bfq_update_active_node(9)

📦 version 7.3.1, in nixpkgs unstable

🦋 bfq_update_active_node(9) — like, the glow-up page for a node's min_start ✨

okay so before we even start: this is from the Kernel API Manual, section 9, and the whole page is literally about giving one lil red-black-tree node a lil refresh 💅 stay with me bestie, it's shorter than it looks.

🌸 NAME 🌸

bfq_update_active_node — recalculate min_start.

🎀 SYNOPSIS 🎀

void bfq_update_active_node (struct rb_node *node );

💖 ARGUMENTS 💖

  • node — the node to update. that's it. that's the whole argument list, she's low maintenance 🫶

✨ DESCRIPTION ✨

so here's the vibe check: node may have changed position, or one of its children may have moved. when that happens, this function swoops in and updates its min_start value 🧚

and here's the important part — a precondition, not a suggestion: the left and right subtrees are assumed to hold a correct min_start value. the function is trusting you on that fr fr. it's not re-checking the kids, it's just fixing up the parent's number 💅

ngl this one is the "recompute after the tree shifted" helper, and it assumes the subtrees underneath are already slaying correctly before you call it 👑

🌈 SEE ALSO 🌈

Kernel file ./block/bfq-wf2q.c — and the whole extended friend group:

and that's the whole page, bestie 🍓 sign-off time: this lil number lives under the ./block source, dated October 2026, and yes it's bfq_update_active_node(9) again because we always bring it back to her 👑✨ iykyk 💜

📦 where this page comes from