linux-kernel - Re: [PATCH] Re: /proc/uptime idle counter remains at 0

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Message-ID: <20090817062324.GN5039@cr0.nay.redhat.com>
Date:	Mon, 17 Aug 2009 14:23:24 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	Michael Abbott <michael@...neidae.co.uk>
Cc:	Amerigo Wang <xiyou.wangcong@...il.com>,
	Jan Engelhardt <jengelh@...ozas.de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Re: /proc/uptime idle counter remains at 0

On Mon, Aug 17, 2009 at 07:12:36AM +0100, Michael Abbott wrote:
>On Mon, 17 Aug 2009, Amerigo Wang wrote:
>> On Fri, Aug 14, 2009 at 01:18:08PM +0100, Michael Abbott wrote:
>> >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
>> 
>> 
>> This ugly #ifdef can be removed, check fs/proc/stat.c.
>
>I'm sorry?  Are you sure?  Here is what fs/proc/stat.c has to say:
>
>#ifndef arch_idle_time
>#define arch_idle_time(cpu) 0
>#endif
>...
>		idle = cputime64_add(idle, arch_idle_time(i));
>
>
>I think what you're actually saying is the #ifdef can be moved to 
>somewhere where it can be easily missed.  For this very reason, I'd rather 
>be more explicit about it.

Yes, indeed.

I was suggesting to move that #ifdef into some header so that
both two files can use it. For me, this is the better fix.

Thanks.
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