__scx_bpf_dsq_insert_vtime(9)

📦 version 7.3.1, in nixpkgs unstable

💅 __scx_bpf_dsq_insert_vtime — okay bestie, listen

Welcome to the Kernel API Manual, section 9, and honestly? This one is a little bit of a diva. Her whole thing is arg-wrapped vtime DSQ insertion — yes that's the NAME, yes we're keeping it, no we're not renaming her. 🎀

✨ NAME ✨

__scx_bpf_dsq_insert_vtime — Arg-wrapped vtime DSQ insertion. That's it, that's the vibe. Put a task in a vtime-sorted queue, but with the arguments wrapped up in a struct because BPF said "five arguments max, bestie, I don't make the rules." 💀

🌸 SYNOPSIS 🌸

__bpf_kfunc bool __scx_bpf_dsq_insert_vtime (struct task_struct *p ,
struct scx_bpf_dsq_insert_vtime_args *args , const struct bpf_prog_aux
*aux );

Like, look at her. Three arguments, one of which you literally cannot touch. Main character energy fr fr. 🔥

🦋 ARGUMENTS 🦋

  • p — the task_struct you're inserting. Your little guy. Your blorbo. 🫶
  • args — the struct holding the rest of the arguments, because we ran out of argument slots and had to get creative:
    • args->dsq_id — the DSQ you're inserting into. The destination, the venue, the location tag. 📍
    • args->slice — how long p can run for, in nsecs. Set it to 0 to keep the current value. Zero is giving "no thoughts, head empty, keep what's already there." 🙈
    • args->vtime — p's ordering inside the vtime-sorted queue of the target DSQ. Her little place in line. ⭐
    • args->enq_flags — SCX_ENQ_* flags. You know the ones.
  • aux — the implicit BPF argument, so you can access bpf_prog_aux. She's hidden from BPF progs — you don't call her, she just shows up. Lowkey mysterious. 💜

💖 DESCRIPTION 💖

So. Wrapper kfunc. It takes its arguments via a struct to work around BPF's 5 argument limit — iconic workaround, no notes. 💅

Real talk: BPF programs should not call this directly. Use scx_bpf_dsq_insert_vtime, which is provided as an inline wrapper in common.bpf.h. That's the one you actually want, bestie. This one is the plumbing.

Okay so what does she do? She inserts p into the vtime priority queue of the DSQ identified by args->dsq_id. Tasks queued into the priority queue get ordered by args->vtime. Everything else? Absolutely identical to scx_bpf_dsq_insert. Same girl, different queue. ✨

The args->vtime ordering goes according to time_before64, which considers wrapping. So a numerically larger vtime can actually mean an earlier position in the ordering, and vice-versa. Yes, that's real. Yes, it's a little mind-bending. No, you're not bugging. 😭

Careful though!! A DSQ can only be used as a FIFO or a priority queue at any given time. So you must not call this function on a DSQ which already has one or more FIFO tasks queued — and vice-versa. Don't mix, it's not a vibe. Also: the built-in DSQs (SCX_DSQ_LOCAL and SCX_DSQ_GLOBAL) cannot be used as priority queues. Periodt.

Returns true on successful insertion, false on failure. 🎀 And here's the cute part — on the root scheduler, a false return triggers a scheduler abort, so the caller doesn't even need to check the return value. She handles it. She's got you. 👑

🌈 SEE ALSO 🌈

Kernel file ./kernel/sched/ext/ext.c, plus literally her entire extended friend group. Not me listing all of them. Okay I'm listing all of them. 💀

Okay that's the whole page, you ate that. 💜 She lives in ./kernel/sched/ext, this is the October 2026 edition, and that's the whole manual-name-and-date situation handled — mwah, bye bestie! 🧚🌸

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