linux-kernel - Re: Buggy idle time reported in /proc/uptime for SMP systems?

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Message-ID: <20071018191256.GA29046@linux.vnet.ibm.com>
Date:	Fri, 19 Oct 2007 00:42:56 +0530
From:	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
To:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org, pbadari@...ibm.com,
	dhaval@...ux.vnet.ibm.com
Subject: Re: Buggy idle time reported in /proc/uptime for SMP systems?

On Thu, Oct 18, 2007 at 09:55:13PM +0530, Srivatsa Vaddagiri wrote:
> The idle time reported in /proc/uptime (2nd field) seems to be the idle
> time of only CPU0. Shouldn't it reflect the total idle time on a SMP system? 
> Do folks agree that it is a bug that needs to be fixed? If so, will send
> a patch ...

On further reflection, it doesn't sound buggy. Reporting idle time across all
cpus in /proc/uptime will cause idle time > uptime, which will be odd. I
guess if anyone wants strict idle time from all cpus, they can always
look at /proc/stat.

> Fyi, I see patches submitted to fix this way back in 2001
> [http://lkml.org/lkml/2001/3/17/55], but don't think they made in ..

-- 
Regards,
vatsa
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