taskstats: add context-switch counters

Make available to the user the following task and process performance
statistics:

	* Involuntary Context Switches (task_struct->nivcsw)
	* Voluntary Context Switches (task_struct->nvcsw)

Statistics information is available from:
	1. taskstats interface (Documentation/accounting/)
	2. /proc/PID/status (task only).

This data is useful for detecting hyperactivity patterns between processes.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Maxim Uvarov <muvarov@ru.mvista.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Cc: Jonathan Lim <jlim@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/linux/taskstats.h b/include/linux/taskstats.h
index a46104a28f66..dce1ed204972 100644
--- a/include/linux/taskstats.h
+++ b/include/linux/taskstats.h
@@ -31,7 +31,7 @@
  */
 
 
-#define TASKSTATS_VERSION       4
+#define TASKSTATS_VERSION       5
 #define TS_COMM_LEN             32      /* should be >= TASK_COMM_LEN
                                          * in linux/sched.h */
 
@@ -149,6 +149,9 @@ struct taskstats {
         __u64   read_bytes;             /* bytes of read I/O */
         __u64   write_bytes;            /* bytes of write I/O */
         __u64   cancelled_write_bytes;  /* bytes of cancelled write I/O */
+
+        __u64  nvcsw;                   /* voluntary_ctxt_switches */
+        __u64  nivcsw;                  /* nonvoluntary_ctxt_switches */
 };