13 Nov
2006
13 Nov
'06
12:12 p.m.
As always when blaming someone it turns out this has absolutely nothing
to do with the supposed culprit. Apparently, my lower-end Dell notebook
has a singing capacitor, which gets induced by the jack daemon calling
an interrupt, as indicated by the frequency of the noise problem
correlating to the jack buffer size. Interestingly, the noise is not
audible when the system is under some load.
My current approach is to find a load generator that will place a little
load on the system to make the hum go away while still leaving some room
for softsynths.
The next best approach is replacing the darn thing.
Of course, a kernel based fix would be, how should I say, shmoozy.
Carlo
13 Nov
13 Nov
1:07 p.m.
New subject: [linux-audio-user] Wanted: Singing Capacitor Fix (was: blaming Jack)
Am Montag, 13. November 2006 17:11 schrieb Carlo Capocasa:
As always when blaming someone it turns out this has
absolutely nothing
to do with the supposed culprit. Apparently, my lower-end Dell notebook
has a singing capacitor, which gets induced by the jack daemon calling
an interrupt, as indicated by the frequency of the noise problem
correlating to the jack buffer size. Interestingly, the noise is not
audible when the system is under some load.
My current approach is to find a load generator that will place a little
load on the system to make the hum go away while still leaving some room
for softsynths.
A simple load generator with low scheduling priority:
echo 'for ((;1;)); do i=0; done;'|nice -n 19 sh
Run it in a shell.
Stop it with Ctrl+C.
No need for kernel fix here ;-)
Karsten
14 Nov
14 Nov
1:07 p.m.
New subject: [linux-audio-user] Re: Wanted: Singing Capacitor Fix (was: blaming Jack)
echo 'for ((;1;)); do i=0; done;'|nice -n 19
sh
Shazam, dude shazam. The noise is gone.
Together with the ground loop, this thing has been causing me headaches for FOUR
YEARS. And now it's gone. Thank you.
Carlo
2:29 p.m.
New subject: [linux-audio-user] Re: Wanted: Singing Capacitor Fix (was: blaming Jack)
On Tue, Nov 14, 2006 at 05:05:57PM +0000, Carlo Capocasa wrote:
Somehow this just jogged my memory... have you tried the "nohlt" kernel
boot parameter? Maybe totally irrelevant. I haven't used it since I got
a nice quiet Delta 66, but it used to be mandatory to reduce
video-related noise with my older hardware.
There seem to be several variants depending on architecture...
from /usr/src/linux/Documentation/kernel-parameters.txt:
nohlt [BUGS=ARM]
no-hlt [BUGS=IA-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
use it.
nohalt [IA-64] Tells the kernel not to use the power
saving function PAL_HALT_LIGHT when idle. This increases
power-consumption. On the positive side, it reduces interrupt wake-up
latency, which may improve performance in certain
environments such as networked servers or real-time systems.
--
Paul Winkler
http://www.slinkp.com
echo 'for ((;1;)); do i=0; done;'|nice
-n 19 sh
Shazam, dude shazam. The noise is gone.
Together with the ground loop, this thing has been causing me headaches for FOUR
YEARS. And now it's gone. Thank you.
11:57 p.m.
New subject: [linux-audio-user] Re: Wanted: Singing Capacitor Fix (was: blaming Jack)
Hi Paul!
Boy, I was thinking 'Kernel Patch' when I said kernel fix, all along
with recompiling kernels and testing and hoping it will go with all the
other patches I need and hoping it will get included soon and so on and
so forth; while I would rather be producing music.
And then you came up and brought up 'Kernel Parameter'. That's just
beautiful.
If there exists a kernel parameter that will solve this issue you can
bet that I will find it, if I have to learn every line of the linux
kernel by heart... IN BINARY MACHINE CODE.
nohlt [BUGS=ARM]
no-hlt [BUGS=IA-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
use it.
nohalt [IA-64] Tells the kernel not to use the power
I tried nohlt and no-hlt but they didn't have any effect on the noise. I
did a "grep -r nohlt /proc" and it mentioned something about a nohlt, so
I would assume I made no mistakes in configuring grub properly.
Thanks again, Paul, this is great.
Carlo
6586
days inactive
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days old
linux-audio-user@lists.linuxaudio.org
4 comments
3 participants
participants (3)
-
Carlo Capocasa -
Karsten Wiese -
Paul Winkler