4 #include <linux/sched.h>
7 * Gives us 8 prio classes with 13-bits of data for each class
9 #define IOPRIO_BITS (16)
10 #define IOPRIO_CLASS_SHIFT (13)
11 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
13 #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
14 #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
16 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
19 * These are the io priority groups as implemented by CFQ. RT is the realtime
20 * class, it always gets premium service. BE is the best-effort scheduling
21 * class, the default for any process. IDLE is the idle scheduling class, it
22 * is only served when no one else is using the disk.
32 * 8 best effort priority levels are supported
34 #define IOPRIO_BE_NR (8)
36 asmlinkage int sys_ioprio_set(int, int, int);
37 asmlinkage int sys_ioprio_get(int, int);
40 IOPRIO_WHO_PROCESS = 1,
46 * if process has set io priority explicitly, use that. if not, convert
47 * the cpu scheduler nice value to an io priority
49 #define IOPRIO_NORM (4)
50 static inline int task_ioprio(struct task_struct *task)
52 WARN_ON(!ioprio_valid(task->ioprio));
53 return IOPRIO_PRIO_DATA(task->ioprio);
56 static inline int task_nice_ioprio(struct task_struct *task)
58 return (task_nice(task) + 20) / 5;
62 * For inheritance, return the highest of the two given priorities
64 static inline int ioprio_best(unsigned short aprio, unsigned short bprio)
66 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
67 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
69 if (!ioprio_valid(aprio))
71 if (!ioprio_valid(bprio))
74 if (aclass == IOPRIO_CLASS_NONE)
75 aclass = IOPRIO_CLASS_BE;
76 if (bclass == IOPRIO_CLASS_NONE)
77 bclass = IOPRIO_CLASS_BE;
80 return min(aprio, bprio);