1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef IOPRIO_H 3 #define IOPRIO_H 4 5 #include <linux/sched.h> 6 #include <linux/sched/rt.h> 7 #include <linux/iocontext.h> 8 9 /* 10 * Gives us 8 prio classes with 13-bits of data for each class 11 */ 12 #define IOPRIO_CLASS_SHIFT (13) 13 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) 14 15 #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT) 16 #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK) 17 #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) 18 19 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) 20 21 /* 22 * These are the io priority groups as implemented by CFQ. RT is the realtime 23 * class, it always gets premium service. BE is the best-effort scheduling 24 * class, the default for any process. IDLE is the idle scheduling class, it 25 * is only served when no one else is using the disk. 26 */ 27 enum { 28 IOPRIO_CLASS_NONE, 29 IOPRIO_CLASS_RT, 30 IOPRIO_CLASS_BE, 31 IOPRIO_CLASS_IDLE, 32 }; 33 34 /* 35 * 8 best effort priority levels are supported 36 */ 37 #define IOPRIO_BE_NR (8) 38 39 enum { 40 IOPRIO_WHO_PROCESS = 1, 41 IOPRIO_WHO_PGRP, 42 IOPRIO_WHO_USER, 43 }; 44 45 /* 46 * Fallback BE priority 47 */ 48 #define IOPRIO_NORM (4) 49 50 /* 51 * if process has set io priority explicitly, use that. if not, convert 52 * the cpu scheduler nice value to an io priority 53 */ 54 static inline int task_nice_ioprio(struct task_struct *task) 55 { 56 return (task_nice(task) + 20) / 5; 57 } 58 59 /* 60 * This is for the case where the task hasn't asked for a specific IO class. 61 * Check for idle and rt task process, and return appropriate IO class. 62 */ 63 static inline int task_nice_ioclass(struct task_struct *task) 64 { 65 if (task->policy == SCHED_IDLE) 66 return IOPRIO_CLASS_IDLE; 67 else if (task_is_realtime(task)) 68 return IOPRIO_CLASS_RT; 69 else 70 return IOPRIO_CLASS_BE; 71 } 72 73 /* 74 * For inheritance, return the highest of the two given priorities 75 */ 76 extern int ioprio_best(unsigned short aprio, unsigned short bprio); 77 78 extern int set_task_ioprio(struct task_struct *task, int ioprio); 79 80 #ifdef CONFIG_BLOCK 81 extern int ioprio_check_cap(int ioprio); 82 #else 83 static inline int ioprio_check_cap(int ioprio) 84 { 85 return -ENOTBLK; 86 } 87 #endif /* CONFIG_BLOCK */ 88 89 #endif 90