__perf_evsel__calc_is_pos(9)

💅 NAME 💅

Bestie, welcome to __perf_evsel__calc_is_pos — the little kernel helper whose whole personality is calculating is_pos. That's it, that's the job. ✨ (And yeah, this page lives in the Kernel API Manual, so you know it's fancy.)

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🌸 SYNOPSIS 🌸

int __perf_evsel__calc_is_pos (u64 sample_type );

Like, that's the whole signature. One argument, one int coming back at you. Iconic minimalism. 🎀

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🦋 ARGUMENTS 🦋

• sample_type — the sample type. It gets passed in, it does its thing, no notes. 💅

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✨ DESCRIPTION ✨

Okay so here's the tea, bestie: this function returns the position — and not just any position, we're counting backwards here — of the event id (PERF_SAMPLE_ID or PERF_SAMPLE_IDENTIFIER) inside a non-sample event. 🫶

Why does that matter, you ask? Because when sample_id_all is used, there's literally an id sample appended to non-sample events. So the id is hanging out at the end, and this function knows exactly where to find it. Main character energy fr fr. 🔥

Ngl, the "counting backwards" bit is the whole vibe check of this function — don't forget it. 🧚

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👑 SEE ALSO 👑

• Kernel file ./tools/perf/util/evsel.c — __perf_evsel__calc_id_pos(9)
• evsel__is_function_event(9)
• evsel__clone(9)
• evsel__is_hybrid(9)

All the linked besties, no gatekeeping. 💖

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slay, you made it to the end 🎉 This page came from ./tools/perf/util, dated October 2026, and it's filed under __perf_evsel__calc_is_pos(9) — periodt. 💜