Results of latency test, list of computers tested for use with LinuxCNC

degreaser wrote: Optiplex 980MT. At this point I'm chasing nanoseconds. This used a non-standard kernel, specifically the rt kernel from xanmod.org/ . The standard kernels are giving good but not quite as good results so far.

Also, I applied the irq remapping to cpu0 per this post: forum.linuxcnc.org/18-computer/25927-red...lticore-pc-s-success

That change cut the latencies in half.

Code:

LinuxCNC pc tests, version 20200930, started 06.06.2021 16:56:40 ******************************************************************************** General info: Dell Inc., OptiPlex 980 Bios version A18, dated 02/27/2018 Chipset: Intel Corporation 5 Series/3400 Series Harddisk is non-rotational, ie. SSD The amount of swap currently used is 0 ================================================================================ CPU related data: model name : Intel(R) Core(TM) i5 CPU 650 @ 3.20GHz cpu cores : 2 stepping : 5 cache size : 4096 KB ================================================================================ RAM related data: Maximum Capacity: 16 GB Size: 4096 MB Size: 4096 MB Size: No Module Installed Size: No Module Installed ================================================================================ GPU related data: product: Core Processor Integrated Graphics Controller configuration: driver=i915 latency=0 ================================================================================ Parallel port related data: number of parallel ports is 1 parport0: PC-style at 0x378 (0x778), irq 7, using FIFO [PCSPP,TRISTATE,COMPAT,EPP,ECP] ================================================================================ Os and desktop related data: PRETTY_NAME="Debian GNU/Linux 10 (buster)" Should the info below not match with your machine, kindly post the output of pstree here, including a brief desciption of your desktop environment, window manager and display manager. Tia https://forum.linuxcnc.org/18-computer/39370-script-for-automated-testing-of-computer-l atency Desktop environment : Windowmanager : e16 Displaymanager : lightdm ================================================================================ Kernel related data: Kernel 5.10.41-rt42-xanmod1 GRUB_CMDLINE_LINUX_DEFAULT="quiet isolcpus=1 mitigations=off intel_idle.max_cstate=0 pr ocessor.max_cstate=0 idle=poll acpi_irq_nobalance noirqbalance" Cpu idle driver: none ================================================================================ Kernel modules data: Check if pcspkr is loaded: Yes, may cause bigger latency. can be eliminated using: sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf Check if snd modules are loaded: Yes, may cause bigger latency. can probably be disabled in bios, alternatively, you can run "./block-snd-modules" which has just now been created for your convenience. ================================================================================ Keyboard & Mouse related data: Number of mice: 3 Mouse 0 : Logitech USB Optical Mouse Mouse 1 : CHESEN PS2 to USB Converter Mouse Mouse 2 : CHESEN PS2 to USB Converter Mouse Mice attached to USB: Logitech, Inc. M105 Optical Mouse Chesen Electronics Corp. PS/2 Keyboard+Mouse Adapter Keyboards attached to USB: Chesen Electronics Corp. PS/2 Keyboard+Mouse Adapter ================================================================================ LinuxCNC related data: LinuxCNC version is: 2.8.1 ================================================================================ Preparing for latency test: Started glxgears No. 1, 2, 3, 4, 5 .......... Started firefox with 'https://vimeo.com/150574260', WID 14680112 ================================================================================ Command for latency test is: su cadusr -c "latency-histogram --bbinsize 1000 --base 100000 --sbinsize 1000 --nox 2> &1 | tee -a 1623023787.lat &" Latency testing loop started Sun 06 Jun 2021 04:56:54 PM PDT, should end after Sun 06 Jun 2021 06:56:54 PM PDT ================================================================================ Swap useage: prerun: 0, running: 0 ================================================================================ CPU core temperatures: Core 0: Tmin: 37.0°C, Tmax: 41.0°C, (high = +89.0°C, crit = +105.0°C) Core 2: Tmin: 39.0°C, Tmax: 42.0°C, (high = +89.0°C, crit = +105.0°C) ================================================================================ last latency data is as follows:. 7202 secs base min: -9.400 uS max: 9.300 uS sdev: 0.300 uS 7202 secs servo min: -6.900 uS max: 6.900 uS sdev: 0.400 uS