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linux-rt is a patchset that changes the behavior of linux to increase the number of places where preemption can occur (among other things).

Doing this decreases certain types of latency in certain situations. As an example, it tries to have interrupts disabled less frequently and for shorter intervals, and uses mutexes instead of spinlocks.

As a result, using linux-rt can provide a lower latency experience compared plain linux.

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Ah, that's fair enough, but it isn't 'real time', which is the thing I was assuming from the 'RT' in the name. Perhaps linux-ll would be a better name, for 'low latency'. RT just confuses what it is trying to do.

It is trying to make the linux kernel more real time capable. Having periods of time where preemption isn't enabled (due to having interrupts disabled, etc) results in more variation in when tasks are scheduled, including real time tasks.

The reality is that "real time" as a definition covers many "features" and design choices because many ducks need to be in a row for real time tasks to run properly. Decreasing variation in the scheduling of (real time) tasks is one of those items.

As a result, it's entirely reasonable to call "linux-rt" "linux-rt".

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