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1====================
2The struct taskstats
3====================
4
5This document contains an explanation of the struct taskstats fields.
6
7There are three different groups of fields in the struct taskstats:
8
91) Common and basic accounting fields
10 If CONFIG_TASKSTATS is set, the taskstats interface is enabled and
11 the common fields and basic accounting fields are collected for
12 delivery at do_exit() of a task.
132) Delay accounting fields
14 These fields are placed between::
15
16 /* Delay accounting fields start */
17
18 and::
19
20 /* Delay accounting fields end */
21
22 Their values are collected if CONFIG_TASK_DELAY_ACCT is set.
233) Extended accounting fields
24 These fields are placed between::
25
26 /* Extended accounting fields start */
27
28 and::
29
30 /* Extended accounting fields end */
31
32 Their values are collected if CONFIG_TASK_XACCT is set.
33
344) Per-task and per-thread context switch count statistics
35
365) Time accounting for SMT machines
37
386) Extended delay accounting fields for memory reclaim
39
40Future extension should add fields to the end of the taskstats struct, and
41should not change the relative position of each field within the struct.
42
43::
44
45 struct taskstats {
46
471) Common and basic accounting fields::
48
49 /* The version number of this struct. This field is always set to
50 * TASKSTATS_VERSION, which is defined in <linux/taskstats.h>.
51 * Each time the struct is changed, the value should be incremented.
52 */
53 __u16 version;
54
55 /* The exit code of a task. */
56 __u32 ac_exitcode; /* Exit status */
57
58 /* The accounting flags of a task as defined in <linux/acct.h>
59 * Defined values are AFORK, ASU, ACOMPAT, ACORE, and AXSIG.
60 */
61 __u8 ac_flag; /* Record flags */
62
63 /* The value of task_nice() of a task. */
64 __u8 ac_nice; /* task_nice */
65
66 /* The name of the command that started this task. */
67 char ac_comm[TS_COMM_LEN]; /* Command name */
68
69 /* The scheduling discipline as set in task->policy field. */
70 __u8 ac_sched; /* Scheduling discipline */
71
72 __u8 ac_pad[3];
73 __u32 ac_uid; /* User ID */
74 __u32 ac_gid; /* Group ID */
75 __u32 ac_pid; /* Process ID */
76 __u32 ac_ppid; /* Parent process ID */
77
78 /* The time when a task begins, in [secs] since 1970. */
79 __u32 ac_btime; /* Begin time [sec since 1970] */
80
81 /* The elapsed time of a task, in [usec]. */
82 __u64 ac_etime; /* Elapsed time [usec] */
83
84 /* The user CPU time of a task, in [usec]. */
85 __u64 ac_utime; /* User CPU time [usec] */
86
87 /* The system CPU time of a task, in [usec]. */
88 __u64 ac_stime; /* System CPU time [usec] */
89
90 /* The minor page fault count of a task, as set in task->min_flt. */
91 __u64 ac_minflt; /* Minor Page Fault Count */
92
93 /* The major page fault count of a task, as set in task->maj_flt. */
94 __u64 ac_majflt; /* Major Page Fault Count */
95
96
972) Delay accounting fields::
98
99 /* Delay accounting fields start
100 *
101 * All values, until the comment "Delay accounting fields end" are
102 * available only if delay accounting is enabled, even though the last
103 * few fields are not delays
104 *
105 * xxx_count is the number of delay values recorded
106 * xxx_delay_total is the corresponding cumulative delay in nanoseconds
107 *
108 * xxx_delay_total wraps around to zero on overflow
109 * xxx_count incremented regardless of overflow
110 */
111
112 /* Delay waiting for cpu, while runnable
113 * count, delay_total NOT updated atomically
114 */
115 __u64 cpu_count;
116 __u64 cpu_delay_total;
117
118 /* Following four fields atomically updated using task->delays->lock */
119
120 /* Delay waiting for synchronous block I/O to complete
121 * does not account for delays in I/O submission
122 */
123 __u64 blkio_count;
124 __u64 blkio_delay_total;
125
126 /* Delay waiting for page fault I/O (swap in only) */
127 __u64 swapin_count;
128 __u64 swapin_delay_total;
129
130 /* cpu "wall-clock" running time
131 * On some architectures, value will adjust for cpu time stolen
132 * from the kernel in involuntary waits due to virtualization.
133 * Value is cumulative, in nanoseconds, without a corresponding count
134 * and wraps around to zero silently on overflow
135 */
136 __u64 cpu_run_real_total;
137
138 /* cpu "virtual" running time
139 * Uses time intervals seen by the kernel i.e. no adjustment
140 * for kernel's involuntary waits due to virtualization.
141 * Value is cumulative, in nanoseconds, without a corresponding count
142 * and wraps around to zero silently on overflow
143 */
144 __u64 cpu_run_virtual_total;
145 /* Delay accounting fields end */
146 /* version 1 ends here */
147
148
1493) Extended accounting fields::
150
151 /* Extended accounting fields start */
152
153 /* Accumulated RSS usage in duration of a task, in MBytes-usecs.
154 * The current rss usage is added to this counter every time
155 * a tick is charged to a task's system time. So, at the end we
156 * will have memory usage multiplied by system time. Thus an
157 * average usage per system time unit can be calculated.
158 */
159 __u64 coremem; /* accumulated RSS usage in MB-usec */
160
161 /* Accumulated virtual memory usage in duration of a task.
162 * Same as acct_rss_mem1 above except that we keep track of VM usage.
163 */
164 __u64 virtmem; /* accumulated VM usage in MB-usec */
165
166 /* High watermark of RSS usage in duration of a task, in KBytes. */
167 __u64 hiwater_rss; /* High-watermark of RSS usage */
168
169 /* High watermark of VM usage in duration of a task, in KBytes. */
170 __u64 hiwater_vm; /* High-water virtual memory usage */
171
172 /* The following four fields are I/O statistics of a task. */
173 __u64 read_char; /* bytes read */
174 __u64 write_char; /* bytes written */
175 __u64 read_syscalls; /* read syscalls */
176 __u64 write_syscalls; /* write syscalls */
177
178 /* Extended accounting fields end */
179
1804) Per-task and per-thread statistics::
181
182 __u64 nvcsw; /* Context voluntary switch counter */
183 __u64 nivcsw; /* Context involuntary switch counter */
184
1855) Time accounting for SMT machines::
186
187 __u64 ac_utimescaled; /* utime scaled on frequency etc */
188 __u64 ac_stimescaled; /* stime scaled on frequency etc */
189 __u64 cpu_scaled_run_real_total; /* scaled cpu_run_real_total */
190
1916) Extended delay accounting fields for memory reclaim::
192
193 /* Delay waiting for memory reclaim */
194 __u64 freepages_count;
195 __u64 freepages_delay_total;
196
197::
198
199 }