Hello.
I tried playing with some audio apps like JACK and fluidsynth, and noticed the
following. If I set the parameters in JACK so that the latency becomes less
than ~10 milliseconds, a faint tone appears in the headphones connected to the
onboard sound card.
I guess that its frequency is the tone is the same as that of the interrupts
generated by the sound card. The tone disappears if I run something like
"while : ; do : ; done" that consumes CPU time continuously, so I guess this
has something to do with the power-saving features and less-than-perfect PSU.
My question is: what are my options (like kernel parameters) to disable power-
saving features, other than running such CPU-eating process continuously?
--
Alexander E. Patrakov
On Wednesday 24 December 2008 11:16:57 you wrote:
> On Wed, 2008-12-24 at 10:50 +0500, Alexander E. Patrakov wrote:
> > My question is: what are my options (like kernel parameters) to disable
> > power- saving features, other than running such CPU-eating process
> > continuously?
>
> You can set your performance governor to "performance". If you're using
> KDE, in the lower right corner of your display is an icon for that. I
> don't know what Gnome looks like. Anyway, you can set it manually as
> well...
>
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
I don't have the cpufreq driver loaded normally, so these files don't exist.
And this is my home desktop, not the corporate laptop. After modprobing
"cpufreq-acpi", the file does appear and contains "performance". The tone
doesn't disappear, though.
--
Alexander E. Patrakov
Alexander E. Patrakov wrote:
> Hello.
>
> I tried playing with some audio apps like JACK and fluidsynth, and noticed the
> following. If I set the parameters in JACK so that the latency becomes less
> than ~10 milliseconds, a faint tone appears in the headphones connected to the
> onboard sound card.
>
> I guess that its frequency is the tone is the same as that of the interrupts
> generated by the sound card. The tone disappears if I run something like
> "while : ; do : ; done" that consumes CPU time continuously, so I guess this
> has something to do with the power-saving features and less-than-perfect PSU.
>
> My question is: what are my options (like kernel parameters) to disable power-
> saving features, other than running such CPU-eating process continuously?
You can try booting with idle=poll on kernel command line, so the CPU
will not enter halt states..
On Wednesday 24 December 2008 12:02:53 Robert Hancock wrote:
> Alexander E. Patrakov wrote:
> > Hello.
> >
> > I tried playing with some audio apps like JACK and fluidsynth, and
> > noticed the following. If I set the parameters in JACK so that the
> > latency becomes less than ~10 milliseconds, a faint tone appears in the
> > headphones connected to the onboard sound card.
> >
> > I guess that its frequency is the tone is the same as that of the
> > interrupts generated by the sound card. The tone disappears if I run
> > something like "while : ; do : ; done" that consumes CPU time
> > continuously, so I guess this has something to do with the power-saving
> > features and less-than-perfect PSU.
> >
> > My question is: what are my options (like kernel parameters) to disable
> > power- saving features, other than running such CPU-eating process
> > continuously?
>
> You can try booting with idle=poll on kernel command line, so the CPU
> will not enter halt states..
This mostly helped. Now the tone disappeared, but there are noises (not
xruns!) caused by the onboard graphics card when KDE4 draws something. I
disabled the effects to reduce the noise, but it didn't fully help (there is
still some "zzzzz" when I move the mouse over the taskbar so that different
window buttons are highlighted). The noise exists both in the connector for
headphones on the front panel, and in the green connector at the back of the
computer, but in the second connector, it is much softer.
The board is Intel DG965SS, and the graphics ship is:
00:02.0 0300: 8086:29a2 (rev 02)
00:02.1 0380: 8086:29a3 (rev 02)
or, with names instead of the numbers,
00:02.0 VGA compatible controller: Intel Corporation 82G965 Integrated
Graphics Controller (rev 02)
00:02.1 Display controller: Intel Corporation 82G965 Integrated Graphics
Controller (rev 02)
Intel developers: could you please add some workaround to the "intel" driver,
so that the GPU always stays busy (and thus draws the constant amount of
power)? And please tell the hardware designers so that for the future boards,
this interference between graphics and audio should not happen. Add separate
stabilizers and filters for the power supply of the audio chip, carefully
design the wiring so that the "noisy" lines don't get near anything related to
audio.
--
Alexander E. Patrakov
Alexander E. Patrakov wrote:
> On Wednesday 24 December 2008 12:02:53 Robert Hancock wrote:
>> Alexander E. Patrakov wrote:
>>> Hello.
>>>
>>> I tried playing with some audio apps like JACK and fluidsynth, and
>>> noticed the following. If I set the parameters in JACK so that the
>>> latency becomes less than ~10 milliseconds, a faint tone appears in the
>>> headphones connected to the onboard sound card.
>>>
>>> I guess that its frequency is the tone is the same as that of the
>>> interrupts generated by the sound card. The tone disappears if I run
>>> something like "while : ; do : ; done" that consumes CPU time
>>> continuously, so I guess this has something to do with the power-saving
>>> features and less-than-perfect PSU.
>>>
>>> My question is: what are my options (like kernel parameters) to disable
>>> power- saving features, other than running such CPU-eating process
>>> continuously?
>> You can try booting with idle=poll on kernel command line, so the CPU
>> will not enter halt states..
>
> This mostly helped. Now the tone disappeared, but there are noises (not
> xruns!) caused by the onboard graphics card when KDE4 draws something. I
> disabled the effects to reduce the noise, but it didn't fully help (there is
> still some "zzzzz" when I move the mouse over the taskbar so that different
> window buttons are highlighted). The noise exists both in the connector for
> headphones on the front panel, and in the green connector at the back of the
> computer, but in the second connector, it is much softer.
>
> The board is Intel DG965SS, and the graphics ship is:
>
> 00:02.0 0300: 8086:29a2 (rev 02)
> 00:02.1 0380: 8086:29a3 (rev 02)
>
> or, with names instead of the numbers,
>
> 00:02.0 VGA compatible controller: Intel Corporation 82G965 Integrated
> Graphics Controller (rev 02)
> 00:02.1 Display controller: Intel Corporation 82G965 Integrated Graphics
> Controller (rev 02)
>
> Intel developers: could you please add some workaround to the "intel" driver,
> so that the GPU always stays busy (and thus draws the constant amount of
> power)? And please tell the hardware designers so that for the future boards,
> this interference between graphics and audio should not happen. Add separate
> stabilizers and filters for the power supply of the audio chip, carefully
> design the wiring so that the "noisy" lines don't get near anything related to
> audio.
>
I think you may be expecting too much from the analog output quality for
onboard sound, this is a common problem on many boards. If you really
want high quality analog output you usually have to go for a separate
sound card which usually have much better filtering.