vmpressure(9)

💅 vmpressure — the Kernel API Manual page, bestie edition 🎀

okay so picture this: it's vmpressure(9), straight out of the Kernel API Manual, and she's here to tell you all about memory pressure. let's get into it ✨

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🌸 NAME 🌸

vmpressure — literally the function that accounts memory pressure through the scanned/reclaimed ratio. that's the whole vibe. no cap.

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🦋 SYNOPSIS 🦋

void vmpressure (gfp_t gfp , int order , struct mem_cgroup *memcg , bool
tree , unsigned long scanned , unsigned long reclaimed );

look at her. six arguments. main character energy fr fr 👑

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✨ ARGUMENTS ✨

• gfp — the reclaimer's gfp mask. yes, that gfp. iconic.
• order — the allocation order that's being reclaimed for 🫶
• memcg — the cgroup memory controller handle 💖
• tree — legacy subtree mode. she's a bool, she's got history, we respect her 🙈
• scanned — how many pages got scanned 🔍
• reclaimed — how many pages got reclaimed 🎀

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💜 DESCRIPTION 💜

okay so the tea ☕: you should be calling this function from the vmscan reclaim path, because its whole job is to account for "instantaneous" memory pressure — that's the scanned/reclaimed ratio, bestie. and then? the raw pressure index gets further refined and averaged over time. she doesn't just give you the instant read, she gives you the whole arc 📈✨

now here's where it gets interesting 👀

if tree is set, vmpressure is in traditional userspace reporting mode — meaning memcg is considered the pressure root, and userspace gets notified about the entire subtree's reclaim efficiency. big group-chat energy, everyone gets the message 🫶

if tree is not set, then reclaim efficiency is recorded for memcg, and only in-kernel users are notified. lowkey exclusive. iykyk 💅

and bestie, this function does not return any value. it's void. she gives, she doesn't take 😌

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🔥 SEE ALSO 🔥

• Kernel file ./mm/vmpressure.c
• vmpressure_init(9)
• vmpressure_cleanup(9)

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and that's the whole page, bestie 🧚 ngl she ate. this one's brought to you by ./mm, dated October 2026 — slay, see you in the next manpage 💖🌈⭐