Re: [LAU] limits.conf nice rtprio

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/