Oh yes :), for low latency, you also need to set up BIOS settings properly, disabling and enabling a lot of things, setting PCI latency to 32, etc.
Did you do this part? What I know/heard about 2-core RTAI support, that it is experimental, I did not yet hear of production version. As for low latency, I did achieve a 5.7 microsecond KLAT MAX measured with PIRT on a K7 processor running at maybe 2200MHz (Athlon XP something), it was nForce3 chipset. Also my notebook with SiS 740/650 chipset with Athlon XP (lovely Palomino) gets maybe 7-14 microsecond latencies at 1GHz. I don't remember exactly.. It was some time ago. So for low latency, you need a FAST queue, the FETCH queue, the CACHE queue, the CHIPSET memory and interrupt management queue. It is a lot more that just raw processor power. So you need adequate ratio of: 1) Processing power/queue size and delays 2) low communication and memory latency So, for Athlon AM2 you seem to use, you need to get the highest HTT you can - the VIA mainboard you seem to use allows for only 20% overclock, which works without a glitch anyway, you will want to try different combination of memory settings and processor speed/multiplier. DDR2 memory with 800"MHz" DDR2 CL4 latency would be advisable. You can not count on higher latency memory modules to deliver very good RTAI latencies ;-) Mario out. On 1/13/07, Ray Henry <[EMAIL PROTECTED]> wrote: > > Hi Per > > No help on the SMP compile and run. I don't have such a mobo here. I > do have an Athalon64 on a N8V mobo. I do not see any big jump in > latency every 6 or so iterations of the test. > > I must admit when running with an 8000 base period that I was violating > the sentence in the troubleshooting wiki page > > http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?TroubleShooting > > "There should be no overruns, and 'lat max' should probably be > below your BASE_PERIOD setting." > > I did not see any overruns from the latency test but the 8000 was below > the 12000 lat max for that box. > > Rayh > > > On Sat, 2007-01-13 at 15:07 +0100, Per Willför wrote: > > Hi! > > > > I've got some serious problems to build an SMP kernel with RTAI > > extensions, and I'm thinking that maybe someone else may have already > > achieved this. I have a system with an Athlon 64 X2 4600+ on an Asus M2V > > motherboard (K8T890 chipset), and I'm using Ubuntu 6.06.1 LTS with EMC2 > > loaded per the script on the linuxcnc.org homepage. Everything works > > just great in UP mode, but I'm missing the additional processor that > > sits there idle. My goal is to squeeze BASE_PERIOD as low as possible > > (to get the highest stepping freq possible, or less jitter for lower > > step rates), and I think an SMP kernel wold help substantially in this > > regard. In UP mode BASE_PERIOD can only be lowered to about 20 µs, and I > > would like to get down to 5-8 µs - I read a post by Ray H that he set > > BASE_PERIOD to 8000... When I run the RTAI test program (have forgot > > it's name) i get good delay numbers for 4-5 rows and then there's > > something that "gets in the way" every 5th - 6 th row with much longer > > latencies. My idea was to not optimize the interrupt handling and > > graphics drivers or whatever, but rather enabling the other CPU. Having > > tried all sorts of magma as well as vanilla kernels, it always fails > > when I use the combination of SMP and RTAI. > > > > For starters, I thought I could just use the magma kernel source and > > change one thing - enable SMP - but this wasn't the case. The machine > > just rebooted after i selected "magma-smp" in GRUB, if there was any > > error message flashing by I'm not fast enough to read it. About the same > > problems has occured with different vanilla kernels as well, sometimes > > the machine just reboots after GRUB selection, sometimes I get some > > output from the kernel before it freezes or crashes (BTW, is there a way > > to capture the console output, like "tee:ing" it to a serial port?) > > > > Please note that I haven't come as far as trying to start EMC2 on an SMP > > kernel; I'm still trying to boot a kernel with SMP enabled and RTAI > > patches. For the vanilla kernels I have been using rtai-3.4-cv and > > 2.6.17.6 (I started with 2.6.17.14 and went backwards unit the patch > > file from RTAI could be applied without errors). > > > > What am I doing wrong? > > > > Per W > > SWEDEN > > -- > > > > > > ------------------------------------------------------------------------- > > Take Surveys. Earn Cash. Influence the Future of IT > > Join SourceForge.net's Techsay panel and you'll get the chance to share > your > > opinions on IT & business topics through brief surveys - and earn cash > > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. Influence the Future of IT > Join SourceForge.net's Techsay panel and you'll get the chance to share your > opinions on IT & business topics through brief surveys - and earn cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
