armv7 pmu

PMU access must be blocked in kernel and you must load your own kernel module or recompile linux kernel (or find precompiled kernel with perf enables) to use PMU on your machine.

ARM processor provides a Performance Monitoring Unit (PMU) as part of its architecture to enable gathering of processor execution info. Using the PMU we can track events occuring on the core via counters. We will need to configure the PMU to select events which will increment the counter.

This kernel module enable user access for Armv6 (ARM1136/56/76), ARMv7 & ARMv8 variants both in aarch32 and aarch64 mode. The module does not preconfigure pmu control register, instead expects user to configure it from user space.

The step i use as follows: 1. enable user enable by setting PMUSERENR.E bit. 2. enable pmu enable by setting PMCR.E bit and event counter and reset cycle, event counter. 3. set PMSELR and PMXEVTYPER. 4. run checksum algorithm. 5. read cpu cycle count and event counter.