Strange Latency

Hello...

I'm tested computer if it's good candidate for LinuxCNC.
For now I do half hour test with LiveCD Ubuntu 8.04 and 10.04.
I didn't change anithyng in setup. Just Run live CD and start latency test and then run glxgears and do some browsing in web.
And I got latency 11200 with Ubuntu 8.04 and 33150 with Ubuntu 10.04 (base thread, servo thread is close of this valves)

I don't understand why that big difference? As this is new machine to go I prefer 10.04 as 8.04 is pretty old now and who know when they reach out of life.
But latency with 10.04 is horrible. (maybe stil usable as mesa card will serve stepgen. )

Hi

You don't say what the computer is, but these FAQS should cover the reasons

www.linuxcnc.org/index.php/english/forum...-the-latency-problem
www.linuxcnc.org/index.php/english/forum...me-latency-solutions

What you describe is very common, very few older single core machines run better with 10.04 than 8.04

regards

Hello..
I do Longer test (Overnight + few hour) on both system and got closer latency. On 8.04 is still better for 5us, and on 10.04 I got 33000 range in few seconds and then stay there.
Onboard is Pentium D processor running at 3GHz.
As that lattency figure isn't bad for hardware stepgen (mesa 7i43) I just kept 10.04 as that have few whistles I like.

Hopefuly will drive large gantry 5 axis machine.