1The struct taskstats
2--------------------
3
4This document contains an explanation of the struct taskstats fields.
5
6There are three different groups of fields in the struct taskstats:
7
81) Common and basic accounting fields
9    If CONFIG_TASKSTATS is set, the taskstats inteface is enabled and
10    the common fields and basic accounting fields are collected for
11    delivery at do_exit() of a task.
122) Delay accounting fields
13    These fields are placed between
14    /* Delay accounting fields start */
15    and
16    /* Delay accounting fields end */
17    Their values are collected if CONFIG_TASK_DELAY_ACCT is set.
183) Extended accounting fields
19    These fields are placed between
20    /* Extended accounting fields start */
21    and
22    /* Extended accounting fields end */
23    Their values are collected if CONFIG_TASK_XACCT is set.
24
25Future extension should add fields to the end of the taskstats struct, and
26should not change the relative position of each field within the struct.
27
28
29struct taskstats {
30
311) Common and basic accounting fields:
32	/* The version number of this struct. This field is always set to
33	 * TAKSTATS_VERSION, which is defined in <linux/taskstats.h>.
34	 * Each time the struct is changed, the value should be incremented.
35	 */
36	__u16	version;
37
38  	/* The exit code of a task. */
39	__u32	ac_exitcode;		/* Exit status */
40
41  	/* The accounting flags of a task as defined in <linux/acct.h>
42	 * Defined values are AFORK, ASU, ACOMPAT, ACORE, and AXSIG.
43	 */
44	__u8	ac_flag;		/* Record flags */
45
46  	/* The value of task_nice() of a task. */
47	__u8	ac_nice;		/* task_nice */
48
49  	/* The name of the command that started this task. */
50	char	ac_comm[TS_COMM_LEN];	/* Command name */
51
52  	/* The scheduling discipline as set in task->policy field. */
53	__u8	ac_sched;		/* Scheduling discipline */
54
55	__u8	ac_pad[3];
56	__u32	ac_uid;			/* User ID */
57	__u32	ac_gid;			/* Group ID */
58	__u32	ac_pid;			/* Process ID */
59	__u32	ac_ppid;		/* Parent process ID */
60
61  	/* The time when a task begins, in [secs] since 1970. */
62	__u32	ac_btime;		/* Begin time [sec since 1970] */
63
64  	/* The elapsed time of a task, in [usec]. */
65	__u64	ac_etime;		/* Elapsed time [usec] */
66
67  	/* The user CPU time of a task, in [usec]. */
68	__u64	ac_utime;		/* User CPU time [usec] */
69
70  	/* The system CPU time of a task, in [usec]. */
71	__u64	ac_stime;		/* System CPU time [usec] */
72
73  	/* The minor page fault count of a task, as set in task->min_flt. */
74	__u64	ac_minflt;		/* Minor Page Fault Count */
75
76	/* The major page fault count of a task, as set in task->maj_flt. */
77	__u64	ac_majflt;		/* Major Page Fault Count */
78
79
802) Delay accounting fields:
81	/* Delay accounting fields start
82	 *
83	 * All values, until the comment "Delay accounting fields end" are
84	 * available only if delay accounting is enabled, even though the last
85	 * few fields are not delays
86	 *
87	 * xxx_count is the number of delay values recorded
88	 * xxx_delay_total is the corresponding cumulative delay in nanoseconds
89	 *
90	 * xxx_delay_total wraps around to zero on overflow
91	 * xxx_count incremented regardless of overflow
92	 */
93
94	/* Delay waiting for cpu, while runnable
95	 * count, delay_total NOT updated atomically
96	 */
97	__u64	cpu_count;
98	__u64	cpu_delay_total;
99
100	/* Following four fields atomically updated using task->delays->lock */
101
102	/* Delay waiting for synchronous block I/O to complete
103	 * does not account for delays in I/O submission
104	 */
105	__u64	blkio_count;
106	__u64	blkio_delay_total;
107
108	/* Delay waiting for page fault I/O (swap in only) */
109	__u64	swapin_count;
110	__u64	swapin_delay_total;
111
112	/* cpu "wall-clock" running time
113	 * On some architectures, value will adjust for cpu time stolen
114	 * from the kernel in involuntary waits due to virtualization.
115	 * Value is cumulative, in nanoseconds, without a corresponding count
116	 * and wraps around to zero silently on overflow
117	 */
118	__u64	cpu_run_real_total;
119
120	/* cpu "virtual" running time
121	 * Uses time intervals seen by the kernel i.e. no adjustment
122	 * for kernel's involuntary waits due to virtualization.
123	 * Value is cumulative, in nanoseconds, without a corresponding count
124	 * and wraps around to zero silently on overflow
125	 */
126	__u64	cpu_run_virtual_total;
127	/* Delay accounting fields end */
128	/* version 1 ends here */
129
130
1313) Extended accounting fields
132	/* Extended accounting fields start */
133
134	/* Accumulated RSS usage in duration of a task, in MBytes-usecs.
135	 * The current rss usage is added to this counter every time
136	 * a tick is charged to a task's system time. So, at the end we
137	 * will have memory usage multiplied by system time. Thus an
138	 * average usage per system time unit can be calculated.
139	 */
140	__u64	coremem;		/* accumulated RSS usage in MB-usec */
141
142  	/* Accumulated virtual memory usage in duration of a task.
143	 * Same as acct_rss_mem1 above except that we keep track of VM usage.
144	 */
145	__u64	virtmem;		/* accumulated VM usage in MB-usec */
146
147  	/* High watermark of RSS usage in duration of a task, in KBytes. */
148	__u64	hiwater_rss;		/* High-watermark of RSS usage */
149
150  	/* High watermark of VM  usage in duration of a task, in KBytes. */
151	__u64	hiwater_vm;		/* High-water virtual memory usage */
152
153	/* The following four fields are I/O statistics of a task. */
154	__u64	read_char;		/* bytes read */
155	__u64	write_char;		/* bytes written */
156	__u64	read_syscalls;		/* read syscalls */
157	__u64	write_syscalls;		/* write syscalls */
158
159	/* Extended accounting fields end */
160
161}
162