I open this post again, as I finally found why I got the message " systemd-udevd: failed to execute '/bin/systemctl' '/bin/systemctl start --no-block nvidia-persistenced.service': No such file or directory " at startup, and cleared the dmesg log.
First of all, if you are still using upstart as me, but with the systemd-shim package, to emulate the systemd structure for some reason, the message is caused by an unnecessary configuration file from Nvidia package (yes, unfortunately, at today, you have to do all this procedure, every time you upgrade the nvidia drivers).
Before proceding, check if you are correctly running the nvidia-persistenced from upstart call.
Run the command nvidia-smi from the shell, you must see somewhere on the left top "Persistence-M On".
If it's "off", even if is safe to run nvidia drivers without it on (I did for many months wiothout any glitch) best before proceding, to go to read nvidia-persistenced manuals and manage to have it started from upstart (I am sorry but I forgot the exact operations, still, I managed reading this official manual http://docs.nvidia.com/deploy/driver-pe ... stallation
and this topic https://devtalk.nvidia.com/default/topi ... sistenced/
Then, we are at the 'grand finale'!
Go to /lib/systemd/system/ . Here you will find a file called nvidia-persistenced.service.
Simply delete it with root privileges (best before, you move it somewhere, to test if it's going smoothly as for me!
Go to /lib/udev/rules.d/
Open as root the config file 71-nvidia.rules
Comment as posted here below the lines:
# Start and stop nvidia-persistenced on power on and power off
#ACTION=="add" DEVPATH=="/bus/acpi/drivers/NVIDIA ACPI Video Driver" SUBSYSTEM=="drivers" RUN+="/bin/systemctl start --no-block nvidia-persistenced.service"
#ACTION=="remove" DEVPATH=="/bus/acpi/drivers/NVIDIA ACPI Video Driver" SUBSYSTEM=="drivers" RUN+="/bin/systemctl stop --no-block nvidia-persistenced"
# Start and stop nvidia-persistenced when loading and unloading
# the driver
#ACTION=="add" DEVPATH=="/module/nvidia" SUBSYSTEM=="module" RUN+="/bin/systemctl start --no-block nvidia-persistenced.service"
#ACTION=="remove" DEVPATH=="/module/nvidia" SUBSYSTEM=="module" RUN+="/bin/systemctl stop --no-block nvidia-persistenced"
Now you can restart and check dmesg log file.
Tadaa!!! No more annoying message about.
Hope to be helpfull.