On Mon, Jan 28, 2002 at 04:06:16PM +0100, Paolo Mantegazza wrote: > Arni Ingimundarson wrote: > > > > Hello, > > > > I was asked to demonstrate RTLinux to research group at the university > > (TU-Darmstadt). They are now using proprietery RT OS. > > > > All wenn well and we had usually about 5us irq latency. The problem > > was every now and then the latency got as high as 20-25 micro seconds. > > > > That is way to much. > > > > I was running this on a Intel Celeron 300A with ISA timercard giving > > interrupt and the IRQ-handler sending one pulse to the Parallel-Port. > > RedHat 7.2 with RTLinux 3.1 on Kernel 2.4.4 and KDE. (I know ISA isn't > > the best for RT but it shouldn't matter with this test). > > > > My question is: Is it known what programs/tasks could be blocking > > interrupts? Wouldn't it be possible to not run those programs to > > guaranty shorter responce time ? > > > > I would apreciate any info. > > The real question is: what do the proprietary OS they use attain on the > same hardware for the same test?
I did not try it myself, but the claim worst case < 10us with avarage about 5us. Someone even claimed he got about 2,5us. > Note that those 20 us are not so bad and are there to stay for ever. > They can disappear just if you can spoil your system of anything and use > very fast, likely non ISA, cards. I know PCI and PowerPC have better responce time, but at this time it is not an option to buy new hardware. I was hoping this to be a software problem, which one could fix. Regards, Arni [EMAIL PROTECTED] -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/
