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Why performance is higher on LITTLE cores?

Hi all,

I am using the HiKey970 board to run inferences on neural networks. The board comprises ARM Cortex-A73 and ARM Cortex-A53 cores.
I am using `taskset` to pin the inference process (that spawns 4 threads) once on the LITTLE cores (0-3) and once on the big cores (4-7). Contrary to what I was expecting, the inference time is almost double when running on big cores, compared to LITTLE cores.

Is there an explanation for this behavior? Are there tools that can help me understand why the threads are slower when using big cores?

To be more precise, the board is flashed with kernel version 4.9.78-147538-g244928755bbe, the code that I am using can be found in this repo.

Parents
  • Please make sure that DVFS is disabled, and the frequency of  CPUs is set a fixed value with,

    for i in 0 1 2 3; do
        echo 0 > /sys/devices/system/cpu/cpu$i/online
    done
    for i in 4 5 6 7; do
        echo 1805000 > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_max_freq
        echo 1805000 > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_min_freq
    done

Reply
  • Please make sure that DVFS is disabled, and the frequency of  CPUs is set a fixed value with,

    for i in 0 1 2 3; do
        echo 0 > /sys/devices/system/cpu/cpu$i/online
    done
    for i in 4 5 6 7; do
        echo 1805000 > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_max_freq
        echo 1805000 > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_min_freq
    done

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