Hi, I am running Xenomai 2.4.7 and linux-2.6.28 on ATMELs AT91SAM9G20-EK. I noticed a strange thing while measuring IRQ latency with a logic analyser. Basically I just insert a module with insmod into the kernel. The module creates an interrupt with "rt_intr_create" and the isr only triggers a gpio pin up and down.
I also turned I- and D-caches off to avoid the effects of cache-flushes on a context switch. If the kernel runs the idle process (cpu_idle) the latency is about 2us larger than with a load. It seems be irrelevant what kind of load I generate. To generate load I am now using a "stress" application I found. The simplest case is that it runs a loop and calls the rand() function. The "idle"-latency is about 25us in this case and the "stressed" one about 23 us. If i run the same test on a kernel without the xenomai extensions i dont get an difference between the latencies. Has anyone any ideas why this is happening? Best Regards, Karl Tyss Mit Freundlichen Grüßen, Karl Tyss --------------------------------------------------------------------------------------- This email including its attachments is intended for the person or entity only to which it is addressed. It may contain confidential and/or privileged material. Any review, forwarding, dissemination, other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this email in error, please contact the sender and delete the material from any computer system. --------------------------------------------------------------------------------------- Eppendorf AG, Hamburg, Barkhausenweg 1, 22339 Hamburg, Amtsgericht Hamburg HRB 76249 Vors. des Aufsichtsrats: Dipl.-Ing. Adrian Déteindre Vorstand: Klaus Fink (Vorsitzender), Detmar Ammermann, Dr. Heinz G. Koehn, Dr. Michael Schroeder Eppendorf Instrumente GmbH, Hamburg, Amtsgericht Hamburg, HRB 69077 Geschäftsführer: Rainer Treptow Eppendorf Biochip Systems GmbH, Hamburg, Amtsgericht Hamburg, HRB 96641 Geschäftsführer: Dr. Sven Buelow Eppendorf Liquid Handling GmbH, Hamburg, Amtsgericht Hamburg, HRB 92250 Geschäftsführer: Boris von Beichmann _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
