ALSA: bad sound with low CPU load

ALSA: bad sound with low CPU load

[Aaron Burt]

Basically, sound comes out as a hissing, garbled mess *unless* I load
down the CPU.  A kernel compile seems to do nicely for this purpose.

I've been seeing this behavior in the late 2.6.0-pre kernels through
2.6.1 plain and -mm1.  It happens with preempt and HPET both enabled
and disabled.  I haven't yet found what exact kernel version the
problem starts with, and I get no sound with the OSS drivers, so I
can't test them ATM.  I plan to narrow things down if possible, but
that takes time.

System is an Athlon at 1145 MHz on an ECS K7S5A (SiS 735 chipset)
running Debian Sid with ALSA-base v0.9.8-3.  The problem happens both
with the onboard i810-compatible sound and a CM8738 PCI sound board.
(Note that both are fixed at 48000 Hz.)  I'm tempted to buy 'n' try a
SoundBlaster-PCI card from FreeGeek.

I'd be happy to provide further info, but didn't want to start out
with a super-long message for something that may be obvious, if not
visible in Google or LKML.  Please reply to the list; I'm subscribed.

Thanks in advance,
  Aaron

Re: ALSA: bad sound with low CPU load

[Prakash K. Cheemplavam]

Aaron Burt wrote:
> Basically, sound comes out as a hissing, garbled mess *unless* I load
> down the CPU.  A kernel compile seems to do nicely for this purpose.

Is CPU Disconnect on? Turn if off and maybe it is OK then. (It was like 
this in Windows with Via KT133 Chipset.)

Try using athcool.

Prakash

Re: ALSA: bad sound with low CPU load

[Aaron Burt]

"Prakash K. Cheemplavam" <PrakashKC@gmx.de> wrote:
> Aaron Burt wrote:
>> Basically, sound comes out as a hissing, garbled mess *unless* I load
>> down the CPU.  A kernel compile seems to do nicely for this purpose.
>
> Is CPU Disconnect on? Turn if off and maybe it is OK then. (It was like 
> this in Windows with Via KT133 Chipset.)
>
> Try using athcool.

You got it in one!  "athcool off" fixes the sound, "athcool on" breaks
it again.  

Updating my rcfiles,
  Aaron

Re: ALSA: bad sound with low CPU load

[Frank v Waveren]

On Fri, Jan 09, 2004 at 11:23:35PM +0000, Aaron Burt wrote:
> Basically, sound comes out as a hissing, garbled mess *unless* I load
> down the CPU.  A kernel compile seems to do nicely for this purpose.
Is it a garbled mess or a 1000Hz background tone? I get the latter on
the onboard audio of my A7N8X motherboard too, it's interference from
the timer interrupt. Not sure if it's power load related or EM
interference, but I strongly suspect it'll go away if you turn off
making idle calls in the kernel config. Going back to 100Hz (or up to
10000Hz as someone submitted a patch for a while back) will probably
make the problem go away too.

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