linux/include/linux/delayacct.h
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   1/* delayacct.h - per-task delay accounting
   2 *
   3 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
   4 *
   5 * This program is free software;  you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY;  without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  13 * the GNU General Public License for more details.
  14 *
  15 */
  16
  17#ifndef _LINUX_DELAYACCT_H
  18#define _LINUX_DELAYACCT_H
  19
  20#include <linux/sched.h>
  21#include <linux/slab.h>
  22
  23/*
  24 * Per-task flags relevant to delay accounting
  25 * maintained privately to avoid exhausting similar flags in sched.h:PF_*
  26 * Used to set current->delays->flags
  27 */
  28#define DELAYACCT_PF_SWAPIN     0x00000001      /* I am doing a swapin */
  29#define DELAYACCT_PF_BLKIO      0x00000002      /* I am waiting on IO */
  30
  31#ifdef CONFIG_TASK_DELAY_ACCT
  32
  33extern int delayacct_on;        /* Delay accounting turned on/off */
  34extern struct kmem_cache *delayacct_cache;
  35extern void delayacct_init(void);
  36extern void __delayacct_tsk_init(struct task_struct *);
  37extern void __delayacct_tsk_exit(struct task_struct *);
  38extern void __delayacct_blkio_start(void);
  39extern void __delayacct_blkio_end(void);
  40extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
  41extern __u64 __delayacct_blkio_ticks(struct task_struct *);
  42extern void __delayacct_freepages_start(void);
  43extern void __delayacct_freepages_end(void);
  44
  45static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
  46{
  47        if (p->delays)
  48                return (p->delays->flags & DELAYACCT_PF_BLKIO);
  49        else
  50                return 0;
  51}
  52
  53static inline void delayacct_set_flag(int flag)
  54{
  55        if (current->delays)
  56                current->delays->flags |= flag;
  57}
  58
  59static inline void delayacct_clear_flag(int flag)
  60{
  61        if (current->delays)
  62                current->delays->flags &= ~flag;
  63}
  64
  65static inline void delayacct_tsk_init(struct task_struct *tsk)
  66{
  67        /* reinitialize in case parent's non-null pointer was dup'ed*/
  68        tsk->delays = NULL;
  69        if (delayacct_on)
  70                __delayacct_tsk_init(tsk);
  71}
  72
  73/* Free tsk->delays. Called from bad fork and __put_task_struct
  74 * where there's no risk of tsk->delays being accessed elsewhere
  75 */
  76static inline void delayacct_tsk_free(struct task_struct *tsk)
  77{
  78        if (tsk->delays)
  79                kmem_cache_free(delayacct_cache, tsk->delays);
  80        tsk->delays = NULL;
  81}
  82
  83static inline void delayacct_blkio_start(void)
  84{
  85        delayacct_set_flag(DELAYACCT_PF_BLKIO);
  86        if (current->delays)
  87                __delayacct_blkio_start();
  88}
  89
  90static inline void delayacct_blkio_end(void)
  91{
  92        if (current->delays)
  93                __delayacct_blkio_end();
  94        delayacct_clear_flag(DELAYACCT_PF_BLKIO);
  95}
  96
  97static inline int delayacct_add_tsk(struct taskstats *d,
  98                                        struct task_struct *tsk)
  99{
 100        if (!delayacct_on || !tsk->delays)
 101                return 0;
 102        return __delayacct_add_tsk(d, tsk);
 103}
 104
 105static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
 106{
 107        if (tsk->delays)
 108                return __delayacct_blkio_ticks(tsk);
 109        return 0;
 110}
 111
 112static inline void delayacct_freepages_start(void)
 113{
 114        if (current->delays)
 115                __delayacct_freepages_start();
 116}
 117
 118static inline void delayacct_freepages_end(void)
 119{
 120        if (current->delays)
 121                __delayacct_freepages_end();
 122}
 123
 124#else
 125static inline void delayacct_set_flag(int flag)
 126{}
 127static inline void delayacct_clear_flag(int flag)
 128{}
 129static inline void delayacct_init(void)
 130{}
 131static inline void delayacct_tsk_init(struct task_struct *tsk)
 132{}
 133static inline void delayacct_tsk_free(struct task_struct *tsk)
 134{}
 135static inline void delayacct_blkio_start(void)
 136{}
 137static inline void delayacct_blkio_end(void)
 138{}
 139static inline int delayacct_add_tsk(struct taskstats *d,
 140                                        struct task_struct *tsk)
 141{ return 0; }
 142static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
 143{ return 0; }
 144static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
 145{ return 0; }
 146static inline void delayacct_freepages_start(void)
 147{}
 148static inline void delayacct_freepages_end(void)
 149{}
 150
 151#endif /* CONFIG_TASK_DELAY_ACCT */
 152
 153#endif
 154
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