htb_class_mode(9)

okay so bestie, welcome to htb_class_mode(9) from the Kernel API Manual — the little function that does a vibe check on an HTB class and reports its current mode. grab a strawberry 🍓 and let’s go.

💖 NAME 💖

htb_class_mode — literally computes and returns the current class mode. no cap, that’s the whole assignment. periodt.

✨ SYNOPSIS ✨

enum htb_cmode htb_class_mode (struct htb_class *cl , s64 *diff );

🎀 ARGUMENTS 🎀

• cl — the target class. that’s the main character here 👑
• diff — diff time in microseconds. yes, microseconds, write it down bestie ⏱️

💅 DESCRIPTION 💅

so the function computes cl’s mode at time cl->t_c+diff and returns it. easy.

if the mode is not HTB_CAN_SEND, then cl->pq_key gets updated to the time difference from now to the time when cl will change its state. iykyk.

also, important little caveat: the class mode does not simply change at cl->{c,}tokens == 0 — there can rather be hysteresis of 0 .. -cl->{c,}buffer range. that’s on purpose: it’s meant to limit the number of mode transitions per time unit. the speed gain is about 1/6. slay for efficiency 🔥

🦋 SEE ALSO 🦋

• Kernel file ./net/sched/sch_htb.c
• htb_classify(9)
• htb_add_to_id_tree(9)
• htb_add_to_wait_tree(9)
• htb_next_rb_node(9)
• htb_add_class_to_row(9)
• htb_remove_class_from_row(9)
• htb_activate_prios(9)
• htb_deactivate_prios(9)
• htb_change_class_mode(9)
• htb_activate(9)
• htb_deactivate(9)
• htb_charge_class(9)
• htb_do_events(9)
• htb_lookup_leaf(9)

mwah 💋 — with love from ./net/sched, dated October 2026. 🫶