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| Qualcomm Datacenter Technologies L3 Cache Performance Monitoring Unit (PMU) |
| =========================================================================== |
| |
| This driver supports the L3 cache PMUs found in Qualcomm Datacenter Technologies |
| Centriq SoCs. The L3 cache on these SOCs is composed of multiple slices, shared |
| by all cores within a socket. Each slice is exposed as a separate uncore perf |
| PMU with device name l3cache_<socket>_<instance>. User space is responsible |
| for aggregating across slices. |
| |
| The driver provides a description of its available events and configuration |
| options in sysfs, see /sys/devices/l3cache*. Given that these are uncore PMUs |
| the driver also exposes a "cpumask" sysfs attribute which contains a mask |
| consisting of one CPU per socket which will be used to handle all the PMU |
| events on that socket. |
| |
| The hardware implements 32bit event counters and has a flat 8bit event space |
| exposed via the "event" format attribute. In addition to the 32bit physical |
| counters the driver supports virtual 64bit hardware counters by using hardware |
| counter chaining. This feature is exposed via the "lc" (long counter) format |
| flag. E.g.:: |
| |
| perf stat -e l3cache_0_0/read-miss,lc/ |
| |
| Given that these are uncore PMUs the driver does not support sampling, therefore |
| "perf record" will not work. Per-task perf sessions are not supported. |
