Branch data     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                 :       2706 :         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         [ +  - ]:     829848 :         if (task->policy == SCHED_IDLE)
      65                 :            :                 return IOPRIO_CLASS_IDLE;
      66         [ +  - ]:       2706 :         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