STRUCT IRQ_AFFINITY(9)

💅 struct irq_affinity(9) — like, the whole vibe

okay so bestie, welcome to the Kernel API Manual page for struct irq_affinity(9) — yes that's the actual manual name, we're in the kernel docs now, main character energy only 🫶

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✨ NAME ✨

struct irq_affinity — the description you hand the kernel so it can do automatic irq affinity assignments for you, no cap 💖

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🌸 SYNOPSIS 🌸

struct irq_affinity {
    unsigned int    pre_vectors;
    unsigned int    post_vectors;
    unsigned int    nr_sets;
    unsigned int    set_size[IRQ_AFFINITY_MAX_SETS];
    void (*calc_sets)(struct irq_affinity *, unsigned int nvecs);
    void *priv;
 };

like, that's the whole struct, literally copy it into your brain bestie 🧠✨

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🎀 Members 🎀

(these are the fields, and yes every single one matters, don't skip 🙈)

• pre_vectors — don't apply affinity to pre_vectors at the beginning of the MSI(-X) vector space. it's giving "leave the opening act alone" 💅
• post_vectors — don't apply affinity to post_vectors at the end of the MSI(-X) vector space. closing act stays untouched too 🎭
• nr_sets — the number of interrupt sets for which affinity spreading is required. count your sets, bestie 🔢
• set_size — an array holding the size of each interrupt set. every set gets its own little size slot 🍓
• calc_sets — callback for calculating the number and size of interrupt sets. the function signature is literally void (*calc_sets)(struct irq_affinity *, unsigned int nvecs); — it does the math so you don't have to 🧮✨
• priv — private data for usage by calc_sets, usually a pointer to driver/device specific data. it's your little secret stash, iykyk 🤫

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🔥 SEE ALSO 🔥

go touch some of these next, they're all iconic 👑

• Kernel file ./include/linux/interrupt.h struct irqaction(9)
• request_irq(9)
• struct irq_affinity_notify(9)
• struct irq_affinity_desc(9)
• irq_update_affinity_hint(9)
• irq_set_affinity_and_hint(9)

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and that's the page bestie!! 💜 it lives in ./include/linux and the version stamp says October 2026 — so like, future-core of you to be reading this fr fr. slay, go set some affinities, mwah 🎀💖🌈