STRUCT RMID_READ(9)

🎀 NAME 🎀

okay so bestie, this is the struct rmid_read(9) page from the Kernel API Manual, and it’s literally all about struct rmid_read — Data passed across smp_call*() to read event count. no cap, that’s the whole vibe. 💅

✨ SYNOPSIS ✨

here’s the struct in all its glory — copy it exactly, character for character:

       struct rmid_read {
           struct rdtgroup         *rgrp;
           struct rdt_resource     *r;
           struct rdt_domain_hdr   *hdr;
           struct mon_evt          *evt;
           bool first;
           struct cacheinfo        *ci;
           bool is_mbm_cntr;
           int err;
           u64 val;
           void *arch_mon_ctx;
        };

🧚 Members 🧚

• rgrp — the Resource group for which the counter is being read. If it’s a parent resource group, then its event count gets summed with the count from all its child resource groups. family reunion math, fr fr 👑
• r — the Resource describing the properties of the event being read. it’s giving “what are we even reading” energy.
• hdr — Header of the domain that the counter should be read from. If it’s NULL, then sum all domains in r sharing L3 ci.id. okay periodt.
• evt — Which monitor event to read. pick your fave, bestie.
• first — Initialize MBM counter when true. tiny but iconic.
• ci — Cacheinfo for L3. Only set when hdr is NULL. Used when summing domains. lowkey the helper for the NULL case 🫶
• is_mbm_cntr — true if "mbm_event" counter assignment mode is enabled and it is an MBM event. yes, it said what it said 💀
• err — Error encountered when reading counter. if this pops off, something went sideways 😭
• val — Returned value of event counter. If rgrp is a parent resource group, val includes the sum of event counts from its child resource groups. If hdr is NULL, val includes the sum of all domains in r sharing ci.id, (summed across child resource groups if rgrp is a parent resource group). that’s the whole tea ☕
• arch_mon_ctx — Hardware monitor allocated for this read request (MPAM only). special guest star energy 🌟

🔮 SEE ALSO 🔮

go peek at the Kernel file ./fs/resctrl/internal.h, plus cpumask_any_housekeeping(9), struct mon_evt(9), struct mon_data(9), enum rdtgrp_mode(9), struct mongroup(9), struct rdtgroup(9), struct rftype(9), and struct mbm_state(9). iykyk 🌈

mwah 💋 — this page lives in ./fs/resctrl, stamped October 2026, and it’s literally struct rmid_read(9). bye bestie 🫶✨