Big Linux Patch Series Shakes Up The Scheduler Code For Anyone With Only One CPU Core

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For anyone still happening to have only one CPU core in their system and running a uni-processor "UP" kernel build without any simultaneous multi-processing (SMP) support enabled, a big patch series posted today for the Linux kernel may affect you.Even embedded systems and years-old Intel Celeron processors selling for ~$20 retail these days offer at least two physical CPU cores. The days of having only a single CPU coreandbe running a uniprocessor "UP" kernel configuration are extremely rare in 2025. A patch series posted today to the Linux kernel mailing list is looking to acknowledge the reality of the very rare UP kernel usage in recent years and in turn rely on the SMP kernel scheduler for UP use-cases.It's been two decades since reviewing any single core CPUs on Phoronix.Longtime Linux developer Ingo Molnar posted a set of 43 patches today for standardizing the Linux scheduler on the SMP variant to reduce the complexity and coding mess for dealing with non-SMP cases within the s…