STRUCT SYNC_SET_DEADLINE(9)

💅 struct sync_set_deadline(9) — the kernel API manual, but make it make sense

okay bestie, so we're deep in the kernel API manual today, and this one is a struct, not a function — it's struct sync_set_deadline, the little guy behind SYNC_IOC_SET_DEADLINE. And what does it do? It sets a deadline hint on a fence. That's the whole vibe. 🎀

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✨ SYNOPSIS ✨

here's the shape of it, literally, copy it exactly, no cap:

struct sync_set_deadline {
    __u64 deadline_ns;
    __u64 pad;
 };

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🦋 Members 🦋

• deadline_ns — the absolute time of the deadline. absolute, okay? not "in 5 seconds", it's the actual moment. ⏰
• pad — must be zero. that's it, that's the whole job. zero. nada. 🫶

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🌸 Description 🌸

so this struct lets userspace set a deadline on a fence — and if you wanna know the deep lore, go look at dma_fence_set_deadline. iykyk. 🔥

now the important bit, the timebase for the deadline is CLOCK_MONOTONIC (same as vblank). periodt. 💅

for example:

clock_gettime(CLOCK_MONOTONIC, t); deadline_ns = (t.tv_sec *
1000000000L) + t.tv_nsec + ns_until_deadline

that's the math, bestie — take your monotonic clock reading, multiply the seconds by 1000000000L, add the nanoseconds, plus however many ns_until_deadline you got left. slay. ✨

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👑 SEE ALSO 👑

• Kernel file ./include/uapi/linux/sync_file.h
• struct sync_merge_data(9)
• struct sync_fence_info(9)
• struct sync_file_info(9)

go read those, they're iconic too. 🌈

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lowkey reminder: pad is not decoration, it must be zero — don't be the one who breaks it. 💀

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and that's the whole page, bestie — source lives at ./include/uapi/linux, dated October 2026, 🦋 mwah, go set some deadlines responsibly 💜