Have checked the sockets options: timeout.tv_sec = 0; timeout.tv_usec = 1; r = setsockopt(*psock, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)); r = setsockopt(*psock, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout)); So should not block for several thousand µs.
Kernel version: SMP PREEMPT_RT Debian 6.12.107-1 (2026-08-29) So maybe there is hope version 7.x will solve problem? Will try to get hardware timestamp on Ethernet frames to get timestamps I fully trust. 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
