| What: /sys/bus/event_source/devices/<dev>/caps |
| Date: May 2022 |
| KernelVersion: 5.19 |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> |
| 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. |
