Steve,

That seemed to have worked pretty well, at least for latency test. Servo
thread jitter went from 6484 to 4790, and base thread jitter went from 7148
to 3562. The odd thing is, when I start EMC I am still getting "unexpected
realtime delay on task 2". I don't get that error on the original system
with the same configuration.

Regards,
Eric


Two things come to mind.  First, disable hyperthreading.  It's rare for HT
to help at all these days, and for many workloads it's a net loss.  
Second, try restricting Linux from using one core.  You do this by adding a
kernel boot parameter to GRUB: "isolcpus=1" (or "isolcpus=2,3" 
if you leave HT on)  This will prevent Linux from scheduling processes on
the second core.  If you have compiled RTAPI against SMP kernel headers,
then RTAPI will automatically use the highest numbered CPU for realtime
tasks.

If you do this, and don't see much improvement, then here's one more thing
to try.  You'll need two terminals open for this.  In one terminal, enter
the following line:
while true ; do echo "nothing" > /dev/null ; done This will run forever
(until you press ctrl-C), and will chew up CPU cycles on the non-RT core.
Leave that running, and run latency-test in the other terminal.

On the dual-core systems I set up (with Chris' old SMP test kernel), using a
CPU hog on the non-RT core improved things dramatically.



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