Performance Monitors Count Enable Set register: clear bit 0*/Īsm volatile("msr pmcntenset_el0, %0" : : "r" (r&0xfffffffe)) * Performance Monitors Count Enable Set register bit 30:1 disable, 31,1 enable */Īsm volatile("mrs %0, pmcntenset_el0" : "=r" (r)) Īsm volatile("msr pmcntenset_el0, %0" : : "r" (r|1)) Īsm volatile("mrs %0, pmevcntr0_el0" : "=r" (r)) * Setup PMU counter to record specific event */ĮvtCount &= ARMV8_PMEVTYPER_EVTCOUNT_MASK Īsm volatile("msr pmevtyper0_el0, %0" : : "r" (evtCount)) Below is the code to set PMU register PMUSERENR_EL0 to enable user-mode access.Īsm volatile("mrs %0, pmccntr_el0" : "=r" (r)) So the first thing is to create a kernel module to enable user-mode access to PMU counters.
#LINUX PINTA PERFORMANCE MANUAL#
Please refer to ARMv8 Architecture Reference Manual for details. (This article will not cover all register detail. Please note that ARMv8-A architecture allows access PMU counters from EL0(means in user space of Linux). The basic way is write assembly code to access PMU registers directly. Access PMU registers by assembly code directly.This article will try to cover ARMv8’s PMU.
#LINUX PINTA PERFORMANCE HOW TO#
But if only a piece of code is interested in debugging, how to monitoring the CPU performance event counters for it? There are some articles describe how to make it for ARMv7.
Perf can be used when measure the whole software program. For detailed usage of perf utility, refer to perf wiki tutorial page. All other events related to specific CPU architecture can only be accessed by using raw event id.
Due to the difference architecture of CPUs, only a few events are common defined in kernel. Perf supports raw event id or named event. Kernel has a utility named perf to view CPU PMU event statistics. Performance counters support has been added in Linux Kernel since 3.6. We can get processor status, like cycle, instruction executed, branch taken, cache miss/hit, memory read/write, etc from these PMU event counters. Performance Monitor in ARMv8-A includes a 64-bit cycle counter, a number of 32-bit event counters and control component.įrom programmer perspective, it is a handy tool for performance monitoring and tuning. Performance Monitor is an optional feature in ARMv8-A architecture.
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