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Documentation / accounting / taskstats-struct.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:00 EST.

1	The struct taskstats
2	--------------------
3	
4	This document contains an explanation of the struct taskstats fields.
5	
6	There are three different groups of fields in the struct taskstats:
7	
8	1) Common and basic accounting fields
9	    If CONFIG_TASKSTATS is set, the taskstats interface is enabled and
10	    the common fields and basic accounting fields are collected for
11	    delivery at do_exit() of a task.
12	2) 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.
18	3) 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	
25	4) Per-task and per-thread context switch count statistics
26	
27	5) Time accounting for SMT machines
28	
29	6) Extended delay accounting fields for memory reclaim
30	
31	Future extension should add fields to the end of the taskstats struct, and
32	should not change the relative position of each field within the struct.
33	
34	
35	struct taskstats {
36	
37	1) Common and basic accounting fields:
38		/* The version number of this struct. This field is always set to
39		 * TAKSTATS_VERSION, which is defined in <linux/taskstats.h>.
40		 * Each time the struct is changed, the value should be incremented.
41		 */
42		__u16	version;
43	
44	  	/* The exit code of a task. */
45		__u32	ac_exitcode;		/* Exit status */
46	
47	  	/* The accounting flags of a task as defined in <linux/acct.h>
48		 * Defined values are AFORK, ASU, ACOMPAT, ACORE, and AXSIG.
49		 */
50		__u8	ac_flag;		/* Record flags */
51	
52	  	/* The value of task_nice() of a task. */
53		__u8	ac_nice;		/* task_nice */
54	
55	  	/* The name of the command that started this task. */
56		char	ac_comm[TS_COMM_LEN];	/* Command name */
57	
58	  	/* The scheduling discipline as set in task->policy field. */
59		__u8	ac_sched;		/* Scheduling discipline */
60	
61		__u8	ac_pad[3];
62		__u32	ac_uid;			/* User ID */
63		__u32	ac_gid;			/* Group ID */
64		__u32	ac_pid;			/* Process ID */
65		__u32	ac_ppid;		/* Parent process ID */
66	
67	  	/* The time when a task begins, in [secs] since 1970. */
68		__u32	ac_btime;		/* Begin time [sec since 1970] */
69	
70	  	/* The elapsed time of a task, in [usec]. */
71		__u64	ac_etime;		/* Elapsed time [usec] */
72	
73	  	/* The user CPU time of a task, in [usec]. */
74		__u64	ac_utime;		/* User CPU time [usec] */
75	
76	  	/* The system CPU time of a task, in [usec]. */
77		__u64	ac_stime;		/* System CPU time [usec] */
78	
79	  	/* The minor page fault count of a task, as set in task->min_flt. */
80		__u64	ac_minflt;		/* Minor Page Fault Count */
81	
82		/* The major page fault count of a task, as set in task->maj_flt. */
83		__u64	ac_majflt;		/* Major Page Fault Count */
84	
85	
86	2) Delay accounting fields:
87		/* Delay accounting fields start
88		 *
89		 * All values, until the comment "Delay accounting fields end" are
90		 * available only if delay accounting is enabled, even though the last
91		 * few fields are not delays
92		 *
93		 * xxx_count is the number of delay values recorded
94		 * xxx_delay_total is the corresponding cumulative delay in nanoseconds
95		 *
96		 * xxx_delay_total wraps around to zero on overflow
97		 * xxx_count incremented regardless of overflow
98		 */
99	
100		/* Delay waiting for cpu, while runnable
101		 * count, delay_total NOT updated atomically
102		 */
103		__u64	cpu_count;
104		__u64	cpu_delay_total;
105	
106		/* Following four fields atomically updated using task->delays->lock */
107	
108		/* Delay waiting for synchronous block I/O to complete
109		 * does not account for delays in I/O submission
110		 */
111		__u64	blkio_count;
112		__u64	blkio_delay_total;
113	
114		/* Delay waiting for page fault I/O (swap in only) */
115		__u64	swapin_count;
116		__u64	swapin_delay_total;
117	
118		/* cpu "wall-clock" running time
119		 * On some architectures, value will adjust for cpu time stolen
120		 * from the kernel in involuntary waits due to virtualization.
121		 * Value is cumulative, in nanoseconds, without a corresponding count
122		 * and wraps around to zero silently on overflow
123		 */
124		__u64	cpu_run_real_total;
125	
126		/* cpu "virtual" running time
127		 * Uses time intervals seen by the kernel i.e. no adjustment
128		 * for kernel's involuntary waits due to virtualization.
129		 * Value is cumulative, in nanoseconds, without a corresponding count
130		 * and wraps around to zero silently on overflow
131		 */
132		__u64	cpu_run_virtual_total;
133		/* Delay accounting fields end */
134		/* version 1 ends here */
135	
136	
137	3) Extended accounting fields
138		/* Extended accounting fields start */
139	
140		/* Accumulated RSS usage in duration of a task, in MBytes-usecs.
141		 * The current rss usage is added to this counter every time
142		 * a tick is charged to a task's system time. So, at the end we
143		 * will have memory usage multiplied by system time. Thus an
144		 * average usage per system time unit can be calculated.
145		 */
146		__u64	coremem;		/* accumulated RSS usage in MB-usec */
147	
148	  	/* Accumulated virtual memory usage in duration of a task.
149		 * Same as acct_rss_mem1 above except that we keep track of VM usage.
150		 */
151		__u64	virtmem;		/* accumulated VM usage in MB-usec */
152	
153	  	/* High watermark of RSS usage in duration of a task, in KBytes. */
154		__u64	hiwater_rss;		/* High-watermark of RSS usage */
155	
156	  	/* High watermark of VM  usage in duration of a task, in KBytes. */
157		__u64	hiwater_vm;		/* High-water virtual memory usage */
158	
159		/* The following four fields are I/O statistics of a task. */
160		__u64	read_char;		/* bytes read */
161		__u64	write_char;		/* bytes written */
162		__u64	read_syscalls;		/* read syscalls */
163		__u64	write_syscalls;		/* write syscalls */
164	
165		/* Extended accounting fields end */
166	
167	4) Per-task and per-thread statistics
168		__u64	nvcsw;			/* Context voluntary switch counter */
169		__u64	nivcsw;			/* Context involuntary switch counter */
170	
171	5) Time accounting for SMT machines
172		__u64	ac_utimescaled;		/* utime scaled on frequency etc */
173		__u64	ac_stimescaled;		/* stime scaled on frequency etc */
174		__u64	cpu_scaled_run_real_total; /* scaled cpu_run_real_total */
175	
176	6) Extended delay accounting fields for memory reclaim
177		/* Delay waiting for memory reclaim */
178		__u64	freepages_count;
179		__u64	freepages_delay_total;
180	}
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