

7. 1/9/2016 08:46 7 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver DPC DPC FIFO Queue DPC DPC FIFO Queue user-level threads Interrupts DPC 3 Stop int.. and queue DPC

8. 1/9/2016 08:46 8 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver DPC DPC FIFO Queue DPC DPC FIFO Queue user-level threads Interrupts DPC 3 Stop int.. and queue DPC

9. 1/9/2016 08:46 9 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver 3 Stop int.. and queue DPC DPC DPC FIFO Queue DPC DPC FIFO Queue 4 Task level drops and DPC can execute user-level threads Interrupts DPC

10. 1/9/2016 08:46 10 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver 3 Stop int.. and queue DPC DPC DPC FIFO Queue DPC DPC FIFO Queue 4 Task level drops and DPC can execute 5 Transfer control to driver’s DPC user-level threads Interrupts DPC

11. 1/9/2016 08:46 11 Servicing an interrupt Power Failure...... APC Normal Exec. Dispatch/DPC Device X...... Interrupt Dispatch Table 1 Device interrupts 2 Transfer control to ISR Interrupt Service Routine DPC Routine Device Driver 3 Stop int.. and queue DPC DPC DPC FIFO Queue DPC DPC FIFO Queue 4 Task level drops and DPC can execute 5 Transfer control to driver’s DPC 6 Execution of DPC routine user-level threads Interrupts DPC

12. 1/9/2016 08:46 12 I/O Handling  I/O request is sent to device driver.  Device completes operation and interrupts.  Complete I/O request. Buffered I/ODirect I/O APC Device System User’s space Device System User’s space (Keyboard, mouse) (disk, network)