[email protected] said: > Are you sure about the user-kernel crossings? Because (not 100% sure) I > thought wiringpi access the gpio pins directly - iirc they're memory mapped > (strace doesn't show any system calls) on ARM processors.
Ahh. Thanks for the heads up. I haven't done any bit-banging with the GPIO stuff yet but I want to. I was trying to suggest a way to compare your polling approach with the traditional interrupt method. How about this: Turn off NTP (so it doesn't fiddle with the clock). Collect some data with your polling approach. Collect some data by watching the kernel: Do you know about /sys/devices/virtual/pps/pps0/assert ? Your polling loop will probably heat things up so you probably want to monitor the crystal temperature. Then try running them both at the same time. Try moving the polling around to different CPUs to see if you can find which CPU is doing the interrupt processing. There is probably a way to figure that out. If you haven't discovered it yet, htop is a wonderful tool. For things like this, it tells you which CPU your polling job is running on. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
