On 6/4/20 3:09 PM, Paul Davis wrote:
This is wrong. The behavior of a "normal", "low latency" and
"preempt-RT" kernel are all different, and for realtime audio work,
the correct behavior is only going to happen with a "preempt-RT" kernel.
However ...
The behavior of the normal and "low latency" kernels have changed over
the years too, and on *some* systems (from a hardware perspective),
they will function similarly enough to a "preempt-RT" kernel that a
realtime audio workflow will be just fine. In addition, the "behavior"
gap between a "preempt-RT" kernel and a normal kernel will be less and
less apparent as the latency settings (buffer/period size) become more
relaxed (i.e. grow larger).
How do you know which systems this is true for? You just have to try
it. It is a complicated mixture of many different aspects of the
hardware. There's an overview of the kinds of things that can
contribute to the need for a "preempt-RT" kernel here:
https://manual.ardour.org/setting-up-your-system/the-right-computer-system-…
Useful information.
Fwiw, I did my best to optimize a thinkpad t420 laptop for linuxaudio
using the realtime script from the wiki mostly and the information in
the Ardour docs.
At least I can run Zynaddsubfx with 0.726 msec latency now without xruns
using a cheap Behringer usb device. ;)