xref: /openbmc/linux/Documentation/admin-guide/perf/arm_dsu_pmu.rst (revision 59809fe8)

==================================
ARM DynamIQ Shared Unit (DSU) PMU
==================================

ARM DynamIQ Shared Unit integrates one or more cores with an L3 memory system,
control logic and external interfaces to form a multicore cluster. The PMU
allows counting the various events related to the L3 cache, Snoop Control Unit
etc, using 32bit independent counters. It also provides a 64bit cycle counter.

The PMU can only be accessed via CPU system registers and are common to the
cores connected to the same DSU. Like most of the other uncore PMUs, DSU
PMU doesn't support process specific events and cannot be used in sampling mode.

The DSU provides a bitmap for a subset of implemented events via hardware
registers. There is no way for the driver to determine if the other events
are available or not. Hence the driver exposes only those events advertised
by the DSU, in "events" directory under::

  /sys/bus/event_sources/devices/arm_dsu_<N>/

The user should refer to the TRM of the product to figure out the supported events
and use the raw event code for the unlisted events.

The driver also exposes the CPUs connected to the DSU instance in "associated_cpus".


e.g usage::

	perf stat -a -e arm_dsu_0/cycles/