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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-10-29 21:18:11 +0100
committerIngo Molnar <mingo@elte.hu>2007-10-29 21:18:11 +0100
commit73a2bcb0edb9ffb0b007b3546b430e2c6e415eee (patch)
treedd84f61589c7dd21b7be973c288611ffe547f21b
parentf7402e0361d4472535e07cfca648f2fa81d85cd2 (diff)
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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>
-rw-r--r--fs/proc/array.c3
-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/fork.c1
3 files changed, 4 insertions, 1 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 63c95af..d80baaa 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)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3c07d59..b0b1fe6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1009,6 +1009,7 @@ struct task_struct {
unsigned int rt_priority;
cputime_t utime, stime, utimescaled, stimescaled;
cputime_t gtime;
+ cputime_t prev_utime;
unsigned long nvcsw, nivcsw; /* context switch counts */
struct timespec start_time; /* monotonic time */
struct timespec real_start_time; /* boot based time */
diff --git a/kernel/fork.c b/kernel/fork.c
index ddafdfa..a65bfc4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1056,6 +1056,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->gtime = cputime_zero;
p->utimescaled = cputime_zero;
p->stimescaled = cputime_zero;
+ p->prev_utime = cputime_zero;
#ifdef CONFIG_TASK_XACCT
p->rchar = 0; /* I/O counter: bytes read */