[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>

1 files changed, 161 insertions, 0 deletions

diff --git a/Documentation/accounting/taskstats-struct.txt b/Documentation/accounting/taskstats-struct.txt
new file mode 100644
index 000000000000..661c797eaf79
--- /dev/null
+++ b/Documentation/accounting/taskstats-struct.txt
@@ -0,0 +1,161 @@
+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 */
+
+}