[OT] But the Megabot, giant robot guys (""Make"" magazine vol 58) are
running rtai. Don't know what for.
----- Original Message -----
From: "sam sokolik" <sa...@empirescreen.com>
To: <emc-users@lists.sourceforge.net>
Sent: Wednesday, July 12, 2017 11:13 AM
Subject: Re: [Emc-users] Maybe we don't need rtai anymore?
here is a shot of linuxcnc running a 30us base period. You can see the
jitter on this analog scope.
http://electronicsam.com/images/matsuura/20170712_130107.jpg
Using parport resest (5us). So theoretically you could run close to
30khz with rt_preempt on this system (3rd gen i5).
sam
(scope isn't calibrated very good)
On 7/4/2017 10:15 PM, Jon Elson wrote:
On 07/04/2017 05:22 PM, sam sokolik wrote:
Well - I have been playing with debian stretch and 4.9.0-3-rt kernel.
I booted our matsuura (j1900 quad core) which with no tweeking has aprox
100us latency. (it has been running mesa ethernet cards with
rt_preempt - no issues) Next I booted it with some kernel line tweaks.
(checking the hardware - processors 0,1 and 2,3 share cache. So I added
isolcpus=2,3 idle=poll
The latency on this system was phenomenal. It has been running for
hours now and still <6us
6 us is quite good, although RTAI can do better on some boxes. But, 6 us
is probably good for most interfaces.
Jon
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