linux/Documentation/accounting/taskstats-struct.txt
Jay Lan db5fed26b2 [PATCH] csa accounting taskstats update
ChangeLog:
   Feedbacks from Andrew Morton:
   - define TS_COMM_LEN to 32
   - change acct_stimexpd field of task_struct to be of
     cputime_t, which is to be used to save the tsk->stime
     of last timer interrupt update.
   - a new Documentation/accounting/taskstats-struct.txt
     to describe fields of taskstats struct.

   Feedback from Balbir Singh:
   - keep the stime of a task to be zero when both stime
     and utime are zero as recoreded in task_struct.

   Misc:
   - convert accumulated RSS/VM from platform dependent
     pages-ticks to MBytes-usecs in the kernel

Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jes Sorensen <jes@sgi.com>
Cc: Chris Sturtivant <csturtiv@sgi.com>
Cc: Tony Ernst <tee@sgi.com>
Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:29 -07:00

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The struct taskstats
--------------------
This document contains an explanation of the struct taskstats fields.
There are three different groups of fields in the struct taskstats:
1) Common and basic accounting fields
If CONFIG_TASKSTATS is set, the taskstats inteface is enabled and
the common fields and basic accounting fields are collected for
delivery at do_exit() of a task.
2) Delay accounting fields
These fields are placed between
/* Delay accounting fields start */
and
/* Delay accounting fields end */
Their values are collected if CONFIG_TASK_DELAY_ACCT is set.
3) Extended accounting fields
These fields are placed between
/* Extended accounting fields start */
and
/* Extended accounting fields end */
Their values are collected if CONFIG_TASK_XACCT is set.
Future extension should add fields to the end of the taskstats struct, and
should not change the relative position of each field within the struct.
struct taskstats {
1) Common and basic accounting fields:
/* The version number of this struct. This field is always set to
* TAKSTATS_VERSION, which is defined in <linux/taskstats.h>.
* Each time the struct is changed, the value should be incremented.
*/
__u16 version;
/* The exit code of a task. */
__u32 ac_exitcode; /* Exit status */
/* The accounting flags of a task as defined in <linux/acct.h>
* Defined values are AFORK, ASU, ACOMPAT, ACORE, and AXSIG.
*/
__u8 ac_flag; /* Record flags */
/* The value of task_nice() of a task. */
__u8 ac_nice; /* task_nice */
/* The name of the command that started this task. */
char ac_comm[TS_COMM_LEN]; /* Command name */
/* The scheduling discipline as set in task->policy field. */
__u8 ac_sched; /* Scheduling discipline */
__u8 ac_pad[3];
__u32 ac_uid; /* User ID */
__u32 ac_gid; /* Group ID */
__u32 ac_pid; /* Process ID */
__u32 ac_ppid; /* Parent process ID */
/* The time when a task begins, in [secs] since 1970. */
__u32 ac_btime; /* Begin time [sec since 1970] */
/* The elapsed time of a task, in [usec]. */
__u64 ac_etime; /* Elapsed time [usec] */
/* The user CPU time of a task, in [usec]. */
__u64 ac_utime; /* User CPU time [usec] */
/* The system CPU time of a task, in [usec]. */
__u64 ac_stime; /* System CPU time [usec] */
/* The minor page fault count of a task, as set in task->min_flt. */
__u64 ac_minflt; /* Minor Page Fault Count */
/* The major page fault count of a task, as set in task->maj_flt. */
__u64 ac_majflt; /* Major Page Fault Count */
2) Delay accounting fields:
/* Delay accounting fields start
*
* All values, until the comment "Delay accounting fields end" are
* available only if delay accounting is enabled, even though the last
* few fields are not delays
*
* xxx_count is the number of delay values recorded
* xxx_delay_total is the corresponding cumulative delay in nanoseconds
*
* xxx_delay_total wraps around to zero on overflow
* xxx_count incremented regardless of overflow
*/
/* Delay waiting for cpu, while runnable
* count, delay_total NOT updated atomically
*/
__u64 cpu_count;
__u64 cpu_delay_total;
/* Following four fields atomically updated using task->delays->lock */
/* Delay waiting for synchronous block I/O to complete
* does not account for delays in I/O submission
*/
__u64 blkio_count;
__u64 blkio_delay_total;
/* Delay waiting for page fault I/O (swap in only) */
__u64 swapin_count;
__u64 swapin_delay_total;
/* cpu "wall-clock" running time
* On some architectures, value will adjust for cpu time stolen
* from the kernel in involuntary waits due to virtualization.
* Value is cumulative, in nanoseconds, without a corresponding count
* and wraps around to zero silently on overflow
*/
__u64 cpu_run_real_total;
/* cpu "virtual" running time
* Uses time intervals seen by the kernel i.e. no adjustment
* for kernel's involuntary waits due to virtualization.
* Value is cumulative, in nanoseconds, without a corresponding count
* and wraps around to zero silently on overflow
*/
__u64 cpu_run_virtual_total;
/* Delay accounting fields end */
/* version 1 ends here */
3) Extended accounting fields
/* Extended accounting fields start */
/* Accumulated RSS usage in duration of a task, in MBytes-usecs.
* The current rss usage is added to this counter every time
* a tick is charged to a task's system time. So, at the end we
* will have memory usage multiplied by system time. Thus an
* average usage per system time unit can be calculated.
*/
__u64 coremem; /* accumulated RSS usage in MB-usec */
/* Accumulated virtual memory usage in duration of a task.
* Same as acct_rss_mem1 above except that we keep track of VM usage.
*/
__u64 virtmem; /* accumulated VM usage in MB-usec */
/* High watermark of RSS usage in duration of a task, in KBytes. */
__u64 hiwater_rss; /* High-watermark of RSS usage */
/* High watermark of VM usage in duration of a task, in KBytes. */
__u64 hiwater_vm; /* High-water virtual memory usage */
/* The following four fields are I/O statistics of a task. */
__u64 read_char; /* bytes read */
__u64 write_char; /* bytes written */
__u64 read_syscalls; /* read syscalls */
__u64 write_syscalls; /* write syscalls */
/* Extended accounting fields end */
}