delayacct: track delays from thrashing cache pages
[muen/linux.git] / include / linux / delayacct.h
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 <uapi/linux/taskstats.h>
21
22 /*
23  * Per-task flags relevant to delay accounting
24  * maintained privately to avoid exhausting similar flags in sched.h:PF_*
25  * Used to set current->delays->flags
26  */
27 #define DELAYACCT_PF_SWAPIN     0x00000001      /* I am doing a swapin */
28 #define DELAYACCT_PF_BLKIO      0x00000002      /* I am waiting on IO */
29
30 #ifdef CONFIG_TASK_DELAY_ACCT
31 struct task_delay_info {
32         raw_spinlock_t  lock;
33         unsigned int    flags;  /* Private per-task flags */
34
35         /* For each stat XXX, add following, aligned appropriately
36          *
37          * struct timespec XXX_start, XXX_end;
38          * u64 XXX_delay;
39          * u32 XXX_count;
40          *
41          * Atomicity of updates to XXX_delay, XXX_count protected by
42          * single lock above (split into XXX_lock if contention is an issue).
43          */
44
45         /*
46          * XXX_count is incremented on every XXX operation, the delay
47          * associated with the operation is added to XXX_delay.
48          * XXX_delay contains the accumulated delay time in nanoseconds.
49          */
50         u64 blkio_start;        /* Shared by blkio, swapin */
51         u64 blkio_delay;        /* wait for sync block io completion */
52         u64 swapin_delay;       /* wait for swapin block io completion */
53         u32 blkio_count;        /* total count of the number of sync block */
54                                 /* io operations performed */
55         u32 swapin_count;       /* total count of the number of swapin block */
56                                 /* io operations performed */
57
58         u64 freepages_start;
59         u64 freepages_delay;    /* wait for memory reclaim */
60
61         u64 thrashing_start;
62         u64 thrashing_delay;    /* wait for thrashing page */
63
64         u32 freepages_count;    /* total count of memory reclaim */
65         u32 thrashing_count;    /* total count of thrash waits */
66 };
67 #endif
68
69 #include <linux/sched.h>
70 #include <linux/slab.h>
71
72 #ifdef CONFIG_TASK_DELAY_ACCT
73 extern int delayacct_on;        /* Delay accounting turned on/off */
74 extern struct kmem_cache *delayacct_cache;
75 extern void delayacct_init(void);
76 extern void __delayacct_tsk_init(struct task_struct *);
77 extern void __delayacct_tsk_exit(struct task_struct *);
78 extern void __delayacct_blkio_start(void);
79 extern void __delayacct_blkio_end(struct task_struct *);
80 extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
81 extern __u64 __delayacct_blkio_ticks(struct task_struct *);
82 extern void __delayacct_freepages_start(void);
83 extern void __delayacct_freepages_end(void);
84 extern void __delayacct_thrashing_start(void);
85 extern void __delayacct_thrashing_end(void);
86
87 static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
88 {
89         if (p->delays)
90                 return (p->delays->flags & DELAYACCT_PF_BLKIO);
91         else
92                 return 0;
93 }
94
95 static inline void delayacct_set_flag(int flag)
96 {
97         if (current->delays)
98                 current->delays->flags |= flag;
99 }
100
101 static inline void delayacct_clear_flag(int flag)
102 {
103         if (current->delays)
104                 current->delays->flags &= ~flag;
105 }
106
107 static inline void delayacct_tsk_init(struct task_struct *tsk)
108 {
109         /* reinitialize in case parent's non-null pointer was dup'ed*/
110         tsk->delays = NULL;
111         if (delayacct_on)
112                 __delayacct_tsk_init(tsk);
113 }
114
115 /* Free tsk->delays. Called from bad fork and __put_task_struct
116  * where there's no risk of tsk->delays being accessed elsewhere
117  */
118 static inline void delayacct_tsk_free(struct task_struct *tsk)
119 {
120         if (tsk->delays)
121                 kmem_cache_free(delayacct_cache, tsk->delays);
122         tsk->delays = NULL;
123 }
124
125 static inline void delayacct_blkio_start(void)
126 {
127         delayacct_set_flag(DELAYACCT_PF_BLKIO);
128         if (current->delays)
129                 __delayacct_blkio_start();
130 }
131
132 static inline void delayacct_blkio_end(struct task_struct *p)
133 {
134         if (p->delays)
135                 __delayacct_blkio_end(p);
136         delayacct_clear_flag(DELAYACCT_PF_BLKIO);
137 }
138
139 static inline int delayacct_add_tsk(struct taskstats *d,
140                                         struct task_struct *tsk)
141 {
142         if (!delayacct_on || !tsk->delays)
143                 return 0;
144         return __delayacct_add_tsk(d, tsk);
145 }
146
147 static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
148 {
149         if (tsk->delays)
150                 return __delayacct_blkio_ticks(tsk);
151         return 0;
152 }
153
154 static inline void delayacct_freepages_start(void)
155 {
156         if (current->delays)
157                 __delayacct_freepages_start();
158 }
159
160 static inline void delayacct_freepages_end(void)
161 {
162         if (current->delays)
163                 __delayacct_freepages_end();
164 }
165
166 static inline void delayacct_thrashing_start(void)
167 {
168         if (current->delays)
169                 __delayacct_thrashing_start();
170 }
171
172 static inline void delayacct_thrashing_end(void)
173 {
174         if (current->delays)
175                 __delayacct_thrashing_end();
176 }
177
178 #else
179 static inline void delayacct_set_flag(int flag)
180 {}
181 static inline void delayacct_clear_flag(int flag)
182 {}
183 static inline void delayacct_init(void)
184 {}
185 static inline void delayacct_tsk_init(struct task_struct *tsk)
186 {}
187 static inline void delayacct_tsk_free(struct task_struct *tsk)
188 {}
189 static inline void delayacct_blkio_start(void)
190 {}
191 static inline void delayacct_blkio_end(struct task_struct *p)
192 {}
193 static inline int delayacct_add_tsk(struct taskstats *d,
194                                         struct task_struct *tsk)
195 { return 0; }
196 static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
197 { return 0; }
198 static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
199 { return 0; }
200 static inline void delayacct_freepages_start(void)
201 {}
202 static inline void delayacct_freepages_end(void)
203 {}
204 static inline void delayacct_thrashing_start(void)
205 {}
206 static inline void delayacct_thrashing_end(void)
207 {}
208
209 #endif /* CONFIG_TASK_DELAY_ACCT */
210
211 #endif