What GPIO output latency is typical on a Jetson Nano? What can affect this latency?

We are using Jetson.GPIO (which hits /sys/class/gpio/*/value under the hood) to strobe an LED and measure latency of the CSI camera sensor on our Jetson Nano A02. We would like to make sure that the GPIO output latency — i.e. time between writing 1 to /sys/class/gpio/*/value to the rising edge on the pin — won’t skew our calculation. While our specific use case only cares if the typical GPIO latency will ever be much more than 1ms, generally we’re curious to know what the major components of the GPIO latency are (e.g. if it is CPU-load-dependent). So in fewer words, we want to know:

  1. What is a typical GPIO output latency for a stock Jetson Nano A02 (L4T version 32.6.1)?
  2. What factors can affect this latency and/or cause jitter?

hello derek28,

GPIO controls it should return instantly, it should be system performance issue if CPU is overloaded.
you may have a try to configure the process priority, please check renice tools to alters the scheduling priority, the default priority is zero, the highest priority is -20.
see-also, renice(1) - Linux manual page

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