sys_sched_getaffinity(9)

💅 sys_sched_getaffinity(9)

okay so bestie, welcome to the Kernel API Manual ✨ — this one's sys_sched_getaffinity, and it's literally the syscall that tells you which CPUs a process is allowed to run on. like, which ones it's vibing with. 🦋

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✨ NAME ✨

sys_sched_getaffinity — get the CPU affinity of a process 👑

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🌸 SYNOPSIS 🌸

long sys_sched_getaffinity (pid_t pid , unsigned int len , unsigned long
__user * user_mask_ptr );

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🎀 ARGUMENTS 🎀

• pid — the pid of the process. like, which process are we checking on 💖
• len — length in bytes of the bitmask pointed to by user_mask_ptr. so, how much room you're giving it 🫶
• user_mask_ptr — a user-space pointer to hold the current CPU mask. this is where the answer gets dropped off 🎁

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⭐ RETURN ⭐

on success, you get back the size of the CPU mask copied to user_mask_ptr. otherwise, an error code. that's it, that's the whole vibe check 💅

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🌈 SEE ALSO 🌈

• Kernel file ./kernel/sched/syscalls.c — the whole squad lives here 🧚
• task_prio(9)
• idle_cpu(9)
• idle_task(9)
• find_process_by_pid(9)
• sched_setscheduler(9)
• sched_setscheduler_nocheck(9)
• sys_sched_setscheduler(9)
• sys_sched_setparam(9)
• sys_sched_setattr(9)
• sys_sched_getscheduler(9)
• sys_sched_getparam(9)
• sys_sched_getattr(9)
• sys_sched_setaffinity(9)
• sys_sched_yield(9)
• yield(9)
• yield_to(9)
• sys_sched_get_priority_max(9)
• sys_sched_get_priority_min(9)
• sys_sched_rr_get_interval(9)

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ngl, that's the whole page — no plot twists, no secret options, just a syscall doing its little mask-copy thing 🔥

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and that's a wrap, bestie 🫶 this little love letter came from ./kernel/sched, dated October 2026, and it answers to the name sys_sched_getaffinity(9) — periodt 💜✨