LinuxCNC S-Curve Accelerations

I really think this discussion of latency is irrelevant. I've had my doubts about 2 core CPU's being adequate for a few years but with careful tuning they work for some.

Either the latency is acceptable or it isn't on a specific PC. There is no hard and fast rule for what is acceptable.You all seem to be working with ethercat or Mesa devices so system latency is no longer relevant if the  system is correctly set up to minimize system processes that cause periodic latency spikes.

Network latency is a fairly new concept for Linuxcnc users and has only been an issue since the release of Debian Bullseye but that coincides with increased power saving technology and an insistence by kernel developers to use fully open source network drivers and not incorporate the Realtek DKMS drivers where full source is not available.

I really would like to see actual results discussed,  not theoretical dicussions about what might work and what might not. From kernel traces, I know there is a spare 800 ns on most systems before latency will be an issue. I am sure that is more than enough to support any additional processing.

O_o

o_O

The scurve is present now in linuxcnc master, download from GitHub and build, or use the latest .deb files

With many thanks to Grandixximo and 杨阳 we now have an experimental
S-curve / finite-jerk trajectory planner for testing.

For those that build from source just look for the new v2.10.0-pre1 tag.

Others can download debs from github for the next 90 days:
x86 / bookworm  github.com/LinuxCNC/linuxcnc/actions/run...artifacts/5056097663
x86 / trixie github.com/LinuxCNC/linuxcnc/actions/run...artifacts/5056161668
ARM64 / bookworm github.com/LinuxCNC/linuxcnc/actions/run...artifacts/5056139840
ARM64 / trixie github.com/LinuxCNC/linuxcnc/actions/run...artifacts/5056124080

Make no mistake, this is experimental, there are no guarantees that
these won't break your machines. The first user already hit the hard
stops when homing (too-low max jerk setting)
With the jerk setting it is probably best to start high and reduce, as
infinite jerk is closer to current behavior.

If you run these you are volunteering to be a guinea-pig.
magazine.punch.co.uk/image/I0000NOWOOdkXT_k

Just a quick test and I got large following errors:

 

ini setting are:

 

Is a jerk of 2000 reasonable? What units is your config?

Thank you Peter for looking at this.
I see a few issues with your ini.txt

16 float IN 1e+99 ini.traj_default_acceleration
16 float IN 0 ini.traj_default_jerk
16 float IN 1 ini.traj_default_velocity
16 float IN 1e+99 ini.traj_max_acceleration
16 float IN 0 ini.traj_max_jerk
16 float IN 1e+99 ini.traj_max_velocity


these settings seems a bit waky, if you want to have jerk control you need
ini.traj_default_jerk
and
ini.traj_max_jerk

to be more than 0
and the 1e+99 max acc and velocity, is this something people actually run with? is it something is supported without f-error on TP0 aka old TP?