[PATCH] add context switch counters

From: Peter Chubb <peterc@gelato.unsw.edu.au>

Currently, the context switch counters reported by getrusage() are
always zero.  The appended patch adds fields to struct task_struct to
count context switches, and adds code to do the counting.

The patch adds 4 longs to struct task struct, and a single addition to
the fast path in schedule().

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 054168543a45..3c6e3129144d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -391,6 +391,7 @@ struct task_struct {
 	struct timer_list real_timer;
 	struct list_head posix_timers; /* POSIX.1b Interval Timers */
 	unsigned long utime, stime, cutime, cstime;
+	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw; /* context switch counts */
 	u64 start_time;
 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
 	unsigned long min_flt, maj_flt, nswap, cmin_flt, cmaj_flt, cnswap;