-stable review patch. If anyone has any objections, please let us know.
------------------
From: Frans Pop <[email protected]>
sched: 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.
Combined backport for 2.6.23 of the following patches from mainline:
commit 73a2bcb0edb9ffb0b007b3546b430e2c6e415eee
Author: Peter Zijlstra <[email protected]>
sched: keep utime/stime monotonic
commit 9301899be75b464ef097f0b5af7af6d9bd8f68a7
Author: Balbir Singh <[email protected]>
sched: fix /proc/<PID>/stat stime/utime monotonicity, part 2
Signed-off-by: Frans Pop <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Balbir Singh <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/proc/array.c | 6 ++++--
include/linux/sched.h | 1 +
kernel/fork.c | 2 ++
3 files changed, 7 insertions(+), 2 deletions(-)
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -351,7 +351,8 @@ static cputime_t task_utime(struct task_
}
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)
@@ -366,7 +367,8 @@ static cputime_t task_stime(struct task_
stime = nsec_to_clock_t(p->se.sum_exec_runtime) -
cputime_to_clock_t(task_utime(p));
- return clock_t_to_cputime(stime);
+ p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime));
+ return p->prev_stime;
}
#endif
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1022,6 +1022,7 @@ struct task_struct {
unsigned int rt_priority;
cputime_t utime, stime;
+ cputime_t prev_utime, prev_stime;
unsigned long nvcsw, nivcsw; /* context switch counts */
struct timespec start_time; /* monotonic time */
struct timespec real_start_time; /* boot based time */
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1045,6 +1045,8 @@ static struct task_struct *copy_process(
p->utime = cputime_zero;
p->stime = cputime_zero;
+ p->prev_utime = cputime_zero;
+ p->prev_stime = cputime_zero;
#ifdef CONFIG_TASK_XACCT
p->rchar = 0; /* I/O counter: bytes read */
--
-
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