strange buzzing sound after the 2.6.10 patch

strange buzzing sound after the 2.6.10 patch

[Jing Su]

Hello,

I vaguely remember someone else mentioning this problem on the list
before, but I don't recall if there were any answers to the solution.

I'm running a vanilla 2.6.10 kernel patched with the acpi-2005-01-25 patch.  

When running the patched kernel, I noticed that my laptop makes a very
strange and faint buzzing sound.  I've determined that the buzzing
sound is somewhat related to CPU and HD load.  When the CPU load is
heavy, or when the HD is busy, the buzzing stops.  But when the system
idles, the buzzing continues.  I've also tried forcing the HD to go
into suspension using hdparm, but the buzzing continues.

Any hints or clues?
If this problem hasn't been encountered before, I'd appreciate it if
someone could give hints for how I can best go about isolating the
problem.

-Jing


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Re: strange buzzing sound after the 2.6.10 patch

[Jeremy Moles]

Try this:

edit /usr/src/linux/include/asm/param.h and change HZ to 100 (instead of
1000). Other folks here can perhaps comment on the side-effects, though
I've noticed few I couldn't handle. Perhaps a divide by 0 warning with
some programs that "guess" at the HZ, but other than that...

You'll find it only happens when the processor ACPI module is loaded. Go
figure.

On Wed, 2005-02-23 at 21:31 -0500, Jing Su wrote:
> Hello,
> 
> I vaguely remember someone else mentioning this problem on the list
> before, but I don't recall if there were any answers to the solution.
> 
> I'm running a vanilla 2.6.10 kernel patched with the acpi-2005-01-25 patch.  
> 
> When running the patched kernel, I noticed that my laptop makes a very
> strange and faint buzzing sound.  I've determined that the buzzing
> sound is somewhat related to CPU and HD load.  When the CPU load is
> heavy, or when the HD is busy, the buzzing stops.  But when the system
> idles, the buzzing continues.  I've also tried forcing the HD to go
> into suspension using hdparm, but the buzzing continues.
> 
> Any hints or clues?
> If this problem hasn't been encountered before, I'd appreciate it if
> someone could give hints for how I can best go about isolating the
> problem.
> 
> -Jing
> 
> 
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> _______________________________________________
> Acpi-devel mailing list
> Acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> https://lists.sourceforge.net/lists/listinfo/acpi-devel



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Re: strange buzzing sound after the 2.6.10 patch

[Thomas Renninger]

Jeremy Moles wrote:
> Try this:
> 
> edit /usr/src/linux/include/asm/param.h and change HZ to 100 (instead of
> 1000). Other folks here can perhaps comment on the side-effects, though
> I've noticed few I couldn't handle. Perhaps a divide by 0 warning with
> some programs that "guess" at the HZ, but other than that...
> 
> You'll find it only happens when the processor ACPI module is loaded. Go
> figure.
> 
> On Wed, 2005-02-23 at 21:31 -0500, Jing Su wrote:
> 
>>Hello,
>>
>>I vaguely remember someone else mentioning this problem on the list
>>before, but I don't recall if there were any answers to the solution.
>>
>>I'm running a vanilla 2.6.10 kernel patched with the acpi-2005-01-25 patch.  
>>
>>When running the patched kernel, I noticed that my laptop makes a very
>>strange and faint buzzing sound.  I've determined that the buzzing
>>sound is somewhat related to CPU and HD load.  When the CPU load is
>>heavy, or when the HD is busy, the buzzing stops.  But when the system
>>idles, the buzzing continues.  I've also tried forcing the HD to go
>>into suspension using hdparm, but the buzzing continues.
>>
>>Any hints or clues?
>>If this problem hasn't been encountered before, I'd appreciate it if
>>someone could give hints for how I can best go about isolating the
>>problem.

I heard it is because of switching C-states 1000 times a second.
Loading the processor module with max_cstates=1 or 2 should work.


      Thomas


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Re: strange buzzing sound after the 2.6.10 patch

[Jos Delbar]

Jing,

Chances are that your laptop has imperfect electrical components that will 
oscillate and cause a buzzing sound under certain conditions. An example of 
such a condition is when ACPI promotes the processor to a higher C state in 
order to save power. This is why you only notice the buzzing sound when the 
processor is idle.

With recent ACPI patches you can control the maximum C state through 
the /sys/module/processor/parameters/max_cstate file. For example:

echo 2 > /sys/module/processor/parameters/max_cstate

To get an idea of which C states are causing the buzzing sound, watch the 
"usage" fields in the /proc/acpi/processor/CPU0/power file.

You can also set the limit using the processor module parameter max_cstate at 
boot time (or module load time).

-- 

- Jos Delbar
  jos.delbar-Cru1EgDzd7c@public.gmane.org


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