linux-kernel - Re: v2.6.26-rc7: Negative powertop values

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Date:	Sat, 21 Jun 2008 23:22:09 +0200
From:	"Vegard Nossum" <vegard.nossum@...il.com>
To:	"Arjan van de Ven" <arjan@...ux.intel.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"Peter Zijlstra" <a.p.zijlstra@...llo.nl>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: v2.6.26-rc7: Negative powertop values

On Sat, Jun 21, 2008 at 11:16 PM, Arjan van de Ven
<arjan@...ux.intel.com> wrote:
> On Sat, 21 Jun 2008 21:16:37 +0200
> "Vegard Nossum" <vegard.nossum@...il.com> wrote:
>> I was testing v2.6.26-rc7 by running lmbench and hotplug/-unplugging
>> CPUs and a few other programs at the same time. Powertop was showing a
>> negative number of wakeups/second and average C3 residency was
>> something really insane. Is there anything strange with this schedstat
>> file, or is there another file I should look at that can explain the
>> strange powertop numbers? Or maybe it's just an artifact of powertop
>> and this has nothing to do with the kernel?
>
> powertop doesn't assume you do cpu hotunplug (and the internal state
> goes wacky if you do).
>

Oh right :-) Are there any plans to support this?

> [I assume you know that doing a software unplug you burn more power
> than by leaving the cpu idle]

Well, yeah, this was purely to exercise the kernel a bit, IOW testing.
I guess this can be signed off as a non-kernel issue, then. Thanks for
the quick reply!


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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