Hi,
I guess the nice values are null and void, IOW IIUC they don't affect
anything [1], at least for cosmetical reasons remove it from your
limits.conf. If you fear that something could become unresponsive, you
could decrease "rtprio 99" to a lower value. I never did it myself, but
some users do so.
To optimize real-time performance you should start with using Rui's
script rtirq [2]. There are other things to improve real-time
capability, often setting the cpu frequency scaling governor to
performance improves a lot [3]. There are additional useful
opportunities, e.g. unbinding USB devices that share an IRQ with the
audio device could be helpful, but a lot of hints provided by the
Internet are plain nonsense. The most important thing to consider is
choosing the appropriate kernel. For some tasks it's useful to build a
rt patched kernel [4]. The so called "lowlatency" kernels provided by
Ubuntu flavours gains you more or less nothing. If you should use a
mainline kernel, simply add "threadirqs" to the boot parameters, for
syslinux it does look like e.g. this
$ grep thread /boot/syslinux/syslinux.cfg -B1 -A1
LABEL Threadirqs
MENU LABEL Arch Linux ^threadirqs
LINUX ../vmlinuz-linux
APPEND root=LABEL=archlinux ro threadirqs
INITRD ../initramfs-linux.img
I prefer using real-time patched kernels. If you should use external
MIDI equipment there are other things to consider, too, special jackd
settings, e.g. for jack 2 the "-X alsarawmidi" switch and that using USB
MIDI much likely does cause much more MIDI jitter compared to game port
MIDI and PCI/PCIe MIDI.
Regards,
Ralf
[1]
"Contrary to a lot of misinformation on the web, there is no reason to
include a line here that provides enhanced “niceness” control, which is
completely irrelevant for realtime scheduling and low latency audio
applications." - http://jackaudio.org/faq/linux_rt_config.html
[2]
http://www.rncbc.org/jack/
[3]
echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor >/dev/null
To see the status run
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
to get back "powersave" or "ondemand" run
echo powersave | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor >/dev/null
^^^^^^^^^
resp. replace "powersave" with "ondemand"
[4]
https://www.kernel.org/pub/linux/kernel/projects/rt/
_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@xxxxxxxxxxxxxxxxxxxx
https://lists.linuxaudio.org/listinfo/linux-audio-user
