[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>

4 files changed, 207 insertions, 21 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 */
+
+}
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 */
diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index 47c71daa416f..db443221ba5b 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -20,6 +20,7 @@
 #include <linux/sched.h>
 #include <linux/tsacct_kern.h>
 #include <linux/acct.h>
+#include <linux/jiffies.h>
 
 
 #define USEC_PER_TICK   (USEC_PER_SEC/HZ)
@@ -62,33 +63,35 @@ void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk)
         stats->ac_stime  = cputime_to_msecs(tsk->stime) * USEC_PER_MSEC;
         stats->ac_minflt = tsk->min_flt;
         stats->ac_majflt = tsk->maj_flt;
-        /* Each process gets a minimum of one usec cpu time */
-        if ((stats->ac_utime == 0) && (stats->ac_stime == 0)) {
-                stats->ac_stime = 1;
-        }
 
         strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm));
 }
 
 
 #ifdef CONFIG_TASK_XACCT
+
+#define KB 1024
+#define MB (1024*KB)
 /*
  * fill in extended accounting fields
  */
 void xacct_add_tsk(struct taskstats *stats, struct task_struct *p)
 {
-        stats->acct_rss_mem1 = p->acct_rss_mem1;
-        stats->acct_vm_mem1  = p->acct_vm_mem1;
+        /* convert pages-jiffies to Mbyte-usec */
+        stats->coremem = jiffies_to_usecs(p->acct_rss_mem1) * PAGE_SIZE / MB;
+        stats->virtmem = jiffies_to_usecs(p->acct_vm_mem1) * PAGE_SIZE / MB;
         if (p->mm) {
-                stats->hiwater_rss   = p->mm->hiwater_rss;
-                stats->hiwater_vm    = p->mm->hiwater_vm;
+                /* adjust to KB unit */
+                stats->hiwater_rss   = p->mm->hiwater_rss * PAGE_SIZE / KB;
+                stats->hiwater_vm    = p->mm->hiwater_vm * PAGE_SIZE / KB;
         }
         stats->read_char        = p->rchar;
         stats->write_char       = p->wchar;
         stats->read_syscalls    = p->syscr;
         stats->write_syscalls   = p->syscw;
 }
-
+#undef KB
+#undef MB
 
 /**
  * acct_update_integrals - update mm integral fields in task_struct
@@ -97,8 +100,8 @@ void xacct_add_tsk(struct taskstats *stats, struct task_struct *p)
 void acct_update_integrals(struct task_struct *tsk)
 {
         if (likely(tsk->mm)) {
-                long delta =
-                        cputime_to_jiffies(tsk->stime) - tsk->acct_stimexpd;
+                long delta = cputime_to_jiffies(
+                        cputime_sub(tsk->stime, tsk->acct_stimexpd));
 
                 if (delta == 0)
                         return;