Performance Evaluation Library Using Linux perf for ARM Processors

Introduction

The perf_helper library is designed for performance measurement using perf.

• PMU driver: armv8_pmuv3_0
• Compilers:
  • GCC
  • GFORTRAN

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Adding Section Measurements

To measure performance within specific sections of your code:

1. Use perf_initialize and perf_finalize outside parallel regions.
2. Use perf_start_section and perf_stop_section within parallel regions.
3. Specify the events to measure using the PERF_EVENTS environment variable.

Note: Section IDs range from 0 to 99, and nested sections are supported.

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Code Examples

C

#include "perf_helper.h"
void compute(int n, double x);

int main() {
    int n = 1000000;
    double x;

    perf_initialize();
    #pragma omp parallel
    {
        perf_start_section(0);
        perf_start_section(1);
        compute(n, x);
        perf_stop_section(1);
        perf_start_section(2);
        compute(n, x);
        perf_stop_section(2);
        perf_stop_section(0);
    }
    perf_finalize();
}

Fortran90

program main
  use perf_helper_mod
  implicit none
  integer, parameter :: n = 1000000
  double precision :: x
  integer :: i

  call perf_initialize()
  !$omp parallel
  call perf_start_section(0)
  do i = 1, 10
    ! Section 1
    call perf_start_section(1)
    call sample(n, x)
    call perf_stop_section(1)
    ! Section 2
    call perf_start_section(2)
    call sample(n, x)
    call perf_stop_section(2)
  end do
  call perf_stop_section(0)
  !$omp end parallel
  call perf_finalize()
end program main

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Compilation

For GCC

#!/bin/sh
gcc -fopenmp -c main.c -o main.o
gcc -fopenmp -c test.c -o test.o
gcc -fopenmp main.o test.o -lperf_helper

For Fortran90

#!/bin/sh
gfortran -fopenmp -c main.f90 -o main.o
gfortran -fopenmp -c test.f90 -o test.o
gfortran -fopenmp main.o test.o -lperf_helper

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Execution

1. Define performance events:

   export PERF_EVENTS="INST_SPEC,CPU_CYCLES,STALL_FRONTEND,STALL_BACKEND"

2. Run the executable:

   ./a.out