[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 4ddeb0f982f..7ef899c47c2 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 3d2c304886b..45248806ae9 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 */