linux-kernel - RE: is it a timer bug?

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Message-ID: <F7C8A4D3A9905B45A80E4C194793FA6501C51D1352@PDSMSX501.ccr.corp.intel.com>
Date:	Mon, 15 Dec 2008 16:19:37 +0800
From:	"Shi, Alex" <alex.shi@...el.com>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: is it a timer bug?

OK, but my machine is not a production machine. 
A, 2.6.28-rc8 with tickles and highres
     PowerTOP version 1.9       (C) 2007 Intel Corporation

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        (65.1%)
C1                0.0ms ( 0.0%)
C2              105.8ms (34.9%)



Wakeups-from-idle per second :  3.8     interval: 5.0s
no ACPI power usage estimate available
B, 2.6.28-rc8 with tickless only 
     PowerTOP version 1.9       (C) 2007 Intel Corporation

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        (14.0%)
C1                0.0ms ( 0.0%)
C2                3.4ms (86.0%)



Wakeups-from-idle per second : 255.6    interval: 5.0s
no ACPI power usage estimate available

Top causes for wakeups:
  87.9% (267.6)       <interrupt> : extra timer interrupt
C, 2.6.27 with tickless only: 
    PowerTOP version 1.9       (C) 2007 Intel Corporation

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        (53.8%)         2.53 Ghz     0.0%
C1                0.0ms ( 0.0%)         2.53 Ghz    87.5%
C2              243.0ms (46.2%)         2.40 Ghz     0.0%
                                        1.60 Ghz    12.5%


Wakeups-from-idle per second :  2.2     interval: 30.0s
no ACPI power usage estimate available
I have checked the /proc/interrupts, the interrupt 0 is really triggered too much times. 
Brgs 
Alex 

>-----Original Message-----
>From: Arjan van de Ven [mailto:arjan@...radead.org]
>Sent: 2008年12月15日 16:09
>To: Shi, Alex
>Cc: linux-kernel@...r.kernel.org
>Subject: Re: is it a timer bug?
>
>On Mon, 15 Dec 2008 15:07:17 +0800
>"Shi, Alex" <alex.shi@...el.com> wrote:
>
>> I notice the timer interrupts is quit high on the 2.6.28-rc8 kernel
>> in my Nehalem machine. A, 180+/second timer interrupts in my Nehalem
>> machine with tickless enable. B, the timer interrupts reduce to
>> 10-/second with tickless and highres enable. On 2.6.27 kernel, the
>> timer interrupts can keep low with tickless kernel whenever the
>> highres feature is enable or not. So it is timer bug on my machine?
>>
>
>Hi,
>
>can you give us the powertop output of these production Core i7
>machines? That is the most likely way to get a clue about what is going
>on...
>
>Greetings,
>   Arjan van de Ven
>
>--
>Arjan van de Ven 	Intel Open Source Technology Centre
>For development, discussion and tips for power savings,
>visit http://www.lesswatts.org