#ifndef IOPRIO_H #define IOPRIO_H #include <linux/sched.h> /* * Gives us 8 prio classes with 13-bits of data for each class */ #define IOPRIO_BITS (16) #define IOPRIO_CLASS_SHIFT (13) #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT) #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK) #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) /* * These are the io priority groups as implemented by CFQ. RT is the realtime * class, it always gets premium service. BE is the best-effort scheduling * class, the default for any process. IDLE is the idle scheduling class, it * is only served when no one else is using the disk. */ enum { IOPRIO_CLASS_NONE, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE, }; /* * 8 best effort priority levels are supported */ #define IOPRIO_BE_NR (8) enum { IOPRIO_WHO_PROCESS = 1, IOPRIO_WHO_PGRP, IOPRIO_WHO_USER, }; /* * if process has set io priority explicitly, use that. if not, convert * the cpu scheduler nice value to an io priority */ #define IOPRIO_NORM (4) static inline int task_ioprio(struct task_struct *task) { WARN_ON(!ioprio_valid(task->ioprio)); return IOPRIO_PRIO_DATA(task->ioprio); } static inline int task_nice_ioprio(struct task_struct *task) { return (task_nice(task) + 20) / 5; } /* * For inheritance, return the highest of the two given priorities */ static inline int ioprio_best(unsigned short aprio, unsigned short bprio) { unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); if (!ioprio_valid(aprio)) return bprio; if (!ioprio_valid(bprio)) return aprio; if (aclass == IOPRIO_CLASS_NONE) aclass = IOPRIO_CLASS_BE; if (bclass == IOPRIO_CLASS_NONE) bclass = IOPRIO_CLASS_BE; if (aclass == bclass) return min(aprio, bprio); if (aclass > bclass) return bprio; else return aprio; } #endif