[LAU] help request: RT audio checkup and xorg's xruns

david gnome at hawaii.rr.com
Wed Aug 26 06:37:09 CEST 2020

I looked up your Asus on their site. I found no information about the 
Intel graphics controller there. I know many OLD Intel graphics 
controllers used shared system memory for video - that's slower than 
dedicated memory as part of the controller. I don't know if that Intel 
controller has its own memory or not.

The NVidia GTX 850M has its own dedicated video memory, much faster than 
system memory.

But I really don't know if video memory has anything to do with getting 
xruns when running videos. One possibility might be to switch to using 
the Nouveau driver. According to its specs, the NVidia controller has 
hardware support for decoding a lot of video codecs. Which means the 
graphics adapter would be handling the decoding. That might or might not 
fix the xruns.

I don't know how to do that. I found this page about it:


I'm guessing that if installing or reinstalling the nouveau driver 
doesn't change the setting, you can change it using the instructions 
here "Under Configuring the X Server", it has a conf file to add to the 
Xorg configuration:


Section "Device"
     Identifier "n"
     Driver "nouveau"

My laptop has an NVIDIA GeForce GTX 1650 in it but I haven't tried using 
that yet. I'm not sure Nouveau supports the GPU I have.

On 8/24/20 7:16 AM, Nicola Pandini wrote:
> Thank you David,
> I kept i8042 in RTIRQ_NAME_LIST because it was present in the default 
> configuration of rtirq. I have now removed it from RTIRQ_NAME_LIST, 
> but the situation doesn't seem to have changed.
> Shared memory:
> I don't know how to find it, could you please tell me how to check it out?
> Here is the lspci for the video interface:
> 00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core 
> Processor Integrated Graphics Controller (rev 06) (prog-if 00 [VGA 
> controller])
>     Subsystem: ASUSTeK Computer Inc. 4th Gen Core Processor Integrated 
> Graphics Controller
>     Flags: bus master, fast devsel, latency 0, IRQ 36
>     Memory at f7400000 (64-bit, non-prefetchable) [size=4M]
>     Memory at d0000000 (64-bit, prefetchable) [size=256M]
>     I/O ports at f000 [size=64]
>     [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
>     Capabilities: <access denied>
>     Kernel driver in use: i915
>     Kernel modules: i915
> 01:00.0 3D controller: NVIDIA Corporation GM107M [GeForce GTX 850M] 
> (rev a2)
>     Subsystem: ASUSTeK Computer Inc. GM107M [GeForce GTX 850M]
>     Flags: bus master, fast devsel, latency 0, IRQ 255
>     Memory at f6000000 (32-bit, non-prefetchable) [size=16M]
>     Memory at e0000000 (64-bit, prefetchable) [size=256M]
>     Memory at f0000000 (64-bit, prefetchable) [size=32M]
>     I/O ports at e000 [size=128]
>     Expansion ROM at f7000000 [disabled] [size=512K]
>     Capabilities: <access denied>
>     Kernel modules: nouveau
> Il 23/08/20 06:35, David W. Jones ha scritto:
>> I don't know about the rest of the settings, but why is i8042 (PS/2 
>> keyboard/mouse controller) on the RTIRQ_NAME_LIST?
>> Does the laptop use shared system memory for video?
>> On August 22, 2020 12:29:58 PM HST, Nicola Pandini 
>> <nicola.pandini at gmail.com> wrote:
>>     Hello list!
>>     I have a setup that I use in my live sets made with an ASUS N551 laptops
>>     and a NI Komplete Audio 6, which allows me to play without XRUNS at 64
>>     frames / period with a modular approach (Qtractor, LinuxSampler,
>>     Yoshimi, SooperLooper, PureData).
>>     The whole thing runs on Debian Stretch with AVLinux 4.9.47-rt37avl2 kernel.
>>     I am quite happy with the performance of this setup, but I started
>>     having XRUNS when I added real-time video management as well. Those
>>     issues made me notice that the system runs without XRUNS only if XOrg is
>>     not stressed much, while it starts producing XRUNS when I play a video,
>>     or when I open the browser, or even when I quickly move or resize a window.
>>     I would like to understand if the problem is due to an incorrect
>>     configuration of realtime priorities, or to something that I have not
>>     yet managed to trap.
>>     I currently use these configurations:
>>     [Xorg]
>>     The video driver is i915.
>>     I read on the internet that:
>>     "If your graphic card was manufactured in 2007 and newer, try
>>     uninstalling the xserver-xorg-video-intel package and use the builtin
>>     modesetting driver (xserver-xorg-core) instead"
>>     Questions:
>>     - I uninstalled xserver-xorg-video-intel, but I still see the i915
>>     driver: is that correct, or should I see another driver?
>>     [rtirq]
>>     RTIRQ_NAME_LIST = "snd usb i8042"
>>     RTIRQ_PRIO_HIGH = 90
>>     RTIRQ_PRIO_DECR = 5
>>     RTIRQ_PRIO_LOW = 51
>>     RTIRQ_RESET_ALL = 0
>>     RTIRQ_NON_THREADED = "rtc snd"
>>     Questions:
>>     - rtc must be in "NON_THREADED", or in "RTIRQ_NAME_LIST"?
>>     - in "RTIRQ_NAME_LIST" can I remove "usb" and put only the item that
>>     manages my USB card? Should it be xhci?
>>     - can i take i8042 off the list?
>>     - is it recommended to use RTIRQ_RESET_ALL = 1 to override all other IRQs?
>>     [jackd]
>>     jackd -P83 -dalsa -dhw: K6 -r44100 -p64 -n2 -I1
>>     Questions:
>>     - the priority must be lower than those that are set to the IRQs by rtirq?
>>     [limits.conf]
>>     @audio - rtprio 99 # maximum realtime priority
>>     @audio - memlock unlimited # maximum locked-in-memory address space (KB)
>>     Questions:
>>     - what is the recommended value of rtprio in 2020? On the internet I
>>     find 90, 95 and 99
>>     Can you help me do a checkup of my configuration?
>>     Thanks!
>> ------------------------------------------------------------------------

David W. Jones
gnome at hawaii.rr.com
authenticity, honesty, community
"My password is the last 8 digits of π."

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