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_CLASS_SHIFT (13) 11 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) 12 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) 16 17 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) 18 19 /* 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. 24 */ 25 enum { 26 IOPRIO_CLASS_NONE, 27 IOPRIO_CLASS_RT, 28 IOPRIO_CLASS_BE, 29 IOPRIO_CLASS_IDLE, 30 }; 31 32 /* 33 * 8 best effort priority levels are supported 34 */ 35 #define IOPRIO_BE_NR (8) 36 37 enum { 38 IOPRIO_WHO_PROCESS = 1, 39 IOPRIO_WHO_PGRP, 40 IOPRIO_WHO_USER, 41 }; 42 43 /* 44 * Fallback BE priority 45 */ 46 #define IOPRIO_NORM (4) 47 48 /* 49 * if process has set io priority explicitly, use that. if not, convert 50 * the cpu scheduler nice value to an io priority 51 */ 52 static inline int task_nice_ioprio(struct task_struct *task) 53 { 54 return (task_nice(task) + 20) / 5; 55 } 56 57 /* 58 * This is for the case where the task hasn't asked for a specific IO class. 59 * Check for idle and rt task process, and return appropriate IO class. 60 */ 61 static inline int task_nice_ioclass(struct task_struct *task) 62 { 63 if (task->policy == SCHED_IDLE) 64 return IOPRIO_CLASS_IDLE; 65 else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR) 66 return IOPRIO_CLASS_RT; 67 else 68 return IOPRIO_CLASS_BE; 69 } 70 71 /* 72 * For inheritance, return the highest of the two given priorities 73 */ 74 extern int ioprio_best(unsigned short aprio, unsigned short bprio); 75 76 extern int set_task_ioprio(struct task_struct *task, int ioprio); 77 78 #endif 79