StarFive StarLink Performance Monitor Unit (PMU)

StarFive StarLink Performance Monitor Unit (PMU) exists within the StarLink Coherent Network on Chip (CNoC) that connects multiple CPU clusters with an L3 memory system.

The uncore PMU supports overflow interrupt, up to 16 programmable 64bit event counters, and an independent 64bit cycle counter. The PMU can only be accessed via Memory Mapped I/O and are common to the cores connected to the same PMU.

Driver exposes supported PMU events in sysfs “events” directory under:

/sys/bus/event_source/devices/starfive_starlink_pmu/events/

Driver exposes cpu used to handle PMU events in sysfs “cpumask” directory under:

/sys/bus/event_source/devices/starfive_starlink_pmu/cpumask/

Driver describes the format of config (event ID) in sysfs “format” directory under:

/sys/bus/event_source/devices/starfive_starlink_pmu/format/

Example of perf usage:

$ perf list

starfive_starlink_pmu/cycles/                      [Kernel PMU event]
starfive_starlink_pmu/read_hit/                    [Kernel PMU event]
starfive_starlink_pmu/read_miss/                   [Kernel PMU event]
starfive_starlink_pmu/read_request/                [Kernel PMU event]
starfive_starlink_pmu/release_request/             [Kernel PMU event]
starfive_starlink_pmu/write_hit/                   [Kernel PMU event]
starfive_starlink_pmu/write_miss/                  [Kernel PMU event]
starfive_starlink_pmu/write_request/               [Kernel PMU event]
starfive_starlink_pmu/writeback/                   [Kernel PMU event]


$ perf stat -a -e /starfive_starlink_pmu/cycles/ sleep 1

Sampling is not supported. As a result, “perf record” is not supported. Attaching to a task is not supported, only system-wide counting is supported.