180 lines
6.3 KiB
Markdown
180 lines
6.3 KiB
Markdown
## Compile the library
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### Normal compile
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* type `make` to detect the CPU automatically.
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or
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* type `make TARGET=xxx` to set target CPU, e.g. `make TARGET=NEHALEM`. The full target list is in file TargetList.txt.
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### Cross compile
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Please set `CC` and `FC` with the cross toolchains. Then, set `HOSTCC` with your host C compiler. At last, set `TARGET` explicitly.
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Examples:
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* On x86 box, compile the library for ARM Cortex-A9 linux.
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Install only gnueabihf versions. Please check https://github.com/xianyi/OpenBLAS/issues/936#issuecomment-237596847
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make CC=arm-linux-gnueabihf-gcc FC=arm-linux-gnueabihf-gfortran HOSTCC=gcc TARGET=CORTEXA9
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* On X86 box, compile this library for loongson3a CPU.
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```
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make BINARY=64 CC=mips64el-unknown-linux-gnu-gcc FC=mips64el-unknown-linux-gnu-gfortran HOSTCC=gcc TARGET=LOONGSON3A
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```
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* On X86 box, compile this library for loongson3a CPU with loongcc (based on Open64) compiler.
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```
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make CC=loongcc FC=loongf95 HOSTCC=gcc TARGET=LOONGSON3A CROSS=1 CROSS_SUFFIX=mips64el-st-linux-gnu- NO_LAPACKE=1 NO_SHARED=1 BINARY=32
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```
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### Debug version
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make DEBUG=1
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### Install to the directory (optional)
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Example:
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make install PREFIX=your_installation_directory
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The default directory is /opt/OpenBLAS. Note that any flags passed to `make` during build should also be passed to `make install` to circumvent any install errors, i.e. some headers not being copied over correctly.
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For more information, please read [Installation Guide](install.md).
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## Link the library
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* Link shared library
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```
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gcc -o test test.c -I/your_path/OpenBLAS/include/ -L/your_path/OpenBLAS/lib -Wl,-rpath,/your_path/OpenBLAS/lib -lopenblas
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```
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The `-Wl,-rpath,/your_path/OpenBLAS/lib` option to linker can be omitted if you ran `ldconfig` to update linker cache, put `/your_path/OpenBLAS/lib` in `/etc/ld.so.conf` or a file in `/etc/ld.so.conf.d`, or installed OpenBLAS in a location that is part of the `ld.so` default search path (usually /lib,/usr/lib and /usr/local/lib). Alternatively, you can set the environment variable LD_LIBRARY_PATH to point to the folder that contains libopenblas.so. Otherwise, linking at runtime will fail with a message like `cannot open shared object file: no such file or directory`
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If the library is multithreaded, please add `-lpthread`. If the library contains LAPACK functions, please add `-lgfortran` or other Fortran libs, although if you only make calls to LAPACKE routines, i.e. your code has `#include "lapacke.h"` and makes calls to methods like `LAPACKE_dgeqrf`, `-lgfortran` is not needed.
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* Link static library
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```
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gcc -o test test.c /your/path/libopenblas.a
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```
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You can download `test.c` from https://gist.github.com/xianyi/5780018
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## Code examples
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### Call CBLAS interface
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This example shows calling cblas_dgemm in C. https://gist.github.com/xianyi/6930656
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```c
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#include <cblas.h>
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#include <stdio.h>
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void main()
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{
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int i=0;
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double A[6] = {1.0,2.0,1.0,-3.0,4.0,-1.0};
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double B[6] = {1.0,2.0,1.0,-3.0,4.0,-1.0};
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double C[9] = {.5,.5,.5,.5,.5,.5,.5,.5,.5};
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cblas_dgemm(CblasColMajor, CblasNoTrans, CblasTrans,3,3,2,1,A, 3, B, 3,2,C,3);
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for(i=0; i<9; i++)
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printf("%lf ", C[i]);
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printf("\n");
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}
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```
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```
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gcc -o test_cblas_open test_cblas_dgemm.c -I /your_path/OpenBLAS/include/ -L/your_path/OpenBLAS/lib -lopenblas -lpthread -lgfortran
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```
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### Call BLAS Fortran interface
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This example shows calling dgemm Fortran interface in C. https://gist.github.com/xianyi/5780018
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```c
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#include "stdio.h"
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#include "stdlib.h"
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#include "sys/time.h"
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#include "time.h"
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extern void dgemm_(char*, char*, int*, int*,int*, double*, double*, int*, double*, int*, double*, double*, int*);
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int main(int argc, char* argv[])
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{
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int i;
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printf("test!\n");
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if(argc<4){
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printf("Input Error\n");
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return 1;
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}
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int m = atoi(argv[1]);
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int n = atoi(argv[2]);
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int k = atoi(argv[3]);
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int sizeofa = m * k;
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int sizeofb = k * n;
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int sizeofc = m * n;
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char ta = 'N';
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char tb = 'N';
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double alpha = 1.2;
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double beta = 0.001;
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struct timeval start,finish;
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double duration;
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double* A = (double*)malloc(sizeof(double) * sizeofa);
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double* B = (double*)malloc(sizeof(double) * sizeofb);
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double* C = (double*)malloc(sizeof(double) * sizeofc);
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srand((unsigned)time(NULL));
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for (i=0; i<sizeofa; i++)
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A[i] = i%3+1;//(rand()%100)/10.0;
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for (i=0; i<sizeofb; i++)
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B[i] = i%3+1;//(rand()%100)/10.0;
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for (i=0; i<sizeofc; i++)
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C[i] = i%3+1;//(rand()%100)/10.0;
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//#if 0
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printf("m=%d,n=%d,k=%d,alpha=%lf,beta=%lf,sizeofc=%d\n",m,n,k,alpha,beta,sizeofc);
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gettimeofday(&start, NULL);
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dgemm_(&ta, &tb, &m, &n, &k, &alpha, A, &m, B, &k, &beta, C, &m);
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gettimeofday(&finish, NULL);
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duration = ((double)(finish.tv_sec-start.tv_sec)*1000000 + (double)(finish.tv_usec-start.tv_usec)) / 1000000;
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double gflops = 2.0 * m *n*k;
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gflops = gflops/duration*1.0e-6;
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FILE *fp;
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fp = fopen("timeDGEMM.txt", "a");
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fprintf(fp, "%dx%dx%d\t%lf s\t%lf MFLOPS\n", m, n, k, duration, gflops);
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fclose(fp);
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free(A);
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free(B);
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free(C);
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return 0;
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}
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```
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```
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gcc -o time_dgemm time_dgemm.c /your/path/libopenblas.a -lpthread
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./time_dgemm <m> <n> <k>
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```
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## Troubleshooting
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* Please read [Faq](faq.md) at first.
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* Please use gcc version 4.6 and above to compile Sandy Bridge AVX kernels on Linux/MingW/BSD.
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* Please use Clang version 3.1 and above to compile the library on Sandy Bridge microarchitecture. The Clang 3.0 will generate the wrong AVX binary code.
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* The number of CPUs/Cores should less than or equal to 256. On Linux x86_64(amd64), there is experimental support for up to 1024 CPUs/Cores and 128 numa nodes if you build the library with BIGNUMA=1.
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* OpenBLAS does not set processor affinity by default. On Linux, you can enable processor affinity by commenting the line NO_AFFINITY=1 in Makefile.rule. But this may cause [the conflict with R parallel](https://stat.ethz.ch/pipermail/r-sig-hpc/2012-April/001348.html).
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* On Loongson 3A. make test would be failed because of pthread_create error. The error code is EAGAIN. However, it will be OK when you run the same testcase on shell.
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## BLAS reference manual
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If you want to understand every BLAS function and definition, please read [Intel MKL reference manual](https://software.intel.com/en-us/intel-mkl/documentation) or [netlib.org](http://netlib.org/blas/)
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Here are [OpenBLAS extension functions](extensions.md)
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