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Date: Wed, 25 Feb 2004 16:39:20 -0500
From: David Ford <david+challenge-response@blue-labs.org>
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To: linux-kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: /proc or ps tools bug?  2.6.3, time is off
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powerix root # grep cpu /proc/stat; cat /proc/uptime
cpu  403880 466666 580559 15017904 475868 10864 3030
cpu0 403880 466666 580559 15017904 475868 10864 3030
186882.63 154999.74

(gdb) p 403880 +466666 +580559 +15017904 +475868 +10864 +3030
$1 = 16958771

(gdb) p 16958771/186882.63
$2 = 90.745571164104447

Hmm, not quite 100.0

david

Petri Kaukasoina wrote:

>Hi,
>
>I reported the same problem some time ago. Could you type
>
>grep cpu /proc/stat; cat /proc/uptime
>
>for example, I get
>
>cpu  140708 1489 43735 21209021 292168 4879 4192
>cpu0 140708 1489 43735 21209021 292168 4879 4192
>216925.15 215037.34
>
>Then add jiffies and divide by uptime:
>
>(140708+1489+43735+21209021+292168+4879+4192)/216925.15 = 100.01695
>
>which is not 100 here as it should be. (On kernel 2.2.* I have it exactly
>100). ps uses Hertz=100 but it should be 170 ppm larger which makes an error
>of about 15 seconds a day. (Running without ntpd doesn't fix it.)
>  
>