Back in May a big patch series was published for reworking the Linux kernel to make the SMP support unconditional. Right now those that happen to be running Linux in a uniprocessor (1 CPU core) configuration can build with “CONFIG_SMP” disabled but the proposed patches would make symmetric multi-processing support always present. Those patches took a step forward this week and could be merged for the Linux 6.17 cycle later in the summer.
The patches adapt the Linux kernel scheduler to the SMP variant so that “CONFIG_SMP” is in effect always enabled and unconditional. This makes sense since the absolute vast majority of modern systems in recent years are 2+ CPU cores for those still upgrading to newer Linux kernel releases. Even multi-core systems are very common in embedded environments.
This rework reduces kernel complexity for maintenance and ongoing development. But for anyone running in a uniprocessor world, making SMP unconditional does lead to some slight overhead. But again the number of uniprocessor systems in 2025+ running a single core processor and upgrading to new mainline Linux kernel releases is especially tiny.
The step forward this week is the SMP unconditional patches have been picked up by tip/tip.git’s sched/core Git branch. With the patches being picked up by the TIP tree in branch with plans to submit them for the Linux 6.17 merge window, the change could happen for the next kernel cycle.
The Linux 6.17 merge window won’t be until early August and it still needs to be okay’ed by Linus Torvalds, but these unconditional SMP support patches stand good chances of being merged for Linux 6.17 now that they’ve made it into a “-next” branch.
