set_comm_cgroup(9)

💅 set_comm_cgroup(9) — the Kernel API Manual, bestie edition 🎀

okay so this is set_comm_cgroup, a little function living in the Kernel API Manual (section 9, kernel-dev vibes only ✨). It's the one that grabs threads by their name prefix and yeets them into a cgroup. Let's get into it 🦋

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🌸 NAME 🌸

set_comm_cgroup — set the cgroup for all the threads whose names start with char *comm_prefix 💖

Literally what it says on the tin: you give it a prefix, it goes and finds the matching threads, and moves them into a cgroup. iconic behaviour tbh 👑

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✨ SYNOPSIS ✨

int set_comm_cgroup (const char *comm_prefix , const char *cgroup );

that's the whole signature, no cap — two const char * args and it hands you back an int 🫶

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🎀 ARGUMENTS 🎀

• comm_prefix — ngl the man page itself just says -- undescribed -- 😭 so like, the prefix that thread names get matched against, per the NAME section. That's all we've got, bestie, don't come for me 🙈
• cgroup — also literally -- undescribed -- 💀 see DESCRIPTION for what it actually does with it, that's where the lore is ✨

fr fr these two are marked undescribed in the source page, so I'm not out here inventing details. staying in my lane 💅

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🔥 DESCRIPTION 🔥

okay so here's the tea ☕

If the cgroup argument is not NULL, the threads will move to the given cgroup. slay, that's the main character behaviour right there 👑

Otherwise — like, when cgroup is NULL — the cgroup of the calling thread will be used. and by "the calling thread" we specifically mean rtla, iykyk 🧚

It supports cgroup v2. only v2, so don't come at it with your legacy cgroup v1 energy, it's not the vibe 🌈

Returns 1 on success, 0 otherwise. that's it. one for yes, zero for nope 🍓

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🦋 SEE ALSO 🦋

• Kernel file ./tools/tracing/rtla/src/utils.c
• auto_house_keeping(9)

go read those if you want the full picture, bestie 📚✨

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and that's the whole page!! mwah 💋 this lil gem comes from ./tools/tracing/rtla/src, dated October 2026 — so like, future vibes 👑🫶 periodt 💜