problem with ALSA on AMD64 w/VIA chipset

problem with ALSA on AMD64 w/VIA chipset

[Eric Sharkey]

Hi all,

I posted on alsa-user a while back, but I think I need developer
assistance with this.

There seems to be a problem with Alsa when running on the AMD64
architecture on motherboards with the Via K8T800 chipset.  The sound
is highly irregular, with lots of drop-outs, but also speed-ups,
slow-downs and weird volume changes.

I've got this problem on an Asus K8V SE motherboard.  Rod Smith
has the same problem on an MSI Neo-FSR.
(http://groups.google.com/groups?q=%22asus+k8v%22+alsa&hl=en&lr=&c2coff=1&selm=1et59c-90v.ln%40speaker.rodsbooks.com&rnum=4)

In that post, Rod thought the problem was the Alsa driver for the
on-board sound (VIA VT8237), but this is not the case, as I've installed
a PCI Trident 4DWave NX, and it shows exactly the same behavior.
The problem appears not to be in the low level driver code, but
something higher.

The degree of the problem is highly sensitive to the load on the
CPU at the time.  Games like bumprace, which use multiple threads
and never sleep (giving load values around 8), sound awful.  Most
games like tuxkart, which keep the load under 1, sound perfectly fine.

And yet, some things sound bad even when the CPU isn't loaded.
timidity++ is a good example.

This happens with both 64 and 32 bit kernels, and no amount of
twiddling with kernel parameters (ACPI/CPU frequency scaling, apic,
preemption, etc.) seems to make any difference.

Can anyone here offer a suggestion?

Eric


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now. 
http://productguide.itmanagersjournal.com/

Re: problem with ALSA on AMD64 w/VIA chipset

[Takashi Iwai]

[-- Attachment #1: Type: text/plain, Size: 1872 bytes --]

At Mon, 22 Nov 2004 10:30:21 -0500,
Eric Sharkey wrote:
> 
> 
> Hi all,
> 
> I posted on alsa-user a while back, but I think I need developer
> assistance with this.
> 
> There seems to be a problem with Alsa when running on the AMD64
> architecture on motherboards with the Via K8T800 chipset.  The sound
> is highly irregular, with lots of drop-outs, but also speed-ups,
> slow-downs and weird volume changes.
> 
> I've got this problem on an Asus K8V SE motherboard.  Rod Smith
> has the same problem on an MSI Neo-FSR.
> (http://groups.google.com/groups?q=%22asus+k8v%22+alsa&hl=en&lr=&c2coff=1&selm=1et59c-90v.ln%40speaker.rodsbooks.com&rnum=4)
> 
> In that post, Rod thought the problem was the Alsa driver for the
> on-board sound (VIA VT8237), but this is not the case, as I've installed
> a PCI Trident 4DWave NX, and it shows exactly the same behavior.
> The problem appears not to be in the low level driver code, but
> something higher.
> 
> The degree of the problem is highly sensitive to the load on the
> CPU at the time.  Games like bumprace, which use multiple threads
> and never sleep (giving load values around 8), sound awful.  Most
> games like tuxkart, which keep the load under 1, sound perfectly fine.
> 
> And yet, some things sound bad even when the CPU isn't loaded.
> timidity++ is a good example.

The current trident driver seems buggy with 2 periods.
The patch below is a workwround (not a right fix, though).


> This happens with both 64 and 32 bit kernels, and no amount of
> twiddling with kernel parameters (ACPI/CPU frequency scaling, apic,
> preemption, etc.) seems to make any difference.

Hmm, I just thought of cpurfreq, but your report sounds that it's not
the case.  Could you unload powernow-k8 module just to be sure?

I think you'd better to ask this on LKML, since the symptom looks like
the kernel core problem.


Takashi

[-- Attachment #2: Type: text/plain, Size: 725 bytes --]

Index: alsa-kernel/pci/trident/trident_main.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/pci/trident/trident_main.c,v
retrieving revision 1.59
diff -u -r1.59 trident_main.c
--- alsa-kernel/pci/trident/trident_main.c	30 Jul 2004 12:44:59 -0000	1.59
+++ alsa-kernel/pci/trident/trident_main.c	11 Oct 2004 15:24:30 -0000
@@ -814,7 +814,7 @@
 
 	/* voice management */
 
-	if (params_buffer_size(hw_params) / 2 != params_period_size(hw_params)) {
+	if (1 /*params_buffer_size(hw_params) / 2 != params_period_size(hw_params)*/) {
 		if (evoice == NULL) {
 			evoice = snd_trident_alloc_voice(trident, SNDRV_TRIDENT_VOICE_TYPE_PCM, 0, 0);
 			if (evoice == NULL)

Re: problem with ALSA on AMD64 w/VIA chipset

[Eric Sharkey]

> > This happens with both 64 and 32 bit kernels, and no amount of
> > twiddling with kernel parameters (ACPI/CPU frequency scaling, apic,
> > preemption, etc.) seems to make any difference.
> 
> Hmm, I just thought of cpurfreq, but your report sounds that it's not
> the case.  Could you unload powernow-k8 module just to be sure?

I've spent a good deal of time trying to track this down over the
last couple of months.  I've compiled and booted under more configurations
than I care to count.  I'm absolutely certain that with a kernel
with no power management support at all, and all power management turned
off in the bios, the problem still persists.

> I think you'd better to ask this on LKML, since the symptom looks like
> the kernel core problem.

Hmm.  Ok.

If there's something you can think of that I could do to gather more
information to help diagnose the problem, please let me know.

Thanks,

Eric


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now. 
http://productguide.itmanagersjournal.com/