Mesa card vs. Video card?

I have an Atom D525 box. I have read on here that the Mesa cards give you lower better latency. I have also experienced lowering my screen resolution improves latency--when I dropped it to 640x480, there was a jump in performance, from 8700 to 6500. (Disclaimer: short tests, only 2-3 minutes long, so these are not heavy stress tests--but they were repeatable.)

Does anybody have an idea about which would give the best performance boost, an add-on video card, or a Mesa card? I really want to bring my resolution back up to 1280-960, and would like to do it with the "best" latency performance boost at the same time.

Thanks...

A Mesa card (or other add on LinucCNC hardware like PicoSystems USC)
will have little if any effect on your latency.

Hardware step generators however will generate much higher (and smoother)
step rates than LinuxCNCs software step generator can, and are much less affected
by the host CPU latency.

This is because the actual step generation is done in hardware
(basically by a programmable digital oscillator)

I have also experienced lowering my screen resolution improves latency--when I dropped it to 640x480, there was a jump in performance, from 8700 to 6500.

8700 is a very good latency figure, don't bother making the system unusable just to try and get a lower figure.

My D525 does resolutions up to 1920x1080 using the on board video chip without any problems ( I use it mainly as a media streamer but have tested latency ).

The main things to do with a D525 to improve latency, are to use the isolcpus=1 kernel parameter, disable all power management and multi-threading.

www.linuxcnc.org/index.php/english/forum...-the-latency-problem
www.linuxcnc.org/index.php/english/forum...me-latency-solutions
wiki.linuxcnc.org/cgi-bin/wiki.pl?Troubl...lcpus_Boot_parameter

Note that unless you tune your system to take the best advantage of the lowest base-thread figure that you can reliably run, latency figures are a bit academic because you will not see the full benefits.

wiki.linuxcnc.org/cgi-bin/wiki.pl?Tweaki...ftwareStepGeneration

regards

PCW wrote:

Hardware step generators however will generate much higher (and smoother)
step rates than LinuxCNCs software step generator can, and are much less affected
by the host CPU latency.

This is because the actual step generation is done in hardware
(basically by a programmable digital oscillator)

Is there a list of these that work with LinuxCNC? (Or can you recommend one?)

Thanks.

tenaja wrote:

PCW wrote:

Hardware step generators however will generate much higher (and smoother)
step rates than LinuxCNCs software step generator can, and are much less affected
by the host CPU latency.

This is because the actual step generation is done in hardware
(basically by a programmable digital oscillator)

Is there a list of these that work with LinuxCNC? (Or can you recommend one?)

Thanks.

There is also the Pico Systems Universal Stepper Controller, a more "all in one"
solution. Works pretty much identically to the Mesa boards, fully supported by
LinuxCNC. See
<pico-systems.com/osc2.5/catalog/product_...ath=4&products_id=30>
for more info.

Jon