[etherlab-users] general performance questions

[Georg Sassen]

Hi,

since we are trying to optimize our systems, some general questions
arise again, as perhaps the answers have changed over the time. We are
using Ubuntu 8.04 with RT patches, with Ubuntu stock kernel 2.6.24-rt,
and EtherCAT master from about a month ago.

1) Which Ethernet card is best suited for the EtherCAT master when using
large process data and fast EtherCAT cycles? We had some problems with
the E1000: When using lots (>100) of domains, we got many EtherCAT
datagram timeouts and the process EtherCAT-OP used nearly all of the CPU
(1.86GHz Celeron). This got better when we put in a cheap 8139 card -
but we still see these errors from time to time and don't really know
where they come from.

2) Is using the RT PREEMPT kernel still ok? I don't read much about
other people using it here, most seem to be using RTAI?
If using RT PREEMPT, are there any special options to be set in the
system or are the default settings ok?

3) Would changing to a newer kernel (like 2.6.31-rt with Ubuntu 10.04)
make a difference performance-wise?

Thanks

   Georg