1 #ifndef IOPRIO_H 2 #define IOPRIO_H 3 4 #include <linux/sched.h> 5 #include <linux/iocontext.h> 6 7 /* 8 * Gives us 8 prio classes with 13-bits of data for each class 9 */ 10 #define IOPRIO_BITS (16) 11 #define IOPRIO_CLASS_SHIFT (13) 12 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) 13 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) 17 18 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) 19 20 /* 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. 25 */ 26 enum { 27 IOPRIO_CLASS_NONE, 28 IOPRIO_CLASS_RT, 29 IOPRIO_CLASS_BE, 30 IOPRIO_CLASS_IDLE, 31 }; 32 33 /* 34 * 8 best effort priority levels are supported 35 */ 36 #define IOPRIO_BE_NR (8) 37 38 enum { 39 IOPRIO_WHO_PROCESS = 1, 40 IOPRIO_WHO_PGRP, 41 IOPRIO_WHO_USER, 42 }; 43 44 /* 45 * Fallback BE priority 46 */ 47 #define IOPRIO_NORM (4) 48 49 /* 50 * if process has set io priority explicitly, use that. if not, convert 51 * the cpu scheduler nice value to an io priority 52 */ 53 static inline int task_nice_ioprio(struct task_struct *task) 54 { 55 return (task_nice(task) + 20) / 5; 56 } 57 58 /* 59 * This is for the case where the task hasn't asked for a specific IO class. 60 * Check for idle and rt task process, and return appropriate IO class. 61 */ 62 static inline int task_nice_ioclass(struct task_struct *task) 63 { 64 if (task->policy == SCHED_IDLE) 65 return IOPRIO_CLASS_IDLE; 66 else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR) 67 return IOPRIO_CLASS_RT; 68 else 69 return IOPRIO_CLASS_BE; 70 } 71 72 /* 73 * For inheritance, return the highest of the two given priorities 74 */ 75 extern int ioprio_best(unsigned short aprio, unsigned short bprio); 76 77 extern int set_task_ioprio(struct task_struct *task, int ioprio); 78 79 #endif 80