Faked real time kernels? Wrong compiled? (Solved!)

[taersh]

Just for anyone's interest:

Both the kernels, 5.4.5-rt3 and 5.11.4-rt11 doesn't seem to be real time kernels.
Running real time configuration check on both of them returns: Kernel with real time preempt NOT FOUND!
I checked it right now, as I did not understand why there's so many Xruns.
After I switched back to 5.0.21-rt15 which is the real time kernel from the latest Studio 1337 by Iowt3ch,
real time configuration scan returns: Kernel with real time preempt FOUND.

[Flash]

Where did you find these fake kernels? Should this be in the thread announcing those kernels?

[rockedge]

@taersh Yes I'm interested. How did you test them and with what tools? Both of these kernel versions have had the full real time patches and AUFS5 patches successfully applied and compiled with PREMEPT and FULL RT enabled. Weird that my benchmark tests show they are running in real time and are PREEMPT ready.

I would like to test them using the methods you did to double check them. Otherwise I will remove them from being available.

From the 5.4.5-rt3 kernel's DOT config file: ( http://rockedge.org/kernels/data/kernel ... _64-030120 )

Code: Select all

# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y

This is for the Full Real Time ->

Code: Select all

CONFIG_PREEMPT_NOTIFIERS=y
CONFIG_ASN1=y
CONFIG_UNINLINE_SPIN_UNLOCK=y
CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=y
CONFIG_MUTEX_SPIN_ON_OWNER=y
CONFIG_RWSEM_SPIN_ON_OWNER=y
CONFIG_LOCK_SPIN_ON_OWNER=y
CONFIG_ARCH_USE_QUEUED_SPINLOCKS=y
CONFIG_QUEUED_SPINLOCKS=y
CONFIG_ARCH_USE_QUEUED_RWLOCKS=y
CONFIG_QUEUED_RWLOCKS=y
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE=y
CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE=y
CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y
CONFIG_FREEZER=y

Same with the 5.11.4-rt11 kernel -> http://rockedge.org/kernels/data/kernel ... _64-130321

fake kernels

what does that mean exactly?

[taersh]

Hi.

I can say that at least one of those kernels I downloaded somewhere from rockedge's pages.
Tested both of them using the realtime-config-quickscan tools which is a set of PERL scripts.

The results of this realtime configuration scan seems to be all well, so far.
Except:

- real time preempt not found --- NOT GOOD
- running as root -- NOT GOOD

Everything else of my Audio/MIDI settings returned GOOD on the scan.
Using the kernel from latest Studio 1337 3.3 it complains only about running as root.

I'm trying to get rid of all those Xruns as there's sometimes a lot of them affecting the sound coming out of the speakers.
My heart starts beating each time if it happens, and I doubt this would be caused by running as root.
However, I got Xruns also with Studio 1337 3.3 kernel.

Maybe I got some wrong hardware in my new machine???

[rockedge]

I will try out this set https://github.com/raboof/realtimeconfigquickscan to run tests.

Not sure why these 2 kernels are not testing well. I will look into it.

[taersh]

My current version of realtime config quickscan was downloaded sometimes at the beginning of 2020.
Right now I downloaded the latest version of realtime config quickscan and made a scan. It seems to be alright now.

Code: Select all

== GUI-enabled checks ==
Checking if you are root... yes - not good
You are running this script as root. Please run it as a regular user for the most reliable results.
Checking filesystem 'noatime' parameter... 5.11.4 kernel - good
(relatime is default since 2.6.30)
cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu10/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu11/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu4/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu5/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu6/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu7/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu8/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
cat: /sys/devices/system/cpu/cpu9/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
Checking CPU Governors... CPU 0: '' CPU 1: '' CPU 10: '' CPU 11: '' CPU 2: '' CPU 3: '' CPU 4: '' CPU 5: '' CPU 6: '' CPU 7: '' CPU 8: '' CPU 9: ''  - not good
Set CPU Governors to 'performance' with 'cpupower frequency-set -g performance' or 'cpufreq-set -c <cpunr> -g performance' (Debian/Ubuntu)
See also: http://linuxmusicians.com/viewtopic.php?f=27&t=844
Checking swappiness... 10 - good
Checking for resource-intensive background processes... none found - good
Checking checking sysctl inotify max_user_watches... >= 524288 - good
Checking whether you're in the 'audio' group... yes - good
Checking for multiple 'audio' groups... no - good
Checking the ability to prioritize processes with chrt... yes - good
Checking kernel support for high resolution timers... found - good
Kernel with Real-Time Preemption... 'threadirqs' kernel parameter - good
Checking if kernel system timer is high-resolution... found - good
Checking kernel support for tickless timer... found - good
== Other checks ==
Checking filesystem types... ok.
** Set $SOUND_CARD_IRQ to the IRQ of your soundcard to enable more checks.
   Find your sound card's IRQ by looking at '/proc/interrupts' and lspci.

Command uname -a also says PREEMPT

Code: Select all

root# uname -a
Linux puppypc1448 5.11.4-rt11 #1 SMP PREEMPT Sat Mar 13 18:36:56 EST 2021 x86_64 x86_64 x86_64 GNU/Linux
root#

This is still confusing why there are so many Xruns...

[taersh]

Hmm, this is still more confusing:

Code: Select all

root# grep -e "CONFIG_IRQ_FORCED_THREADING=y" -e "CONFIG_PREEMPT_RT=y" /boot/config-`uname -r`
CONFIG_IRQ_FORCED_THREADING=y
root#

It should return: CONFIG_IRQ_FORCED_THREADING=y and CONFIG_PREEMPT_RT=y

[rockedge]

@taersh I think I found what is happening. The full real time patches did not complete 100% successfully so the kernels are PREEMPT enabled for low latency BUT are not full real time.

I re-compiled from scratch 5.11.4-rt11 and 5.4.5-rt3 and both show PREEMPT enable option but NOT the full rt option. Seems one or more patches are not being applied correctly but not crashing the build process.

I wonder if these PREEMPT enabled kernels with the CPU frequency set to performance operate with as low of a latency as the full real time kernels.

Have you tried the 5.4.70-rt40 full real time kernel?

[taersh]

Have you tried the 5.4.70-rt40 full real time kernel?

No, I don't have that one.
Where to download?

[rockedge]

No, I don't have that one.
Where to download?

Here is the direct link to the huge kernel file -> http://rockedge.org/kernels/data/kernel ... 64.tar.bz2

or look in http://rockedge.org/kernels under "kernel->64bit->5.4.70-rt40-full-rt_x64"

[taersh]

Output of realtime config quickscan for 5.4.70-rt40:

Code: Select all

== GUI-enabled checks ==
Checking if you are root... yes - not good
You are running this script as root. Please run it as a regular user for the most reliable results.
Checking filesystem 'noatime' parameter... 5.4.70 kernel - good
(relatime is default since 2.6.30)
cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor: Datei oder Verzeichnis nicht gefunden
...
Checking CPU Governors... CPU 0: '' CPU 1: '' CPU 10: '' CPU 11: '' CPU 2: '' CPU 3: '' CPU 4: '' CPU 5: '' CPU 6: '' CPU 7: '' CPU 8: '' CPU 9: ''  - not good
Set CPU Governors to 'performance' with 'cpupower frequency-set -g performance' or 'cpufreq-set -c <cpunr> -g performance' (Debian/Ubuntu)
See also: http://linuxmusicians.com/viewtopic.php?f=27&t=844
Checking swappiness... 10 - good
Checking for resource-intensive background processes... none found - good
Checking checking sysctl inotify max_user_watches... >= 524288 - good
Checking whether you're in the 'audio' group... yes - good
Checking for multiple 'audio' groups... no - good
Checking the ability to prioritize processes with chrt... yes - good
Checking kernel support for high resolution timers... found - good
Kernel with Real-Time Preemption... found - good
Checking if kernel system timer is high-resolution... found - good
Checking kernel support for tickless timer... found - good
== Other checks ==
Checking filesystem types... ok.
** Set $SOUND_CARD_IRQ to the IRQ of your soundcard to enable more checks.
   Find your sound card's IRQ by looking at '/proc/interrupts' and lspci.

Grep output of /boot/config- for 5.4.70-rt40:

Code: Select all

root# grep -e "CONFIG_IRQ_FORCED_THREADING=y" -e "CONFIG_PREEMPT_RT=y" /boot/config-`uname -r`
CONFIG_IRQ_FORCED_THREADING=y
CONFIG_PREEMPT_RT=y
root#

This seems to be good, so far.
The complain about CPU Governors should not affect anything, since I disabled all the Run in quiet mode stuff in main board's BIOS.
So, all 12 CPU threads running between 3000 and 4000 Mhz.

[taersh]

After some days working with Kernel 5.4.70-rt40 almost all Xruns seems to be gone.
Only 1 Xrun after loading the project.
A few more when loading a project using Windows VST plugins.
No Xruns at work etc.

Screenshot.jpg (10.24 KiB) Viewed 410 times

[taersh]

Hi.

After refining some of my settings for real time audio configuration I don't have any Xruns anymore.
Zero Xruns after loading a project and working on it (no Windows VST plugins used).
And also zero Xruns after loading a project and working on it (with Windows VST plugins used).

See Screenshots:

Screenshot.jpg (109.48 KiB) Viewed 404 times

Screenshot(1).jpg (22.68 KiB) Viewed 404 times

[rockedge]

@taersh That is excellent news! I know you have been working long and hard on getting rid of those Xruns. For the 5.4.70-rt40 kernel I applied each RT patch individually after applying the AUFS5 patches to the original source using the kernel-kit.

All the latest attempts to build 5.13.X RT kernels with kernel-kit (testing branch) have ended with a compilation error that is occurring right at the end of the build process. All the patches for full RT and AUFS5 seem to be applied successfully, yet the final compilation is stopping shortly before finishing. One version did finish building but boots into a kernel panic so far.

But all reports indicate 5.4.70-rt40 is performing very well and it is a an LTS kernel.

[taersh]

Yes, it's still performing well.

Even though, if I have loaded a lot of Windows VST plugins I get Xruns only after the project is completely loaded.
But this is equal to Cubase under XP which has already some dropouts (I think this is the Windows equivalent for Xruns) when loading a project using 8 VST instruments only.
My Qtractor templates have 126+ tracks with lots of different synthesizers and plugins loaded and activated.
Working on the project, playing, recording etc. still remains very well.

Thanks for the wonderful Kernel.