[LAU] noise problem, need some help

[Dave Phillips]

Greetings,

Recently my computer rebooted after a power outage and after having an
uptime of many months. I'm running Fedora 23 here, with Fernando's rt
kernel from Planet CCRMA, on hardware that includes an AMD FX6300, 16G
memory, a big hard drive, and nVidia graphics. For those months of
uptime I've enjoyed a smooth-running system with very few issues. The
CPU runs in performance mode, and as far as I can tell the system has
been sweetly optimized for realtime audio.

Alas, after rebooting I now have extremely annoying issues with noise
from my wireless mouse when running VCV Rack, which is a problem I never
had before the reboot. I suspect IRQ assignment, but I'm awfully rusty
at troubleshooting so I'm asking the group for advice.

My checklist so far:

1. Running the correct kernel ?

Linux The6300 4.6.7-200.rt14.1.fc23.ccrma.x86_64+rt #1 SMP PREEMPT RT
Sat Oct 1 16:06:12 PDT 2016 x86_64 x86_64 x86_64 GNU/Linux

2. CPU in Performance mode ?

'cat /proc/cpuinfo' reports 'cpu MHz: 3500.000' for all cores

3. rtprio set ?

$ rtirq status

PID CLS RTPRIO NI PRI %CPU STAT COMMAND
169 FF 70 - 110 0.0 S irq/8-rtc0
748 FF 69 - 109 0.0 S irq/19-snd_hda_
764 FF 69 - 109 2.0 S irq/20-snd_ice1
166 FF 68 - 108 0.0 S irq/1-i8042
85 FF 50 - 90 0.0 S irq/9-acpi
138 FF 50 - 90 0.0 S irq/22-ahci[000
150 FF 50 - 90 0.0 S irq/17-ehci_hcd
151 FF 50 - 90 0.0 S irq/19-ehci_hcd
153 FF 50 - 90 0.0 S irq/16-ohci_hcd
154 FF 50 - 90 0.0 S irq/16-ohci_hcd
155 FF 50 - 90 0.0 S irq/18-ohci_hcd
156 FF 50 - 90 0.0 S irq/18-ohci_hcd
159 FF 50 - 90 0.0 S irq/18-ohci_hcd
430 FF 50 - 90 0.0 S irq/14-pata_ati
431 FF 50 - 90 0.0 S irq/15-pata_ati
706 FF 50 - 90 0.0 S irq/7-parport0
1062 FF 50 - 90 0.0 S irq/26-enp2s0
1178 FF 50 - 90 0.8 S irq/27-nvidia
...


Permissions are correct, and I have already tried switching the wireless
dongle to a different USB port. So what am I missing, what have I
forgotten ? The machine is the same as before the reboot, the kernel is
the same, and as far as I can tell the audio system is the same as it
ever was. I'm at a bit of a loss here, any and all help will be
appreciated.

Best regards,

dp

[David Kastrup]

Post by Dave Phillips
Greetings,
Recently my computer rebooted after a power outage and after having an
uptime of many months. I'm running Fedora 23 here, with Fernando's rt
kernel from Planet CCRMA, on hardware that includes an AMD FX6300, 16G
memory, a big hard drive, and nVidia graphics. For those months of
uptime I've enjoyed a smooth-running system with very few issues. The
CPU runs in performance mode, and as far as I can tell the system has
been sweetly optimized for realtime audio.
Alas, after rebooting I now have extremely annoying issues with noise
from my wireless mouse when running VCV Rack, which is a problem I
never had before the reboot. I suspect IRQ assignment, but I'm awfully
rusty at troubleshooting so I'm asking the group for advice.

Do you have a wired mouse or other pointing device (does not sound like
a laptop or there would be a few available) for comparison? I imagine
"noise from my wireless mouse" to refer to mouse _movements_ and those
do not just exercise the mouse and its USB connection but also the mouse
cursor display. If the problem is actually with the graphics
controller, using a different pointing device could provide a clue.

[Ralf Mardorf]

Post by David Kastrup
to refer to mouse _movements_

Dave Phillips, do you hear the mouse when moving and/or using the mouse
wheel? That's what most of us likely guess. Or do you hear noise, even
if you do not use the mouse, that stops, if the mouse is disconnected?

While nowadays even cheap consumer audio interfaces have an amazing good
signal-to-noise ratio, even expensive audio interfaces suffer from
computer noise.

Even a damaged (not completely broken) headphone cable shield could be
the cause for allegedly unexplainable computer noise in the audio
signal.

Most of the times I order something from my semi-conductor dealer, I buy
ahead a few very cheap 1⁄4 inch (6.35 millimetres) jacks. Just a few,
since the quality of those cheap jacks isn't always the same and apart
from this, I tend to use expensive jacks (ream and neutrik) for stressed
cables, but at least better jacks than the very cheap jacks. Sometimes
very cheap jacks are ok, sometimes they get borked, if they just see a
soldering iron at a distance. My point is that sometimes just cleaning
jack sockets, replacing jacks or damaged cables, does reduce computer
noise. Keep in mind that a connection could become too dirty or cable
gets damaged etc. randomly at the same time you update software or you
reboot. The noise not necessarily is related to an update or restart,
even if it started at the same time.

[Dave Phillips]

Post by David Kastrup
Do you have a wired mouse or other pointing device (does not sound like
a laptop or there would be a few available) for comparison? I imagine
"noise from my wireless mouse" to refer to mouse _movements_ and those
do not just exercise the mouse and its USB connection but also the mouse
cursor display. If the problem is actually with the graphics
controller, using a different pointing device could provide a clue.

Thanks, David, I'll try to find another mouse around here.

Meanwhile, I discovered that Rack's sample rate had been changed from
48kHz to 44.1. Changing it back to 48 has helped.

Best,

dp