From: Chuck Ebbert <cebbert@redhat.com>
To: Luca Tettamanti <kronos.it@gmail.com>
Cc: "Frans Pop" <elendil@planet.nl>, "Willy Tarreau" <w@1wt.eu>,
LKML <linux-kernel@vger.kernel.org>,
"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>,
"Alexander E. Patrakov" <patrakov@ums.usu.ru>
Subject: Re: Decreasing stime running confuses top
Date: Thu, 04 Oct 2007 15:32:23 -0400 [thread overview]
Message-ID: <47053FC7.2070308@redhat.com> (raw)
In-Reply-To: <20071004191921.GA24011@dreamland.darkstar.lan>
On 10/04/2007 03:19 PM, Luca Tettamanti wrote:
>>>>>> The latter seems to be utime ...decreasing. No wonder if
>>>>>> arithmetics will give strange results (probably top is using
>>>>>> unsigned delta?)...
>>>>> Hmm, minor miscounting from my side, stime seems more appropriate...
>>>> So, is it normal that stime decreases sometimes or a kernel bug?
>>>> /me expects the last...
>>> Let me guess... Dual core AMD64 ?
>> Nope: Intel(R) Pentium(R) D CPU 3.20GHz
>
> I just notice the same thing here, with a Core2 Duo (which is supposed
> to have synced TSCs) and working HPET.
>
>> The following may well be relevant.
>> With 2.6.22 and early 2.6.23-rc kernels (rc3-rc6) I often had this in my
>> kernel log (see http://lkml.org/lkml/2007/9/16/45):
>> checking TSC synchronization [CPU#0 -> CPU#1]:
>> Measured 248 cycles TSC warp between CPUs, turning off TSC clock.
>> Marking TSC unstable due to check_tsc_sync_source failed
>
> I don't see this though, TSCs are always syncronized between the 2
> cores.
>
Is CONFIG_VIRT_CPU_ACCOUNTING set?
next prev parent reply other threads:[~2007-10-04 19:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-03 12:33 top displaying 9999% CPU usage Frans Pop
2007-10-03 12:52 ` Jan Engelhardt
2007-10-03 13:03 ` Alexander E. Patrakov
2007-10-03 14:04 ` Frans Pop
2007-10-03 14:43 ` Ilpo Järvinen
2007-10-03 14:51 ` Ilpo Järvinen
2007-10-03 19:27 ` Decreasing stime running confuses top (was: top displaying 9999% CPU usage) Frans Pop
2007-10-03 20:24 ` Willy Tarreau
2007-10-03 23:32 ` Frans Pop
2007-10-04 19:19 ` Luca Tettamanti
2007-10-04 19:32 ` Chuck Ebbert [this message]
2007-10-04 20:00 ` Decreasing stime running confuses top Christian Borntraeger
2007-10-04 20:21 ` Chuck Ebbert
2007-10-04 21:10 ` [PATCH for testing] " Christian Borntraeger
2007-10-04 22:01 ` Chuck Ebbert
2007-10-04 22:31 ` Christian Borntraeger
2007-10-05 11:43 ` Luca
2007-10-05 15:07 ` Frans Pop
2007-10-05 15:49 ` Frans Pop
2007-10-08 16:49 ` Christian Borntraeger
2007-10-08 17:00 ` Ingo Molnar
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