sched: keep utime/stime monotonic

keep utime/stime monotonic.

cpustats use utime/stime as a ratio against sum_exec_runtime, as a
consequence it can happen - when the ratio changes faster than time
accumulates - that either can be appear to go backwards.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 63c95afb561f..d80baaabf835 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -358,7 +358,8 @@ static cputime_t task_utime(struct task_struct *p)
         }
         utime = (clock_t)temp;
 
-        return clock_t_to_cputime(utime);
+        p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime));
+        return p->prev_utime;
 }
 
 static cputime_t task_stime(struct task_struct *p)