How do I know，armadillo is working with openblas on my ARM？

Question

How do I know，armadillo is working with openblas on my ARM？

1. Background

   I am writing a program with armadillo, and I install openblas, and using cross compiler to compile it. I wish program with armadillo and openblas is faster than with only armadillo. But they running the same time. So, on my armv7 board ,how do I know armadillo is working with openblas?

2. Environment

   PC：ubuntu16.04 cross compiler: arm-linux-g++ borad: ARM v7

3. Compiler command:

   1. only with armadillo:

arm-linux-g++ -mtune=cortex-a7 -std=c++11 -I/home/sgks/SGKS6802_LinuxSDK/sdk_build/system/01_software/armadillo-8.100.0_install/include -L/opt/sgks/rootfs/usr/lib -L/home/sgks/SGKS6802_LinuxSDK/sdk_build/system/01_software/armadillo-8.100.0_install/lib -o ./cmake-build-debug/armadillo_test ./main.cpp -larmadillo -O3

   2. with armadillo and openblas:

arm-linux-g++ -mtune=cortex-a7 -std=c++11 -I/home/sgks/SGKS6802_LinuxSDK/sdk_build/system/01_software/armadillo-8.100.0_install/include -I/home/sgks/SGKS6802_LinuxSDK/sdk_build/system/01_software/OpenBLAS-0.2.20-install-arm/include -L/home/sgks/SGKS6802_LinuxSDK/sdk_build/system/01_software/armadillo-8.100.0_install/lib -L/home/sgks/SGKS6802_LinuxSDK/sdk_build/system/01_software/OpenBLAS-0.2.20-install-arm/lib -o ./cmake-build-debug/armadillo_test ./main.cpp -DARMA_DONT_USE_WRAPPER -lopenblas -O3

4. test code: `

   include

   include

   using namespace arma; int main() { clock_t start, stop; double dur; fmat weigth_layer1(2801, 2642,fill::randu); fmat weigth_layer2(2643, 2645, fill::randu); fmat weigth_layer3(2646, 2527, fill::randu); fmat weigth_layer4(2528, 607, fill::randu);

   fmat input(1, 2801, fill::randu);
   fmat layer1_output(1,2643);
   fmat layer2_output(1,2646);
   fmat layer3_output(1,2528);
   fmat layer4_output(1,607);
   
   //************************* layer1 *************************
   start = clock();
   layer1_output(0,span(0,2641)) = input * weigth_layer1;
   layer1_output(0,2642) = 1.0; //bias
   layer1_output.elem(find(layer1_output < 0 )) -= layer1_output.elem(find(layer1_output < 0 )); //Relu
   
   cout << "layer1: " << layer1_output.n_cols << endl;
   
   //************************* layer2 *************************
   
   layer2_output(0,span(0,2644)) = layer1_output * weigth_layer2;
   layer2_output(0,2645) = 1.0; //bias
   cout << "layer2: " << layer2_output.n_cols << endl;
   
   layer2_output.elem(find(layer2_output < 0 )) -= layer2_output.elem(find(layer2_output < 0 )); //Relu
   
   
   //************************* layer3 *************************
   
   layer3_output(0,span(0,2526)) = layer2_output * weigth_layer3;
   layer3_output(0,2527) = 1.0;
   cout << "layer3: " << layer3_output.n_cols << endl;
   
   layer3_output.elem(find(layer3_output < 0 )) -= layer3_output.elem(find(layer3_output < 0 )); //Relu
   
   //************************* layer4 *************************
   
   layer4_output = layer3_output * weigth_layer4;
   cout << "layer4: " << layer4_output.n_cols << endl;
   
   
   stop = clock();
   dur = stop - start;
   printf("time : %f\n", dur / CLOCKS_PER_SEC);
   
   return 0;
   

   }

`

PS：code format is wrong, sry for that, stackoverflow doesnt support markdown?

Answer 1

If your OpenBlas is installed correctly and the lib path is correct it should be the one used. You can view the config in Armadillo:

arma::arma_config cfg;
if( cfg.blas)
    std::cout << "BLAS enabled: "<< std::endl;

Another way to test is to disable BLAS when you compile and compare the performance (in this case it will use an emulated function). NB! Add this define before you include armadillo.

#define ARMA_DONT_USE_BLAS
#include <armadillo>

Answer 2

you can also check the armadillo library file if it is referencing openblas: for example this is my output by using the ldd command :

ldd /usr/lib/libarmadillo.so
linux-vdso.so.1 (0x0000007f9fe80000)
libblas.so.3 => /usr/lib/aarch64-linux-gnu/libblas.so.3 (0x0000007f9fdb0000)
liblapack.so.3 => /usr/lib/aarch64-linux-gnu/liblapack.so.3 (0x0000007f9f8d4000)
libarpack.so.2 => /usr/lib/aarch64-linux-gnu/libarpack.so.2 (0x0000007f9f884000)
libsuperlu.so.5 => /usr/lib/aarch64-linux-gnu/libsuperlu.so.5 (0x0000007f9f81c000)
libstdc++.so.6 => /usr/lib/aarch64-linux-gnu/libstdc++.so.6 (0x0000007f9f689000)
libm.so.6 => /lib/aarch64-linux-gnu/libm.so.6 (0x0000007f9f5cf000)
libgcc_s.so.1 => /lib/aarch64-linux-gnu/libgcc_s.so.1 (0x0000007f9f5ab000)
libc.so.6 => /lib/aarch64-linux-gnu/libc.so.6 (0x0000007f9f452000)
libopenblas.so.0 => /usr/lib/aarch64-linux-gnu/libopenblas.so.0 (0x0000007f9ed8a000)
/lib/ld-linux-aarch64.so.1 (0x0000007f9fe55000)
libgfortran.so.4 => /usr/lib/aarch64-linux-gnu/libgfortran.so.4 (0x0000007f9ec86000)
libpthread.so.0 => /lib/aarch64-linux-gnu/libpthread.so.0 (0x0000007f9ec5a000)