LCOV - code coverage report
Current view: top level - include/linux - ioprio.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 1 1 100.0 %
Date: 2017-01-25 Functions: 0 0 -

          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             :  * if process has set io priority explicitly, use that. if not, convert
      46             :  * the cpu scheduler nice value to an io priority
      47             :  */
      48             : #define IOPRIO_NORM     (4)
      49             : static inline int task_ioprio(struct io_context *ioc)
      50             : {
      51             :         if (ioprio_valid(ioc->ioprio))
      52             :                 return IOPRIO_PRIO_DATA(ioc->ioprio);
      53             : 
      54             :         return IOPRIO_NORM;
      55             : }
      56             : 
      57             : static inline int task_ioprio_class(struct io_context *ioc)
      58             : {
      59             :         if (ioprio_valid(ioc->ioprio))
      60             :                 return IOPRIO_PRIO_CLASS(ioc->ioprio);
      61             : 
      62             :         return IOPRIO_CLASS_BE;
      63             : }
      64             : 
      65             : static inline int task_nice_ioprio(struct task_struct *task)
      66             : {
      67             :         return (task_nice(task) + 20) / 5;
      68             : }
      69             : 
      70             : /*
      71             :  * This is for the case where the task hasn't asked for a specific IO class.
      72             :  * Check for idle and rt task process, and return appropriate IO class.
      73             :  */
      74             : static inline int task_nice_ioclass(struct task_struct *task)
      75             : {
      76             :         if (task->policy == SCHED_IDLE)
      77             :                 return IOPRIO_CLASS_IDLE;
      78             :         else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)
      79             :                 return IOPRIO_CLASS_RT;
      80             :         else
      81             :                 return IOPRIO_CLASS_BE;
      82             : }
      83             : 
      84             : /*
      85             :  * For inheritance, return the highest of the two given priorities
      86             :  */
      87             : extern int ioprio_best(unsigned short aprio, unsigned short bprio);
      88             : 
      89             : extern int set_task_ioprio(struct task_struct *task, int ioprio);
      90           1 : 
      91             : #endif

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