7 Jun
2020
7 Jun
'20
3:39 p.m.
Den sön 7 juni 2020 kl 13:22 skrev rosea.grammostola <
rosea.grammostola(a)gmail.com>gt;:
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.
Hey I got one of those, very good laptop :)
At least I can run Zynaddsubfx with 0.726 msec latency now without xruns
using a cheap Behringer usb device. ;)
Do you mind sharing a bit more what settings and toolchain this includes?
kernel? distro? Jack? what buffersettings?
--
On a related note, I tested some more with the standard xanmod-rt-edge
kernel on another laptop (hp something, the troubled one I mentioned
earlier) under kubuntu 20.04 and it does seem this kernel behaves a bit
better than the lowlatency kernel I had before. It is not a night and day
difference.
Also, not sure if this is general knowledge, but I've had the feeling
before that disabling graphical login and running X with startx improves
resiliency to xruns, tried it now again and I believe it is still true.
I've got no metrics apart from counting xruns when doing some startup
operations of my rig with 128 frame buffers.
/Robert
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