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[BUG] ARM big.LITTLE boards report wrong cpu count and frequency #1385

@kpyrkosz

Description

@kpyrkosz

Describe the bug
On big.LITTLE ARM systems the displayed frequency and corresponding cpu count are wrong.

System
Which OS, compiler, and compiler version are you using:

  • OS: Debian
  • Compiler and version: clang-12

To reproduce
Link a binary against libbenchmark and run it
Example output:

Running ./dojo_bench
Run on (6 X 1512 MHz CPU s)
Load Average: 0.10, 0.19, 0.77

Expected behavior
Print the highest cpu frequency of all available cores, because the benchmark is always ran there.

Running ./dojo_bench
Run on (2 X 2016 MHz CPU s and 4 X 1512 MHz CPU s)
Load Average: 0.10, 0.19, 0.77

Additional context

for i in {0..5}; do cat /sys/devices/system/cpu/cpu"$i"/cpufreq/scaling_max_freq; done
1512000
1512000
1512000
1512000
2016000
2016000

The benchmark is always ran either on cpu 4 or 5. Shutting down last 2 cores causes benchmark times to drop significantly, proving that the "1512 MHz" core is never used.

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