LIKWID

Count one callback invocation with the explicit PerfCheckerLIKWID companion. First prepare its worker project using Prepare the explicit worker below, then start Julia in that project. The companion does not change kernel permissions or affinity.

using PerfChecker, PerfCheckerLIKWID
# Pick the first CPU inside the current inherited Linux affinity, without repinning.
line = only(filter(l -> startswith(l, "Cpus_allowed_list:"),
    split(read("/proc/self/status", String), '\n')))
cpu = parse(Int, first(split(first(split(strip(split(line, ':')[2]), ',')), '-')))
called = Ref(false)
result = measure_counters(;
    event_set="INSTR_RETIRED_ANY:FIXC0,CPU_CLK_UNHALTED_CORE:FIXC1",
    cpuids=[cpu], units=Dict("INSTR_RETIRED_ANY"=>"1", "CPU_CLK_UNHALTED_CORE"=>"1")) do
    called[] = true
    sum(1:10000)
end
println((result.status, result.reason, called[], length(result.records)))

Observed output: (:unavailable, "library_unavailable", false, 0). The host lacks liblikwid; the receipt records the real refusal, selected CPU and resolved versions. No callback ran. A permitted native installation is required for positive hardware evidence; count units are explicit and backend access mode determines attribution.

Prepare the explicit worker

PerfCheckerLIKWID 1.0.1 is registered in General. Use a separate worker project:

using Pkg
Pkg.activate("perf/likwid-worker")
Pkg.add(["PerfChecker", "PerfCheckerLIKWID"])
Pkg.add(Pkg.PackageSpec(name="LIKWID", version="0.4.6"))

Start Julia with --project=perf/likwid-worker for the callback above. Install your measured target in that worker project separately. LIKWID 0.4.6 requires PrettyTables 3; the other companion requires PrettyTables 2. Native liblikwid and permitted CPU counter access must already exist. Choose exact event/counter pairs supported by your hardware and CPUs inside inherited affinity; group aliases and automatic repinning are refused. Published Core has a known ARM import limitation.

Collection window

The suite integration runs operation and synchronization once, then stops counters before the oracle. It has no implicit warmup. LinuxPerf counts the calling OS thread's user-space execution, excluding other threads/processes; enabled/running times are separate nanosecond values. LIKWID measures selected CPUs within inherited affinity; access mode and PID configuration determine attribution and direct/daemon modes may include unrelated activity. LIKWID group time is in seconds; raw event units are explicit. Counts and CPU cycles use unit 1, not seconds. An unavailable result is missing evidence. LinuxPerf's counter_not_scheduled refusal can occur after the operation, so inspect its lifecycle before retrying.

Use run_counter_suite or an explicit counter_executor in a Julia suite runner. Default CLI, VS Code, Pluto and MCP selectors do not offer these companions.