Line data    Source code

       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         372 :         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         372 :         if (task->policy == SCHED_IDLE)
      65             :                 return IOPRIO_CLASS_IDLE;
      66         372 :         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