4 #include <linux/sched.h>
5 #include <linux/iocontext.h>
8 * Gives us 8 prio classes with 13-bits of data for each class
10 #define IOPRIO_BITS (16)
11 #define IOPRIO_CLASS_SHIFT (13)
12 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
14 #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
15 #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
16 #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
18 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
21 * These are the io priority groups as implemented by CFQ. RT is the realtime
22 * class, it always gets premium service. BE is the best-effort scheduling
23 * class, the default for any process. IDLE is the idle scheduling class, it
24 * is only served when no one else is using the disk.
34 * 8 best effort priority levels are supported
36 #define IOPRIO_BE_NR (8)
39 IOPRIO_WHO_PROCESS
= 1,
45 * if process has set io priority explicitly, use that. if not, convert
46 * the cpu scheduler nice value to an io priority
48 #define IOPRIO_NORM (4)
49 static inline int task_ioprio(struct io_context
*ioc
)
51 if (ioprio_valid(ioc
->ioprio
))
52 return IOPRIO_PRIO_DATA(ioc
->ioprio
);
57 static inline int task_ioprio_class(struct io_context
*ioc
)
59 if (ioprio_valid(ioc
->ioprio
))
60 return IOPRIO_PRIO_CLASS(ioc
->ioprio
);
62 return IOPRIO_CLASS_BE
;
65 static inline int task_nice_ioprio(struct task_struct
*task
)
67 return (task_nice(task
) + 20) / 5;
71 * This is for the case where the task hasn't asked for a specific IO class.
72 * Check for idle and rt task process, and return appropriate IO class.
74 static inline int task_nice_ioclass(struct task_struct
*task
)
76 if (task
->policy
== SCHED_IDLE
)
77 return IOPRIO_CLASS_IDLE
;
78 else if (task
->policy
== SCHED_FIFO
|| task
->policy
== SCHED_RR
)
79 return IOPRIO_CLASS_RT
;
81 return IOPRIO_CLASS_BE
;
85 * For inheritance, return the highest of the two given priorities
87 extern int ioprio_best(unsigned short aprio
, unsigned short bprio
);
89 extern int set_task_ioprio(struct task_struct
*task
, int ioprio
);
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