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report: add cgroup metrics in a separate varlink service (#41489)

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Add CpuUsage, MemoryUsage, IOReadBytes, IOReadOperations, and
TasksCurrent in a standalone socket-activated varlink service. These
metrics are gathered from the kernel via cgroup files and PID1's only
role is mapping unit names to cgroup paths — a separate process can
query PID1 once for that mapping and then read the cgroup files
directly, minimizing PID1 involvement.

The new systemd-report-cgroup-metrics service listens at
/run/systemd/report/io.systemd.CGroup and exposes:
  - io.systemd.CGroup.CpuUsage
  - io.systemd.CGroup.IOReadBytes
  - io.systemd.CGroup.IOReadOperations
  - io.systemd.CGroup.MemoryUsage (with type=current/available/peak)
  - io.systemd.CGroup.TasksCurrent

This is spun out of #41078 and based on top of it. Will rebase once
that's merged.
This commit is contained in:
Lennart Poettering
2026-04-10 12:10:06 +02:00
committed by GitHub
parent dd80e5a348 8c65fe4fa1
commit 554ba32d30
13 changed files with 760 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/core/cgroup.c
+9 -23
View File
@@ -2996,9 +2996,8 @@ int unit_check_oomd_kill(Unit *u) {
}
int unit_check_oom(Unit *u) {
_cleanup_free_ char *oom_kill = NULL;
bool increased;
uint64_t c;
uint64_t c = 0;
int r;
CGroupRuntime *crt = unit_get_cgroup_runtime(u);
@@ -3013,33 +3012,25 @@ int unit_check_oom(Unit *u) {
* back to reading oom_kill if we can't find the file or field. */
if (ctx->memory_oom_group) {
r = cg_get_keyed_attribute(
r = cg_get_keyed_attribute_uint64(
crt->cgroup_path,
"memory.events.local",
STRV_MAKE("oom_group_kill"),
&oom_kill);
"oom_group_kill",
&c);
if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
return log_unit_debug_errno(u, r, "Failed to read oom_group_kill field of memory.events.local cgroup attribute, ignoring: %m");
}
if (isempty(oom_kill)) {
r = cg_get_keyed_attribute(
if (!ctx->memory_oom_group || r < 0) {
r = cg_get_keyed_attribute_uint64(
crt->cgroup_path,
"memory.events",
STRV_MAKE("oom_kill"),
&oom_kill);
"oom_kill",
&c);
if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
return log_unit_debug_errno(u, r, "Failed to read oom_kill field of memory.events cgroup attribute: %m");
}
if (!oom_kill)
c = 0;
else {
r = safe_atou64(oom_kill, &c);
if (r < 0)
return log_unit_debug_errno(u, r, "Failed to parse memory.events cgroup oom field: %m");
}
increased = c > crt->oom_kill_last;
crt->oom_kill_last = c;
@@ -3585,14 +3576,9 @@ static int unit_get_cpu_usage_raw(const Unit *u, const CGroupRuntime *crt, nsec_
if (unit_has_host_root_cgroup(u))
return procfs_cpu_get_usage(ret);
_cleanup_free_ char *val = NULL;
uint64_t us;
r = cg_get_keyed_attribute(crt->cgroup_path, "cpu.stat", STRV_MAKE("usage_usec"), &val);
if (r < 0)
return r;
r = safe_atou64(val, &us);
r = cg_get_keyed_attribute_uint64(crt->cgroup_path, "cpu.stat", "usage_usec", &us);
if (r < 0)
return r;