
Ask HN: How to use Linux as a quasi real time system - FrojoS
I&#x27;ve heard, that e.g. SpaceX use Linux on many of their flight computers. For instance, what hardware and what software tweeks are used to allow sampling of sensor data with a fixed frequency?
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seren
You can use Linux with the Preempt RT patch or Xenomai, which is using a kind
of micro kernel in addition to the Linux Kernel. The downside is you have to
rewrite your drivers for Xenomai.

I thought that the latter was better in terms of performance but the article
below seems to affirm they are not that big. (but it is coming from the
Preempt RT side)

[http://linuxgizmos.com/real-time-linux-
explained/](http://linuxgizmos.com/real-time-linux-explained/)

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PaulHoule
The basic tweak is overprovisioning. If the computer is not busy it will get
tasks done on time and not freeze up. If it has too much work to do in a time
frame than it is not going to get it all done. The one thing it can really do
differently is abort a task early when it is clear that that task can't be
done on time, but then you will get complaints from the people whose tasks are
responsible from that task completing.

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Jack000
for PCs you can try the jitter measurement from linuxcnc
[http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-
Test](http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-Test)

