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)
15 #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
17 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
20 * These are the io priority groups as implemented by CFQ. RT is the realtime
21 * class, it always gets premium service. BE is the best-effort scheduling
22 * class, the default for any process. IDLE is the idle scheduling class, it
23 * is only served when no one else is using the disk.
33 * 8 best effort priority levels are supported
35 #define IOPRIO_BE_NR (8)
37 asmlinkage int sys_ioprio_set(int, int, int);
38 asmlinkage int sys_ioprio_get(int, int);
41 IOPRIO_WHO_PROCESS = 1,
47 * if process has set io priority explicitly, use that. if not, convert
48 * the cpu scheduler nice value to an io priority
50 #define IOPRIO_NORM (4)
51 static inline int task_ioprio(struct task_struct *task)
53 WARN_ON(!ioprio_valid(task->ioprio));
54 return IOPRIO_PRIO_DATA(task->ioprio);
57 static inline int task_nice_ioprio(struct task_struct *task)
59 return (task_nice(task) + 20) / 5;
63 * For inheritance, return the highest of the two given priorities
65 static inline int ioprio_best(unsigned short aprio, unsigned short bprio)
67 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
68 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
70 if (!ioprio_valid(aprio))
72 if (!ioprio_valid(bprio))
75 if (aclass == IOPRIO_CLASS_NONE)
76 aclass = IOPRIO_CLASS_BE;
77 if (bclass == IOPRIO_CLASS_NONE)
78 bclass = IOPRIO_CLASS_BE;
81 return min(aprio, bprio);