[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>

2 files changed, 32 insertions, 10 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4ddeb0f982fb..7ef899c47c29 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -984,7 +984,7 @@ struct task_struct {
 #if defined(CONFIG_TASK_XACCT)
         u64 acct_rss_mem1;      /* accumulated rss usage */
         u64 acct_vm_mem1;       /* accumulated virtual memory usage */
-        clock_t acct_stimexpd;  /* clock_t-converted stime since last update */
+        cputime_t acct_stimexpd;/* stime since last update */
 #endif
 #ifdef CONFIG_NUMA
         struct mempolicy *mempolicy;
diff --git a/include/linux/taskstats.h b/include/linux/taskstats.h
index 3d2c304886b0..45248806ae9c 100644
--- a/include/linux/taskstats.h
+++ b/include/linux/taskstats.h
@@ -32,14 +32,21 @@
 
 
 #define TASKSTATS_VERSION       2
-#define TS_COMM_LEN             16      /* should sync up with TASK_COMM_LEN
+#define TS_COMM_LEN             32      /* should be >= TASK_COMM_LEN
                                          * in linux/sched.h */
 
 struct taskstats {
 
-        /* Version 1 */
+        /* 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;
-        __u32   ac_exitcode;    /* Exit status */
+        __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 */
         __u8    ac_nice;                /* task_nice */
 
@@ -104,15 +111,30 @@ struct taskstats {
         __u64   ac_etime;               /* Elapsed time [usec] */
         __u64   ac_utime;               /* User CPU time [usec] */
         __u64   ac_stime;               /* SYstem CPU time [usec] */
-        __u64   ac_minflt;              /* Minor Page Fault */
-        __u64   ac_majflt;              /* Major Page Fault */
+        __u64   ac_minflt;              /* Minor Page Fault Count */
+        __u64   ac_majflt;              /* Major Page Fault Count */
         /* Basic Accounting Fields end */
 
         /* Extended accounting fields start */
-        __u64   acct_rss_mem1;          /* accumulated rss usage */
-        __u64   acct_vm_mem1;           /* accumulated virtual memory usage */
-        __u64   hiwater_rss;            /* High-watermark of RSS usage */
-        __u64   hiwater_vm;             /* High-water virtual memory usage */
+        /* 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 and virtual memory usage in duration of
+         * a task, in KBytes.
+         */
+        __u64   hiwater_rss;            /* High-watermark of RSS usage, in KB */
+        __u64   hiwater_vm;             /* High-water VM usage, in KB */
+
+        /* 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 */