Kernel Optimizations and Rpi 2

Frost_dk

Hello.
First, Thanks for a very useful music player. It is the best i have tried yet on my Rpi. I have great experience with the diffrent kernel optimizations on my Rpi. I really love Orion (More spacious, with a lot of Room information), Orion V2 (very "Tight", a bit over damped for my room,but great in rooms with more lively acoustics), and Uggunau ( On my setup, it is a good compromise between orion and V2)
BUT i have a question.. how come it is that i Cant tell any difference between the sound signatures when im using a Rpi2? On my "normal" rpi, it is quite easy to tell the difference, but with the Rpi 2, the signatures does not make any difference at all. Am i the only one that can't get it to work properly, or can you help me get the optimizations to work on Rpi 2.

Thanks, in advance

Kind Regards,
Rune Frost, Denmark

hondagx35

Hi Frost_dk,

how come it is that i Cant tell any difference between the sound signatures when im using a Rpi2?

This is because the file is not adapted / modified for use with RP2.

Frank

dynobot

hondagx35 wroteHi Frost_dk,

how come it is that i Cant tell any difference between the sound signatures when im using a Rpi2?
This is because the file is not adapted / modified for use with RP2.

Frank

Huh?

These are kernel level tweaks that change no matter what hardware its being used on....

If anything I can see that the 'file' is pretty much non-functional in v0.3.

Either way I think my tweaks sound best, esp when I use cpu affinity for mpd.

Frost_dk

Wow.. that was a fast response

, Thank you very much for your reply.
unfortunately, Im not experienced enough to alter the files myself, and i must assume that the set of optimizations needed is diffrent from the original Rpi, since the changes is not already made?

Thank you for your huge effort in getting RuneAudio even better

Frost_dk

dynobot wrote
hondagx35 wroteHi Frost_dk,

how come it is that i Cant tell any difference between the sound signatures when im using a Rpi2?
This is because the file is not adapted / modified for use with RP2.

Frank

Huh?

These are kernel level tweaks that change no matter what hardware its being used on....

If anything I can see that the 'file' is pretty much non-functional in v0.3.

Either way I think my tweaks sound best, esp when I use cpu affinity for mpd.

Actually i can hear quite a difference when using my Rpi 1 with current 0.3 Beta.
Is there somewhere i can read about the optimizations you have done?

kind regards

dynobot

Frost_dk wrote Actually i can hear quite a difference when using my Rpi 1 with current 0.3 Beta.
Is there somewhere i can read about the optimizations you have done?

kind regards

Look toward the bottom of the page

https://sites.google.com/site/computeraudioorg/home/micro-computers-and-laptops

Frost_dk

Thank you very much for the link.
I will enjoy reading it

Kind regards,
Rune Frost

Frost_dk

hondagx35 wroteHi Frost_dk,

how come it is that i Cant tell any difference between the sound signatures when im using a Rpi2?
This is because the file is not adapted / modified for use with RP2.

Frank

Hi Frank.
How can i tell which hardware ID an Rpi2 has? Is it 08?
Can i "just" copy the rpi1 section is orion_optimize and change hardware id? I would really like to have the possibility to change between optimizations. I am aware that the optimizations made to the Rpi1 kernel timings, will not necessary be an improvement on the Rpi2, as it is diffrent hardware.
Thanks in advance.
Kind regards,
Rune Frost

hondagx35

Hi Frost_dk,

How can i tell which hardware ID an Rpi2 has? Is it 08?

Yes it is 08 see here.

Can i "just" copy the rpi1 section is orion_optimize and change hardware id?

Yes you can, but leave out the nrpacks section.
The option nrpck is not available anymore with newer kernel versions.
You can check this with:

modinfo snd-usb-audio | grep ^parm:

I am aware that the optimizations made to the Rpi1 kernel timings, will not necessary be an improvement on the Rpi2, as it is diffrent hardware.

This and because the lack in time is the reason why it is not implemented yet.

Try it like this:

    # Cubietruck
    if ((${hw} == "06")) 
    then
        echo ${s06} > /proc/sys/kernel/sched_latency_ns
        echo "sched_latency_ns = "${s06}
        sndusb_profile nrpacks=${u06}
        echo "USB nrpacks="${u06}
    fi
    # RaspberryPi2/3
    if ((${hw} == "08")) 
    then
        echo ${s08} > /proc/sys/kernel/sched_latency_ns
        echo "sched_latency_ns = "${s08}
        #sndusb_profile nrpacks=${u06}     not supported anymore
        #echo "USB nrpacks="${u06}
    fi
}

OK, i updated the dev branch.
Please try

cd /var/www
git pull

Please report your experiences.

Frank

Frost_dk

Hi again.
I have now tried your changes, and im not sure that i can hear a difference, perhaps a very small one, not like the difference on the rpi1.
I have isolated core 3 to MPD only(by following your guide elsewhere in this forum), perhaps it is why there is such a small difference, if any at all.
When I switch between the kernel profiles, there is no stop in the music, and no blue GUI mentioning the changes. On my Rpi1 there is a blue box showing the changes, and there is a small stop in the music. Perhaps that is why i dont think the changes are applied.
BUT when I look at the MTU under ifconfig, there is a change between ORION and ACX (1000 vs 1500 MTU), just as described in orion_optimize.
Thank you for you help.
Kind regards,
Rune

hondagx35

Hi Frost_dk,

On my Rpi1 there is a blue box showing the changes, and there is a small stop in the music.

This is because of the missing nrpacks changes.
All other settings do not need mpd to restart.

Frank

Frost_dk

Ok.. Thanks for your reply. I really appreciate it

Ill guess that it is working now then, but but the changes in sound quality is very subtle.
One last question.. Can you point me to some information about the optimizations itself, if possible? Or is it a bit too "hardcore" for at normal linux user?
Thanks

hondagx35

Hi Frost_dk,

the script changes the following:

- MPDs process priority.
This is done with the linux command nice / renice.
Because of your isolated core, this may be not noticeable.

- CIFs process priority.
If you have your music on a SMB/CIFS share this may be noticeable.

- Kernel scheduler latency.
Very complex thing, also the default schedulers have changed with kernels.

- nrpacks
nrpacks which defines how often your USB controller will throw an IRQ/how many frames the USB core will prepare in advance for the USB controller to process on its own. So it is manly for USD DACs.
This parameter has been removed by a patch which reworks the packet size calculation logic on newer kernels.

Frank

Frost_dk

hondagx35 wroteHi Frost_dk,

the script changes the following:

- MPDs process priority.
This is done with the linux command nice / renice.
Because of your isolated core, this may be not noticeable.

- CIFs process priority.
If you have your music on a SMB/CIFS share this may be noticeable.

- Kernel scheduler latency.
Very complex thing, also the default schedulers have changed with kernels.

- nrpacks
nrpacks which defines how often your USB controller will throw an IRQ/how many frames the USB core will prepare in advance for the USB controller to process on its own. So it is manly for USD DACs.
This parameter has been removed by a patch which reworks the packet size calculation logic on newer kernels.

Frank

Hi,

Again, Thank you for your patience and that you are willing to help us all.

I can see that for my setup, the thing that could have an impact is the "Kernel scheduler latency", and unfortunately i believe that it demands more knowledge than i have.
I will enjoy the runeaudio player with the current settings, i still need to compare the original Rpi1 with orion2 settings, with the rpi2 with this settings

Thank you, and have a nice day.

Rune Frost

Frost_dk

Frost_dk wrote
hondagx35 wroteHi Frost_dk,

the script changes the following:

- MPDs process priority.
This is done with the linux command nice / renice.
Because of your isolated core, this may be not noticeable.

- CIFs process priority.
If you have your music on a SMB/CIFS share this may be noticeable.

- Kernel scheduler latency.
Very complex thing, also the default schedulers have changed with kernels.

- nrpacks
nrpacks which defines how often your USB controller will throw an IRQ/how many frames the USB core will prepare in advance for the USB controller to process on its own. So it is manly for USD DACs.
This parameter has been removed by a patch which reworks the packet size calculation logic on newer kernels.

Frank

Hi,

Again, Thank you for your patience and that you are willing to help us all.

I can see that for my setup, the thing that could have an impact is the "Kernel scheduler latency", and unfortunately i believe that it demands more knowledge than i have.
I will enjoy the runeaudio player with the current settings, i still need to compare the original Rpi1 with orion2 settings, with the rpi2 with this settings
Thank you, and have a nice day.

Rune Frost

I just found this information, perhaps i can give others an idea of what the scheduler latency does .

http://ccrma.stanford.edu/planetccrma/software/understandlowlat.html

Frost_dk

Hello Again
I have now been using a Rpi3 (recognized as a Rpi2) for a while, and I think I owe you (Frank) a short update.

I CAN hear a difference when using the different kernel optimizations. It is not a HUGE difference, but clearly noticeable.
The setting OrionV2 is the most "damped" one with great transparency in the midrange. The 2 OrionV3's has more "sparkle", but has not the full transparency as the V2..

If you ever need someone to listen/test some future changes in the optimizations, then I will be more than happy to try it for you!

Kind regards,
Rune Frost