I wonder if I'm having the same problem.
I have a MESA 7i92H on a PC. I boot, I home all axis. Maybe jog around a bit.
Then hit the ESTOP to remove power to the drives, turn off monitor and leave
the shop. The PC stays running. A day or two later I come back and everything
is fine.
Or...
I get this message as shown in the attached latency.txt file.
Unexpected realtime delay on task 0 with period 1000000
This Message will only display once per session.
Run the Latency Test and resolve before continuing.
This error may not show up for days and never really when I'm working with the
system either running G-code or doing something manually.
Suggestions?
Thanks
John
> -----Original Message-----
> From: Nicklas SB Karlsson [mailto:[email protected]]
> Sent: September 17, 2026 1:31 PM
> To: [email protected]
> Subject: Re: [Emc-users] Ethernet send packets jitter
>
> Nailed it down to recv(...) function call. Measured with 1 �s resolution this
> call usually take around 1 �s but
> sometimes it take up several thousand micro seconds. Previously measured
> these delays of several milliseconds
> seems to happen with a periodicity of 16 to 17 milliseconds corresponding
> to a frequency of around 60 Hz. Rule
> out noise from power grid since this is 50 Hz in Sweden.
>
> Have not had time to try what you suggest yet but have a lot more time
> tommorow.
>
> Anybody have any about cause of these extra delays on recv(...) ??
> Rule blocking call since data i sent in an Ethercat ring from a single thread.
> With no Ethernet frames sent it
> should either block or receive.
>
> Nicklas Karlsson
>
>
> tor 2026-09-17 klockan 07:28 -0700 skrev Peter Wallace:
> > On Thu, 17 Sep 2026, andy pugh wrote:
> >
> > > On Wed, 16 Sept 2026 at 21:20, Nicklas SB Karlsson <[email protected]>
> wrote:
> > >
> > > > Running Linuxcnc and send receive Ethernet jitter is small for most
> packets but sometimes there is delay of well
> > > > above on millisecond, running for maybe a minute or so worst case is
> between 6...7 milliseconds.
> > >
> > > Maybe you need to disable IRQ coalescing? It's mentioned briefly in
> > > the hm2_eth docs, but also might be relevant to EtherCAT.
> > > https://linuxcnc.org/docs/stable/html/man/man9/hm2_eth.9.html
> > >
> > > (It's at least a google-able phrase for further investigation)
> >
> > At least for hm2_eth, basic Network latency improvement methods are:
> >
> >
> > On Intel (and some less common others like broadcom), disable IRQ
> coalescing
> >
> > On Realtek, install the DKMS driver (the stock Linux driver has multi-ms
> > random latencies)
> >
> > On all, use isolcpus (or whatever the newer scheme is called) to isolate the
> > last CPU, and then pin the Ethernet IRQ to that CPU.
> >
> > Use the latest kernel (I have a test system that always got random
> timeouts,
> > say once a day, with 6.x kernels, this was totally fixed with a 7.X kernel
> >
> >
> > >
> > > --
> > > atp
> > > "A motorcycle is a bicycle with a pandemonium attachment and is
> > > designed for the especial use of mechanical geniuses, daredevils and
> > > lunatics."
> > > ? George Fitch, Atlanta Constitution Newspaper, 1912
> > >
> > >
> > > _______________________________________________
> > > Emc-users mailing list
> > > [email protected]
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> > Peter Wallace
> > Mesa Electronics
> >
> >
> > _______________________________________________
> > Emc-users mailing list
> > [email protected]
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
> _______________________________________________
> Emc-users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/emc-users
LINUXCNC - 2.8.1
Machine configuration directory is '/home/john/linuxcnc/configs/G3616-MESA-7i92'
Machine configuration file is 'G3616-MESA-7i92.ini.expanded'
Starting LinuxCNC...
Found file(REL): ./G3616-MESA-7i92.hal
Note: Using POSIX realtime
hm2: loading Mesa HostMot2 driver version 0.15
hm2_eth: loading Mesa AnyIO HostMot2 ethernet driver version 0.2
hm2_eth: 192.168.1.121: INFO: Hardware address (MAC): 00:60:1b:12:06:0f
hm2_eth: discovered 7I92
hm2/hm2_7i92.0: Low Level init 0.15
hm2/hm2_7i92.0: 34 I/O Pins used:
hm2/hm2_7i92.0: IO Pin 000 (P2-01): IOPort
hm2/hm2_7i92.0: IO Pin 001 (P2-14): StepGen #5, pin Step (Output)
hm2/hm2_7i92.0: IO Pin 002 (P2-02): StepGen #0, pin Step (Output)
hm2/hm2_7i92.0: IO Pin 003 (P2-15): IOPort
hm2/hm2_7i92.0: IO Pin 004 (P2-03): StepGen #0, pin Direction (Output)
hm2/hm2_7i92.0: IO Pin 005 (P2-16): StepGen #5, pin Direction (Output)
hm2/hm2_7i92.0: IO Pin 006 (P2-04): StepGen #1, pin Step (Output)
hm2/hm2_7i92.0: IO Pin 007 (P2-17): StepGen #4, pin Step (Output)
hm2/hm2_7i92.0: IO Pin 008 (P2-05): StepGen #1, pin Direction (Output)
hm2/hm2_7i92.0: IO Pin 009 (P2-06): StepGen #2, pin Step (Output)
hm2/hm2_7i92.0: IO Pin 010 (P2-07): StepGen #2, pin Direction (Output)
hm2/hm2_7i92.0: IO Pin 011 (P2-08): StepGen #3, pin Step (Output)
hm2/hm2_7i92.0: IO Pin 012 (P2-09): StepGen #3, pin Direction (Output)
hm2/hm2_7i92.0: IO Pin 013 (P2-10): IOPort
hm2/hm2_7i92.0: IO Pin 014 (P2-11): Encoder #0, pin A (Input)
hm2/hm2_7i92.0: IO Pin 015 (P2-12): Encoder #0, pin B (Input)
hm2/hm2_7i92.0: IO Pin 016 (P2-13): Encoder #0, pin Index (Input)
hm2/hm2_7i92.0: IO Pin 017 (P1-01): IOPort
hm2/hm2_7i92.0: IO Pin 018 (P1-14): IOPort
hm2/hm2_7i92.0: IO Pin 019 (P1-02): PWMGen #0, pin Out0 (PWM or Up) (Output)
hm2/hm2_7i92.0: IO Pin 020 (P1-15): IOPort
hm2/hm2_7i92.0: IO Pin 021 (P1-03): IOPort
hm2/hm2_7i92.0: IO Pin 022 (P1-16): IOPort
hm2/hm2_7i92.0: IO Pin 023 (P1-04): IOPort
hm2/hm2_7i92.0: IO Pin 024 (P1-17): IOPort
hm2/hm2_7i92.0: IO Pin 025 (P1-05): IOPort
hm2/hm2_7i92.0: IO Pin 026 (P1-06): IOPort
hm2/hm2_7i92.0: IO Pin 027 (P1-07): IOPort
hm2/hm2_7i92.0: IO Pin 028 (P1-08): IOPort
hm2/hm2_7i92.0: IO Pin 029 (P1-09): IOPort
hm2/hm2_7i92.0: IO Pin 030 (P1-10): IOPort
hm2/hm2_7i92.0: IO Pin 031 (P1-11): Encoder #1, pin A (Input)
hm2/hm2_7i92.0: IO Pin 032 (P1-12): Encoder #1, pin B (Input)
hm2/hm2_7i92.0: IO Pin 033 (P1-13): Encoder #1, pin Index (Input)
hm2/hm2_7i92.0: registered
Found file(REL): ./custom.hal
Found file(LIB): /usr/share/linuxcnc/hallib/xhc-hb04.tcl
xhc-hb04: waiting for XHC-HB04 device
xhc-hb04: found XHC-HB04 device
xhc-hb04.tcl: using std_start_pause_button
xhc-hb04.tcl: Using existing outpin signame: spindle-vel-cmd-rps-abs
APP: xset found: </usr/bin/xset>
note: MAXV max: 3.000 units/sec 180.000 units/min
note: LJOG max: 3.000 units/sec 180.000 units/min
note: LJOG default: 1.000 units/sec 60.000 units/min
note: AJOG max: 180.000 units/sec 10800.000 units/min
note: AJOG default: 90.000 units/sec 5400.000 units/min
note: jog_order='XYZA'
note: jog_invert=set([])
Original coordinate system is 1.000000 identified as 540.000000
Workspace_Z is -8.764000
Old Tool 0.000000 New tool 0.000000
No Tool Selected so remove offset
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
**** PROBE SCREEN INFO ****
**** To many increments given in INI File for this screen ****
**** Only the first 5 will be reachable through this screen ****
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
**** probe_screen GETINIINFO ****
Preference file path:
/home/john/linuxcnc/configs/G3616-MESA-7i92/G3616-MESA-7i92.pref
48234499
('tool-number =', 0)
('tool_prep_number =', 0, False)
Combi DRO all homed
Combi DRO all homed
Combi DRO all homed
Combi DRO all homed
Combi DRO all homed
Combi DRO all homed
task: main loop took 0.103014 seconds
task: main loop took 0.114556 seconds
task: main loop took 0.100912 seconds
task: main loop took 0.121040 seconds
task: main loop took 0.100500 seconds
task: main loop took 0.120169 seconds
task: main loop took 0.100095 seconds
Unexpected realtime delay on task 0 with period 1000000
This Message will only display once per session.
Run the Latency Test and resolve before continuing.
Unexpected realtime delay on task 0 with period 1000000
This Message will only display once per session.
Run the Latency Test and resolve before continuing.
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