> Mica Hallin schrieb: > > 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?
Hi, I just want to give a nice example to this: I'm using RTNET together with pcmcia_cs package on an embedded system. Pcmcia_cs's Configure script is reading some configuration from .config and generates an own config.h file, but does not worry about CONFIG_RTHAL. After including asm/system.h the pcmcia_cs modules are using the hard cli() and sti() macros and damage the hard realtime ability of RTAI/RTNET. I got an inacceptable jitter of about 1.3ms on a 2.4kHz UDP output. Be shure if you are using driver packages outside of the kernel tree, that they are behaving the right way regarding the usage of a RTHAL! Arno > > > 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 -- +++ NEU bei GMX und erstmalig in Deutschland: T�V-gepr�fter Virenschutz +++ 100% Virenerkennung nach Wildlist. Infos: http://www.gmx.net/virenschutz ------------------------------------------------------- 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_id=1470&alloc_id=3638&op=click _______________________________________________ RTnet-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/rtnet-users
