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SubjectRe: [PATCH] Re: /proc/uptime idle counter remains at 0
On Mon, 11 May 2009, Michael Abbott wrote:
> So as a simple solution, I've attached a patch where I just copy the
> idle field processing from fs/proc/stat.c. I expect that on a
> multi-processor machine things may not be quite so simple -- as up time
> is in elapsed wall-clock time, then so should idle time be, so we
> probably need to also divide by the number of processors. Afraid I
> don't have a multiprocessor test system, and /proc/stat seems ok, so
> I've not made this refinement.

To hopefully help, I've rebased the patch onto current git
(fs/proc/uptime.c has undergone some unrelated changes).

Date: Mon, 11 May 2009 07:14:19 +0100
Subject: [PATCH] Fix idle time field in /proc/uptime

Git commit 79741dd changes idle cputime accounting, but unfortunately
the /proc/uptime file hasn't caught up. Here the idle time calculation
from /proc/stat is copied over.

Signed-off-by: Michael Abbott <>
fs/proc/uptime.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 0c10a0b..0f43395 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -4,13 +4,19 @@
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/time.h>
+#include <linux/kernel_stat.h>
#include <asm/cputime.h>

static int uptime_proc_show(struct seq_file *m, void *v)
struct timespec uptime;
struct timespec idle;
- cputime_t idletime = cputime_add(init_task.utime, init_task.stime);
+ int len, i;
+ cputime_t idletime = 0;
+ for_each_possible_cpu(i)
+ idletime = cputime64_add(idletime, kstat_cpu(i).cpustat.idle);
+ idletime = cputime64_to_clock_t(idletime);


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