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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 
33 extern int delayacct_on; /* Delay accounting turned on/off */
34 extern struct kmem_cache *delayacct_cache;
35 extern void delayacct_init(void);
36 extern void __delayacct_tsk_init(struct task_struct *);
37 extern void __delayacct_tsk_exit(struct task_struct *);
38 extern void __delayacct_blkio_start(void);
39 extern void __delayacct_blkio_end(void);
40 extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
42 extern void __delayacct_freepages_start(void);
43 extern void __delayacct_freepages_end(void);
44 
45 static 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 
53 static inline void delayacct_set_flag(int flag)
54 {
55  if (current->delays)
56  current->delays->flags |= flag;
57 }
58 
59 static inline void delayacct_clear_flag(int flag)
60 {
61  if (current->delays)
62  current->delays->flags &= ~flag;
63 }
64 
65 static 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)
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  */
76 static 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 
83 static inline void delayacct_blkio_start(void)
84 {
85  delayacct_set_flag(DELAYACCT_PF_BLKIO);
86  if (current->delays)
88 }
89 
90 static inline void delayacct_blkio_end(void)
91 {
92  if (current->delays)
94  delayacct_clear_flag(DELAYACCT_PF_BLKIO);
95 }
96 
97 static 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 
105 static 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 
112 static inline void delayacct_freepages_start(void)
113 {
114  if (current->delays)
116 }
117 
118 static inline void delayacct_freepages_end(void)
119 {
120  if (current->delays)
122 }
123 
124 #else
125 static inline void delayacct_set_flag(int flag)
126 {}
127 static inline void delayacct_clear_flag(int flag)
128 {}
129 static inline void delayacct_init(void)
130 {}
131 static inline void delayacct_tsk_init(struct task_struct *tsk)
132 {}
133 static inline void delayacct_tsk_free(struct task_struct *tsk)
134 {}
135 static inline void delayacct_blkio_start(void)
136 {}
137 static inline void delayacct_blkio_end(void)
138 {}
139 static inline int delayacct_add_tsk(struct taskstats *d,
140  struct task_struct *tsk)
141 { return 0; }
142 static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
143 { return 0; }
144 static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
145 { return 0; }
146 static inline void delayacct_freepages_start(void)
147 {}
148 static inline void delayacct_freepages_end(void)
149 {}
150 
151 #endif /* CONFIG_TASK_DELAY_ACCT */
152 
153 #endif