System optimizations?

[moodenigo]

These are system level modifications, you can break your install, and ymmv on any perceived improvements, etc.

http://archimago.blogspot.com/2017/01/me...b.html?m=1

The mpd settings below may be of interest too, I haven’t tried the other settings but I wouldn’t underclock things that much and don’t know what the various ram settings not included in the archimago post above do.

http://www.diyaudio.com/forums/pc-based/...ost5398891

The only tweaks I have applied are the following:

- added in /boot/cmdline.txt: isolcpus=2,3
- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

I did not change anything else. This made some difference!  In fact, because of the fact that mpd and its subprocesses run on two reserved cores, and nothing else runs on those cores, you should get all the advantages of LL and RT kernels.

  Roberto

[TheOldPresbyope]

These are system level modifications, you can break your install, and ymmv on any perceived improvements, etc.

http://archimago.blogspot.com/2017/01/me...b.html?m=1

The mpd settings below may be of interest too, I haven’t tried the other settings but I wouldn’t underclock things that much and don’t know what the various ram settings not included in the archimago post above do.

http://www.diyaudio.com/forums/pc-based/...ost5398891

The only tweaks I have applied are the following:

- added in /boot/cmdline.txt: isolcpus=2,3
- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

I did not change anything else. This made some difference!  In fact, because of the fact that mpd and its subprocesses run on two reserved cores, and nothing else runs on those cores, you should get all the advantages of LL and RT kernels.

  Roberto

Hi, Roberto


What difference did you hear?

Regards,
Kent

PS - running userspace processes on isolated cores is probably more like running with a low-latency kernel than a so-called real-time kernel, but it's definitely worthwhile for latency-sensitive tasks.

[moodenigo]

The only tweaks I have applied are the following:

- added in /boot/cmdline.txt: isolcpus=2,3
- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

[color=#000000][color=#000000][color=#000000][color=#000000]I did [size=small]not change anything else. This made some difference!

Hi, Roberto

What difference did you hear?

Regards,
Kent

PS - running userspace processes on isolated cores is probably more like running with a low-latency kernel than a so-called real-time kernel, but it's definitely worthwhile for latency-sensitive tasks.

Differences: subtle, but clear improvement in imaging, and perhaps some clarity (you know, when audiophiles say "like a veil being removed" which means all and nothing). I suppose the better timing did something then. Thanks for the low-latency remark.

Roberto

[barryso]

A couple of observations.  Take them for what they are worth.

I added the CRAAP settings to /boot/config.txt and then listened for a bit.  Then added the following:

- added in /boot/cmdline.txt: isolcpus=2,3
- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF


There are definitely sonic changes that happen with these updated settings.  It sounds like the imaging is a bit better and there was a bit of midrange to high frequency grunge that went away.  Things seem more three dimensional.

It'll take a while to listen and decide if these changes are better or just different but it's worth trying if you feel comfortable editing Linux config files.  Just copy off the original files so you can go back to the original settings if this isn't to your liking.

Nice tweaks.

Thanks.

[Bento]

These are system level modifications, you can break your install, and ymmv on any perceived improvements, etc.

http://archimago.blogspot.com/2017/01/me...b.html?m=1

The mpd settings below may be of interest too, I haven’t tried the other settings but I wouldn’t underclock things that much and don’t know what the various ram settings not included in the archimago post above do.

http://www.diyaudio.com/forums/pc-based/...ost5398891

The only tweaks I have applied are the following:

- added in /boot/cmdline.txt: isolcpus=2,3
- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

I did not change anything else. This made some difference!  In fact, because of the fact that mpd and its subprocesses run on two reserved cores, and nothing else runs on those cores, you should get all the advantages of LL and RT kernels.

  Roberto

Hi Roberto, how did you go about editing:

- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

Could you help a dummy like me?

[hifix]

I've had a look and cannot find:
/boot
/lib
etc.

This is the directory for a 3.81 install.
Are the tweaks for V4 and beyond ?

[JST1963]

Hi moOde fans,

[hifix]

I've had a look and cannot find:
/boot
/lib
etc.

This is the directory for a 3.81 install.
Are the tweaks for V4 and beyond ?

This is what you see when you put the µSD card into a card reader and into your computer.
But that won't show you the complete directory structure.
In fact you need to log in with SSH and there you'll find the boot folder, the lib folder and many many more...

Johan

Thanks Johan!
I'll be giving it another go.

[moodenigo]

I logged into the raspberry pi running mode (with SSH from my comouter) and used the little editor called "pico" from the terminal.

To change system files you have to use "sudo pico" where "sudo" means "super-user do" in other words editing can only be done as an entity working with privileges similar to root. 

Probably you can edit directly the files from your computer if you have some drivers installed that support the ext file systems. I can do it on my Mac, but it required additional commercial software installed. Or from a linux computer.

 Roberto

These are system level modifications, you can break your install, and ymmv on any perceived improvements, etc.

http://archimago.blogspot.com/2017/01/me...b.html?m=1

The mpd settings below may be of interest too, I haven’t tried the other settings but I wouldn’t underclock things that much and don’t know what the various ram settings not included in the archimago post above do. 

http://www.diyaudio.com/forums/pc-based/...ost5398891

The only tweaks I have applied are the following:

- added in /boot/cmdline.txt: isolcpus=2,3
- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

I did not change anything else. This made some difference!  In fact, because of the fact that mpd and its subprocesses run on two reserved cores, and nothing else runs on those cores, you should get all the advantages of LL and RT kernels.

  Roberto

Hi Roberto, how did you go about editing:

- changed options in /lib/systemd/system/mpd.service
    CPUSchedulingPolicy=fifo
    CPUSchedulingPriority=70
    Nice=-15
    ExecStart=/usr/bin/taskset -c 2,3 /usr/local/bin/mpd --no-daemon $MPDCONF

Could you help a dummy like me?

[kvik2]

^ As mentioned above..

Open Terminal
ssh pi@IP-address (password: moodeaudio)
sudo pico /lib/systemd/system/mpd.service

Use arrows to move around. Change values. Ctrl + X to exit.