What: /sys/bus/event_source/devices/<dev>/caps
Date: May 2022
KernelVersion: 5.19
Contact: Linux kernel mailing list <[email protected]>
Description:
Attribute group to describe the capabilities exposed
for a particular pmu. Each attribute of this group can
expose information specific to a PMU, say pmu_name, so that
userspace can understand some of the feature which the
platform specific PMU supports.
One of the example available capability in supported platform
like Intel is pmu_name, which exposes underlying CPU name known
to the PMU driver.
Example output in powerpc:
grep . /sys/bus/event_source/devices/cpu/caps/*
/sys/bus/event_source/devices/cpu/caps/pmu_name:POWER9
The "branch_counter_nr" in the supported platform exposes the
maximum number of counters which can be shown in the u64 counters
of PERF_SAMPLE_BRANCH_COUNTERS, while the "branch_counter_width"
exposes the width of each counter. Both of them can be used by
the perf tool to parse the logged counters in each branch.
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