RT/Linux SCHED_RR/_FIXED to combat latency?

[Thorsten Glaser]

On Thu, 10 Aug 2023, Cedric Blancher wrote:

>We're experiencing rather very bad latency spikes on busy Linux
>systems, for example if one machine is the jumphost (ssh -J) for a few
>hundred connections, while at the same time handles CPU intensive
>tasks.
>
>Would RT/Linux SCHED_FIXED or SCHED_RR be of help in such a case, e.g.

Did you already check the old and tried method of nice(2)?

If the other load is CPU-intensive, this is usually sufficient.

Normally you’d nice the CPU-intensive load (so anything else on
the system is not affected), but you can also negative-nice the
sshd processes (and therefore, the children) which however may
not be sufficient and could require to negative-nice some other
processes or kernel tasks as well, so see if your scenario can
just positive-nice the load instead.

gl hf,
//mirabilos
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