this post was submitted on 29 Feb 2024
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From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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I've been working on that exact problem for the last couple weeks. My solution for now is rt patch and a dedicated cpu core for rt tasks. This already works pretty reliable, but I notice small delays from time to time. I gather from the article that my problem might be page swapping. I don't know how to improve that, yet.
Also for anybody working on rt problems: I highly recommend the
stress-ng
tool for stress testing and finding bottlenecks of your system.If you're working on something that truly needs faster response times at the kernel, you might be better off looking at Zephyr or FreeRTOS for more consistency. "Real-time" mode in the plain Linux sense is just a series of patches which work towards one goal (skipping schedulers and such), but not all coherently working together. Other RTOS's out there are designed from the outset to streamline such things.
That's why many modern SoCs have a smaller core for realtime in addition to larger application processors. TI Sitara (Beaglebone) has 2 fast custom arch coprocessors for IO with access to most pins and the ability to DMA into the AP's address space. All Raspberry Pis up through Pi4 run a proprietary ThreadX runtime on a graphics processor (VPU) to handle bootstrapping the ARM APs, housekeeping, and a large part of the IO.
K. Cool.
But how does this answer OPs questions?