trace_timer_expire_entry(9)

💅 trace_timer_expire_entry — kernel API manual, bestie edition

okay so real talk, this is trace_timer_expire_entry(9) from the Kernel API Manual, and she is a tracepoint hook, not a function you call yourself — she fires for you. Let's get into it ✨

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🌸 NAME

trace_timer_expire_entry — called immediately before the timer callback 🎀

✨ SYNOPSIS

void trace_timer_expire_entry (struct timer_list *timer , unsigned long
baseclk );

literally that's the whole vibe: returns void, takes two args, no notes 💅

🫶 ARGUMENTS

• timer — pointer to struct timer_list. yeah. that's the timer. the main character of this whole situation 👑
• baseclk — the value of timer_base::clk when the timer expires. that's it, that's the whole field, respect her 🕐

🦋 DESCRIPTION

bestie. this one is so simple and so iconic. it lets you determine the timer latency. that's the entire job description. measuring how long the timer took to actually get there vs. when it was supposed to 🔥

ngl, no extra lore here — the whole point is the latency measurement, and that's all the page gives us. periodt.

🌈 SEE ALSO

the kernel file lives at ./include/trace/events/timer.h, and here's the whole friend group, all of them, no cap:

• trace_timer_init(9)
• trace_timer_start(9)
• trace_timer_expire_exit(9)
• trace_timer_cancel(9)
• trace_hrtimer_setup(9)
• trace_hrtimer_start(9)
• trace_hrtimer_expire_entry(9)
• trace_hrtimer_start_expired(9)
• trace_hrtimer_expire_exit(9)
• trace_hrtimer_cancel(9)
• trace_hrtimer_rearm(9)
• trace_itimer_state(9)
• trace_itimer_expire(9)

go read them, they're all right there, iykyk 💖

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okay that's the page!! this one came from ./include/trace/events, dated October 2026, and she's filed under trace_timer_expire_entry(9) — mwah, slay, go measure some latency bestie 🧚💜