> On 25 Apr 2019, at 09:59, "[email protected]" <[email protected]> wrote: > > >> On 24/04/19 20:57, mngr wrote: >> Hi, >> >> I am trying to improve the latency on my Machinekit installation. >> As hardware I have an ASRock 90-MXB870-A0UAYZ. I have chosen this because I >> read about it in the linuxcnc forum. >> >> I am using Debian 9.8, with kernel 4.9 rt >> >> machinekit@debian:~$ uname -a >> Linux debian 4.9.0-8-rt-amd64 #1 SMP PREEMPT RT Debian 4.9.144-3.1 >> (2019-02-19) x86_64 GNU/Linux >> >> >> >> The latency I have is 50 microsecond, and from what I have read it is a bit >> too high (it should be between 10 and 30 microsecond) >> so I started studying about latency in the rt kernel. > A search of their site failed to find any ref to this MB, it is not in their > latency-test list. Do you have a link? > > All their testing will have been with rtai kernels (and then exaggerated very > often). > > What is your aim, to do software stepgen and use a PCI parport board? > > You will need to look at isolcpus, acpi_irq_nobalance, noirqbalance etc. > Turn off hyper threading, virtualisation, suspend to RAM, most of power > management. > > If that does not get you where you want to be, we have added support for > libcgroup, partrt etc which has been tested on Intel processors to bring > latency down dramatically. > John Morris did a page in the docs here > http://www.machinekit.io/docs/hal/threads-and-latency/
I have a setup using a J1900, isolated CPU’s 2 and 3 (they share the L2 cache) and the cgroups setup. The max latency I got, running 5 glxgears and a simple thread on those isolated CPU’s was approx 9000 ns. (I had it running for 48 hrs). No other special tweaks done. > In theory this could be used with rt-preempt kernels for software stepgen. > You need to read it carefully because the number of cores and how the L2 > cache is organised are critical, don't know how AMD do it, > haven't used one for yonks. > > regards > -- > website: http://www.machinekit.io blog: http://blog.machinekit.io github: > https://github.com/machinekit > --- > You received this message because you are subscribed to the Google Groups > "Machinekit" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > Visit this group at https://groups.google.com/group/machinekit. > For more options, visit https://groups.google.com/d/optout. -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
