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arm-linux-androideabi-readelf --dyn-syms -W mylib.so
# -W: --wide , allow output width to execeed 80 chars.

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./simpleperf record --duration 4 -g -f 8000 --app com.example.your.app

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GCC compiler optimization for ARM-based systems

2017-03-03 fm4dd

The gcc compiler can optimize code by taking advantage of CPU specific features. Especially for ARM CPU's, this can have impact on application performance. ARM CPU's, even under the same architecture, could be implemented with different versions of floating point units (FPU). Utilizing full FPU potential improves performance of heavier operating systems such as full Linux distributions.

-mcpu, -march: Defining the CPU type and architecture

These flags can both be used to set the CPU type. Setting one or the other is sufficient.

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ls /sys/bus/event_source/devices/

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busybox zcat  /proc/config.gz | grep CONFIG_HW_PERF_EVENTS

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cmake ..  -DCMAKE_SYSTEM_NAME=Android -DCMAKE_SYSTEM_VERSION=18 -DCMAKE_ANDROID_ARCH_ABI=armeabi-v7a -DCMAKE_ANDROID_NDK=/ndk/android-ndk-r10e -DCMAKE_ANDROID_STL_TYPE=gnustl_static  -DCMAKE_BUILD_TYPE=Release

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[interval, segment]
1094: https://leetcode.com/problems/car-pooling/
986 : https://leetcode.com/problems/interval-list-intersections/
1109: https://leetcode.com/problems/corporate-flight-bookings/

[nth-element, priority queue, heap]
973 : https://leetcode.com/problems/k-closest-points-to-origin/

[pure dp]
1143: https://leetcode.com/problems/longest-common-subsequence/

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ssh -o ProxyCommand='nc -x 127.0.0.1:1080 %h %p' user@host 

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const static auto ioSpeedUp = [](){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    return NULL;
}();

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import socket

def get_host_ip():
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        s.connect(('8.8.8.8', 80))
        ip = s.getsockname()[0]
    finally:
        s.close()