Annoying whitenoise sound coming from snd_hda enabled chipset

[Ben Kaduk]

2009/7/28 Yoshihiro Ota <ota at j.email.ne.jp>:
> On Fri, 24 Jul 2009 01:23:18 +0200
> Ståle Lyngaas <staale at lyngaas.com> wrote:
>
>> On Sat, Feb 21, 2009 at 11:01 AM, Garrett Cooper<yanefbsd at gmail.com> wrote:
>> >    I don't know how else to describe it, but when I turn up my
>> > speakers enough (50%+) and don't have any sound playing, I hear a
>> > whitenoise hiss coming out of them. When I change webpages (nvidia
>> > driver is GIANT locked) or do something else kernel intensive it stops
>> > for a brief second, but apart from that it's an annoying trill sound
>> > almost like a mosquito humming around me waiting to be swatted.
>>
>> I suspect this is due to the CPU executing the HLT instruction.
>>
>> Try running the following command:
>>     sysctl machdep.cpu_idle_hlt=0
>>
>> --
>> Ståle Lyngaas
>
> I couldn't find such a sysctl.
> The close one was machdep.cpu_hlt.

Setting machdep.idle from acpi to spin make my problems go away.
(None of the other options (mwait, mwait_hlt, hlt, acpi) helped.)

-Ben Kaduk