google/benchmark
[BUG] ARM big.LITTLE boards report wrong cpu count and frequency
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#1.385 geöffnet am 27.04.2022
bughelp wanted
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Beschreibung
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.