Hi, I try to do some basic performance test of RTnet
What correspond exactly TDMA_CYCLE and TDMA_OFFSET ?
TDMA_CYCLE is the period length in microseconds of a basic cycle. The master station sends a Start of Frame (SOF) packet at the beginning of a new cycle. Each station has one time slot per cycle, its offset to the SOF is defined by multiple of TDMA_OFFSET (master = 0*offset, 1. station = 1*offset, ..., n. station = n*offset).
here is a test with TDMA_CYCLE=500 and TDMA_OFFSET="50"
ip address 192.168.10.3=c0a80a03
Warniinterval = 500 ng: loading rt_cpacketsize = 58 Roundtrip = 504us (min: 504us, max: 504us) Roundtrip = 23902us (min: 504us, max: 23902us) Roundtrip = 502us (min: 502us, max: 23902us) Roundtrip = 24100us (min: 502us, max: 24100us) Roundtrip = 500us (min: 500us, max: 24100us) Roundtrip = 500us (min: 500us, max: 24100us) Roundtrip = 24099us (min: 500us, max: 24100us) Roundtrip = 498us (min: 498us, max: 24100us) Roundtrip = 26097us (min: 498us, max: 26097us) Roundtrip = 496us (min: 496us, max: 26097us) Roundtrip = 26097us (min: 496us, max: 26097us) Roundtrip = 497us (min: 496us, max: 26097us)
it's no real-time
Well, it is real-time - as long as you can live with 26 ms latency.
Ok, I also don't think that this is acceptable. Are you sure that the hardware latency of all involved systems does not have any quirks?
When a try whit default setting
the round trip is = 7000�s but it lost 1�s evry seccond.
Are you measuring the round trip delay on the master or one some other node? If it is not the master, you just quantified the drift between both clocks.
As with the default parameter set you don't suffer from high jitters, I assume that the scheduling may overrun with the faster setup. Try to play a bit with TDMA_OFFSET, maybe also with TDMA_CYCLE. What are the "naked" round trip times of your systems (i.e. without RTmac/TDMA)? This may give you some idea about the system load caused by RTnet. Typical times on Pentium I systems (>= 133 MHz, PCI adapters, no other busmastering DMA enabled) are around 100 us.
Jan
------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id70&alloc_id638&op=click _______________________________________________ RTnet-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/rtnet-users
