| Qualcomm Technologies Level-2 Cache Performance Monitoring Unit (PMU) |
| ===================================================================== |
| |
| This driver supports the L2 cache clusters found in Qualcomm Technologies |
| Centriq SoCs. There are multiple physical L2 cache clusters, each with their |
| own PMU. Each cluster has one or more CPUs associated with it. |
| |
| There is one logical L2 PMU exposed, which aggregates the results from |
| the physical PMUs. |
| |
| The driver provides a description of its available events and configuration |
| options in sysfs, see /sys/devices/l2cache_0. |
| |
| The "format" directory describes the format of the events. |
| |
| Events can be envisioned as a 2-dimensional array. Each column represents |
| a group of events. There are 8 groups. Only one entry from each |
| group can be in use at a time. If multiple events from the same group |
| are specified, the conflicting events cannot be counted at the same time. |
| |
| Events are specified as 0xCCG, where CC is 2 hex digits specifying |
| the code (array row) and G specifies the group (column) 0-7. |
| |
| In addition there is a cycle counter event specified by the value 0xFE |
| which is outside the above scheme. |
| |
| The driver provides a "cpumask" sysfs attribute which contains a mask |
| consisting of one CPU per cluster which will be used to handle all the PMU |
| events on that cluster. |
| |
| Examples for use with perf: |
| |
| perf stat -e l2cache_0/config=0x001/,l2cache_0/config=0x042/ -a sleep 1 |
| |
| perf stat -e l2cache_0/config=0xfe/ -C 2 sleep 1 |
| |
| The driver does not support sampling, therefore "perf record" will |
| not work. Per-task perf sessions are not supported. |
