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Message-ID: <Pine.LNX.4.64.0908141315310.1670@venus.araneidae.co.uk>
Date: Fri, 14 Aug 2009 13:18:08 +0100 (BST)
From: Michael Abbott <michael@...neidae.co.uk>
To: Jan Engelhardt <jengelh@...ozas.de>
cc: Martin Schwidefsky <schwidefsky@...ibm.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] Re: /proc/uptime idle counter remains at 0
Reviving this:
On Sat, 9 May 2009, Jan Engelhardt wrote:
> starting from v2.6.28-4930-g79741dd lasting thru at least v2.6.29.1,
> the second field of /proc/uptime always shows 0.00. This happens for
> both the typical i386 (my case) and on an ARM (according to Michael,
> cc'ed).
>
> >From the commit log of 79741dd:
>
> """The cpu time spent by the idle process actually doing
> something is currently accounted as idle time. This is plain
> wrong, the architectures that support VIRT_CPU_ACCOUNTING=y
> can do better: distinguish between the time spent doing
> nothing and the time spent by idle doing work. The first is
> accounted with account_idle_time and the second with
> account_system_time."""
>
> Citing Michael from our irc conversation:
>
> """the writer[committer] [says] that [the] idle process time
> isn't really idle time ... but that's all that /proc/uptime
> looks at. I guess fs/proc/uptime.c needs to catch up."""
>
> So, were the updates to uptime.c missed, or do we now live on with
> /proc/uptime constantly having 0?
My previous patch seems to have run into the sand. It every so nearly got
pulled into mainstream as far as I can tell, but didn't seem to make it;
no idea what happened.
So here we go again:
commit 6d67e34f45a92f347388e35bd84bf0361e660d3b
Author: Michael Abbott <michael.abbott@...mond.ac.uk>
Date: Mon May 11 07:14:19 2009 +0100
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. Further changes from commit e1c8053
are also included in this fix.
Signed-off-by: Michael Abbott <michael.abbott@...mond.ac.uk>
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 0c10a0b..be286b4 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -4,22 +4,32 @@
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/time.h>
+#include <linux/kernel_stat.h>
#include <asm/cputime.h>
+#include <asm/div64.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 i;
+ cputime64_t idle = cputime64_zero;
+ unsigned long int idle_mod;
+
+ for_each_possible_cpu(i) {
+ idle = cputime64_add(idle, kstat_cpu(i).cpustat.idle);
+#ifdef arch_idle_time
+ idle = cputime64_add(idle, arch_idle_time(i));
+#endif
+ }
+ idle = cputime64_to_clock_t(idle);
+ idle_mod = do_div(idle, 100);
do_posix_clock_monotonic_gettime(&uptime);
monotonic_to_bootbased(&uptime);
- cputime_to_timespec(idletime, &idle);
- seq_printf(m, "%lu.%02lu %lu.%02lu\n",
+ seq_printf(m, "%lu.%02lu %llu.%02lu\n",
(unsigned long) uptime.tv_sec,
(uptime.tv_nsec / (NSEC_PER_SEC / 100)),
- (unsigned long) idle.tv_sec,
- (idle.tv_nsec / (NSEC_PER_SEC / 100)));
+ idle, idle_mod);
return 0;
}
--
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