[HN Gopher] Ask HN: How to get started with real-time Linux?
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       Ask HN: How to get started with real-time Linux?
        
       I would like to learn and work on both software and hardware of
       real-time Linux. Any books or projects do you recommand for getting
       started?
        
       Author : withoutsnow
       Score  : 11 points
       Date   : 2022-10-02 18:48 UTC (4 hours ago)
        
       | FlashPackets wrote:
       | Your best starting point in LinuxCNC it may very well be the
       | single greatest application for real time linux
        
       | Wesmio wrote:
       | You are aware that real time only means guaranteed right?
       | 
       | What is your goal as this is a broad field?
       | 
       | If you wanna just start with it, I would try to read up on cars,
       | can Bus and how all of that works.
        
         | mmsnberbar66 wrote:
         | Is Linux a popular option for real-time? Or are other OS more
         | relevant in this field?
        
           | jeffreygoesto wrote:
           | Depends how "hard" realtime we're talking. For tighter
           | deadlines you'd usually use QNX or PikeOS or the like. The
           | bigger issue is that for higher task frequencies you probably
           | don't want to use big microprocessors, but microcontrollers
           | that don't have a MMU but a MPU max. That rules out Linux
           | quite often (plus space constraints).
        
           | joezydeco wrote:
           | FreeRTOS is a better choice in a lot of circumstances. But
           | you don't get a driver ecosystem like Linux.
           | 
           | In embedded the trend is heading toward heterogenous systems,
           | where you have an application processor running Linux and a
           | coprocessor (sometimes on the same die) that runs an RTOS.
        
       | pwnna wrote:
       | I found this to be hard-ish to get started as well. However, it
       | turns out you just need to write your program to be performant,
       | and know a few tricks to tune the OS and the scheduler. After
       | looking on the internet and failing to find material about this,
       | I wrote a series of blog post for this topic recently, starting
       | with this post: https://shuhaowu.com/blog/2022/01-linux-rt-
       | appdev-part1.html
       | 
       | The series is mostly complete, except one to two posts on more
       | advanced topics like validation and lockless programming.
        
         | skyde wrote:
         | Real-time software does not mean fast software! It mean
         | determinism, guarantee that each time it run it will never take
         | more than x milliseconds to complete. Those guarantee are very
         | hard when considering a system like linux with many background
         | process or thread each randomly doing IO and allocating memory.
        
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       (page generated 2022-10-02 23:01 UTC)