Binnur Kurt's Blog: Java Uygulamalarından OpenCL kütüphanesine Erişim

Uzun bir süredir, geliştirdiğimiz uygulamalar çok çekirdekli sistemler üzerinde çalışıyor. Ancak uygulamaları hala sanki tek işlemcili bir sistem üzerinde çalışacakmış gibi yazıyoruz. Bu durumda çok çekirdekli yapının bilgi işleme kapasitesinden yararlanamamış oluyoruz ve uygulamamız tek bir çekirdeği kullandığı için cevap süresi yüksek kalıyor. Artık bir çok platform çok çekirdekli mimariler üzerinde uygulama geliştirmeyi kolaylaştırmak için çözümler sunuyor. Java SE 6 platformunda Concurrency API'yi kullanarak çok iş parçacıklı uygulamalar geliştirmek mümkün olsa da Java SE'deki diğer standart API'ler (örneğin Collections, Networking, Security API) çok çekirdekli mimari göz önüne alınarak gerçeklenmedikleri için yazılımın çalışma zamanındaki başarımı kısıtlı ölçüde artış göstermektedir. Bu durum Java 7'deki Fork-Join ve özellikle 2014 yılında çıkması beklenen JDK 8'deki Paralel Torbalar ve Dönüştür/İndirge çatısı ile aşılacakmış gibi görünüyor. Diğer taraftan çok çekirdekli mimariler işlemciler ile kısıtlı değiller, örneğin grafik işlemciler de çok çekirdekli mimariye sahipler. Üstelik grafik işlemcilerde genel amaçlı işlemcilere göre çok daha fazla sayıda çekirdek bulunmaktadır. Java platformunda GPU programlamayı Java 9 ile birlikte gerçekleştiriyor olabiliriz.

OpenCL kütüphanesi hem merkezi işlemci birimi hem de grafik işlemciler üzerinde işlemcinin üreticisinden, mimarisinden ve türünden bağımsız olarak uygulama geliştirmemize olanak sağlayan bir çözüm olarak öne çıkmaktadır. OpenCL Khoronos Group tarafından geliştirilmektedir. Şu an 1.2 sürümü mevcuttur. OpenCL'de temel programlama dili C'dir. Java'dan OpenCL yordamlarına Java Native Interface (JNI) aracılığı ile erişim mümkündür. Bu yazıda OpenCL yordamlarına Java sınıflarından nasıl erişilebileceği konusu anlatılmaktadır.

OpenCL kütüphanesine Java platformundan JNI ile erişeceğiz. Bunun için OpenCL platformlarının listesini ve cihaz bilgilerini almak için PlatformInfo ve DeviceInfo sınıflarını kullanacağız:
PlatformInfo.java

package com.example.opencl.utility;

import java.io.Serializable;

/**
 *
 * @author Binnur Kurt (binnur.kurt@gmail.com)
 */
public class PlatformInfo implements Serializable {

    private String platformVendor;
    private int numberOfDevices;
    private DeviceInfo[] deviceInfos;

    public PlatformInfo(String platformVendor, int numberOfDevices) {
        this.platformVendor = platformVendor;
        this.numberOfDevices = numberOfDevices;
        deviceInfos = new DeviceInfo[numberOfDevices];
    }

    public String getPlatformVendor() {
        return platformVendor;
    }

    public int getNumberOfDevices() {
        return numberOfDevices;
    }

    public DeviceInfo getDeviceInfo(int deviceNo) {
        return deviceInfos[deviceNo];
    }

    public void setDeviceInfo(int deviceNo, DeviceInfo deviceInfo) {
        this.deviceInfos[deviceNo] = deviceInfo;
    }

    public DeviceInfo[] getDeviceInfos() {
        return deviceInfos;
    }

    @Override
    public String toString() {
        return "PlatformInfo{" + "platformVendor=" + platformVendor + ", numberOfDevices=" + numberOfDevices + '}';
    }
    
}

DeviceInfo.java

package com.example.opencl.utility;

import java.io.Serializable;

/**
 *
 * @author Binnur Kurt (binnur.kurt@gmail.com)
 */
public class DeviceInfo implements Serializable {
      private int addressSize;
      private String extensions;
      private String deviceName;

    public DeviceInfo(int addressSize, String extensions, String deviceName) {
        this.addressSize = addressSize;
        this.extensions = extensions;
        this.deviceName = deviceName;
    }

    public int getAddressSize() {
        return addressSize;
    }

    public void setAddressSize(int addressSize) {
        this.addressSize = addressSize;
    }

    public String getExtensions() {
        return extensions;
    }

    public void setExtensions(String extensions) {
        this.extensions = extensions;
    }

    public String getDeviceName() {
        return deviceName;
    }

    public void setDeviceName(String deviceName) {
        this.deviceName = deviceName;
    }

    @Override
    public String toString() {
        return "DeviceInfo{" + "deviceName=" + deviceName + ", addressSize=" + addressSize + ", \nextensions=" + extensions + "\n}";
    }
      
}

OpenCL ile bağlantıyı aşağıda verilen OpenCLUtility sınıfı ile kuracağız:

package com.example.opencl.utility;

import com.example.domain.Element;

/**
 *
 * @author Binnur Kurt (binnur.kurt@gmail.com)
 */
public class OpenCLUtility {
      public native PlatformInfo[] getPlatformInfo();
      public native void execute(Element[] array);
      static {
         System.loadLibrary("myopencllib"); 
      }    
}

JNI için gerekli C++ başlık dosyasını aşağıdaki komutu kullanarak üretiyoruz:

javah -jni -o OpenCLUtility.h com.example.opencl.utility.OpenCLUtility

OpenCLUtility.h

#include <jni.h>
/* Header for class com_example_opencl_utility_OpenCLUtility */

#ifndef _Included_com_example_opencl_utility_OpenCLUtility
#define _Included_com_example_opencl_utility_OpenCLUtility
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_example_opencl_utility_OpenCLUtility
 * Method:    getPlatformInfo
 * Signature: ()[Lcom/example/opencl/utility/PlatformInfo;
 */
JNIEXPORT jobjectArray JNICALL Java_com_example_opencl_utility_OpenCLUtility_getPlatformInfo
  (JNIEnv *, jobject);

/*
 * Class:     com_example_opencl_utility_OpenCLUtility
 * Method:    execute
 * Signature: ([Lcom/example/domain/Element;)V
 */
JNIEXPORT void JNICALL Java_com_example_opencl_utility_OpenCLUtility_execute
  (JNIEnv *, jobject, jobjectArray);

#ifdef __cplusplus
}
#endif
#endif

OpenCLUtility.cpp:

#include "OpenCLUtility.h"

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>

#include <CL/cl.h>

#define LOCAL_SIZE 512

cl_mem  g_inputBuffer = NULL;
cl_context g_context = NULL;
cl_command_queue g_cmd_queue = NULL;
cl_program g_program = NULL;
cl_kernel g_kernel = NULL;

#include "OpenCLUtil.h"

//for perf. counters
#include <Windows.h>

LARGE_INTEGER g_PerfFrequency;
LARGE_INTEGER g_PerformanceCountNDRangeStart;
LARGE_INTEGER g_PerformanceCountNDRangeStop;

struct JobInfo {
    char* companyName;
    char* companyAddress;
    char* telNumber;
    char* faxNumber;
} ;

typedef struct JobInfo TJobInfo;
typedef struct JobInfo* PJobInfo;

struct Element {
    int id;
    int identityCardNo;
    char* name;
    char* surname;
    int age;
    TJobInfo jobInfo;
    char* email;
    bool selected;
    bool masked;
} ;

typedef struct Element TElement;
typedef struct Element* PElement;

JNIEXPORT jobjectArray JNICALL Java_com_example_opencl_utility_OpenCLUtility_getPlatformInfo
(JNIEnv *env, jobject obj){
      
 /* Host/device data structures */
 cl_platform_id *platforms;
 cl_uint numberOfPlatformsAvailable;
 cl_device_id *devices;
 cl_uint num_devices, addr_data;
 cl_int i,j, err;

 /* Extension data */
 char name_data[48], ext_data[4096];
 char platform_vendor[2][40]; 

 /* Identify a platform */
 err = clGetPlatformIDs(10, NULL, &numberOfPlatformsAvailable);   
 if (err < 0) {   
    perror("Error: Couldn't find any platforms");
    exit(1);
 }
 platforms= (cl_platform_id*)malloc(sizeof(cl_platform_id)*numberOfPlatformsAvailable);
 err = clGetPlatformIDs(numberOfPlatformsAvailable, platforms, NULL);   
 if (err < 0) {   
       perror("Couldn't find any platforms");
      exit(1);
 }
 printf("There are %d platforms available in the system.\n",numberOfPlatformsAvailable);
 /*
        Create the result array of PlatformInfo
 */
 jclass platformInfoClass= env->FindClass("com/example/opencl/utility/PlatformInfo");
        jclass deviceInfoClass= env->FindClass("com/example/opencl/utility/DeviceInfo");
        jmethodID platformInfoClassConstructorId= env->GetMethodID(platformInfoClass,"<init>","(Ljava/lang/String;I)V");
        jmethodID deviceInfoClassConstructorId= env->GetMethodID(deviceInfoClass,"<init>","(ILjava/lang/String;Ljava/lang/String;)V");
        jmethodID platformInfoSetDeviceInfoId= env->GetMethodID(platformInfoClass,"setDeviceInfo","(ILcom/example/opencl/utility/DeviceInfo;)V");

        //jobjectArray result= env->NewObjectArray(platformInfoClass,platformInfoClassConstructorId,vendorName,numberOfPlatformsAvailable);
        jobjectArray result= env->NewObjectArray(numberOfPlatformsAvailable,platformInfoClass,NULL);
       
 for (j=0;j<numberOfPlatformsAvailable;++j){
      /* Determine number of connected devices */
      err = clGetDeviceIDs(platforms[j], CL_DEVICE_TYPE_ALL, 1, NULL, &num_devices);    
      if(err < 0) {    
     perror("Error: Couldn't find any devices.");
    exit(1);
      }
             clGetPlatformInfo(platforms[j],CL_PLATFORM_VENDOR,sizeof(platform_vendor),&platform_vendor[j],NULL);
     // Access connected devices
     devices = (cl_device_id*) malloc(sizeof(cl_device_id) * num_devices);  
     clGetDeviceIDs(platforms[j], CL_DEVICE_TYPE_ALL,num_devices, devices, NULL);    

     // Create PlatformInfo and set to the result array
     jstring  vendorName= env->NewStringUTF(platform_vendor[j]);
          jobject platformObject= env->NewObject(platformInfoClass,platformInfoClassConstructorId,vendorName,num_devices);
     env->SetObjectArrayElement(result,j,platformObject);  

     // Obtain data for each connected device
     for (i=0; i<num_devices; i++) {
        
     err = clGetDeviceInfo(devices[i], CL_DEVICE_NAME,sizeof(name_data), name_data, NULL);   
     if (err < 0) {  
      perror("Error: Couldn't read extension data.");
     exit(1);
     }
     clGetDeviceInfo(devices[i], CL_DEVICE_ADDRESS_BITS,sizeof(ext_data), &addr_data, NULL);   
     clGetDeviceInfo(devices[i], CL_DEVICE_EXTENSIONS, sizeof(ext_data), ext_data, NULL);   
     // create device info and set it to the platform
     jstring extensions= env->NewStringUTF(ext_data);
     jstring deviceName= env->NewStringUTF(name_data);
     jobject deviceObject= env->NewObject(deviceInfoClass,deviceInfoClassConstructorId,addr_data,extensions,deviceName);
              env->CallDoubleMethod(platformObject,platformInfoSetDeviceInfoId,i,deviceObject);
     }       
     free(devices);
    }       
    // free data structures
    free(platforms);
    return result;
}

char* jstringToCString(JNIEnv *env,jstring msg){
   const char* cstringTemp;
   cstringTemp= env->GetStringUTFChars(msg,NULL);
   int len= env->GetStringLength(msg)+1;
   char *resCString= (char*)malloc(sizeof(char)*len);
   strcpy(resCString,cstringTemp);
   *(resCString+len-1)='\0';
   env->ReleaseStringUTFChars(msg,cstringTemp);
   return resCString;
}

char* jstringToCStringV2(JNIEnv *env,jstring msg){
   return const_cast<char*>(env->GetStringUTFChars(msg,NULL));
}

void JniConvertToNativeArrayToElementArray(JNIEnv *env, jobject *obj, PElement nativeArray,jobjectArray *arr){
   int arraySize= env->GetArrayLength(*arr);
   jclass elementClass= env->FindClass("com/example/domain/Element");
   jclass javaUtilListClass= env->FindClass ("Ljava/util/ArrayList;");
   jclass jobInfoClass= env->FindClass("com/example/model/JobInfo");
   // Field IDs
   jfieldID idFieldID= env->GetFieldID(elementClass,"id","I");
   jfieldID ageFieldID= env->GetFieldID(elementClass,"age","I");
   jfieldID identityCardNoFieldID= env->GetFieldID(elementClass,"identityCardNo","I");

      for (int i=0;i<arraySize;++i){
       jobject jniArrayElement= env->GetObjectArrayElement(*arr,i);             
       env->SetIntField(jniArrayElement,ageFieldID,nativeArray[i].age);
       env->SetIntField(jniArrayElement,identityCardNoFieldID,nativeArray[i].identityCardNo);
       env->SetIntField(jniArrayElement,idFieldID,nativeArray[i].id);    
      }
}

PElement JniConvertElementArrayToNative(JNIEnv *env, jobject *obj, jobjectArray *arr){
   int arraySize= env->GetArrayLength(*arr);
   PElement nativeArray= (PElement) malloc(sizeof(TElement) * arraySize);
   jclass elementClass= env->FindClass("com/example/domain/Element");
   jclass javaUtilListClass= env->FindClass ("Ljava/util/ArrayList;");
   jclass jobInfoClass= env->FindClass("com/example/model/JobInfo");
   // Field IDs
      jfieldID idFieldID= env->GetFieldID(elementClass,"id","I");
      jfieldID ageFieldID= env->GetFieldID(elementClass,"age","I");
      jfieldID nameFieldID= env->GetFieldID(elementClass,"name","Ljava/lang/String;");
      jfieldID surnameFieldID= env->GetFieldID(elementClass,"surname","Ljava/lang/String;");
   jfieldID emailFieldID= env->GetFieldID(elementClass,"email","Ljava/lang/String;");
      jfieldID identityCardNoFieldID= env->GetFieldID(elementClass,"identityCardNo","I");
      jfieldID jobInfoFieldID= env->GetFieldID(elementClass,"jobInfo","Lcom/example/model/JobInfo;");
      jfieldID companyNameFieldID= env->GetFieldID(jobInfoClass,"companyName","Ljava/lang/String;"); 
      jfieldID companyAddressFieldID= env->GetFieldID(jobInfoClass,"companyAddress","Ljava/lang/String;");
      jfieldID telNumberFieldID= env->GetFieldID(jobInfoClass,"telNumber","Ljava/lang/String;");
      jfieldID faxNumberFieldID= env->GetFieldID(jobInfoClass,"faxNumber","Ljava/lang/String;");
      // Local fields
      jstring jstringName;
      jstring jstringSurname;
      jstring jstringEmail;
      jstring jstringCompanyName;
      jstring jstringCompanyAddress;
      jobject jobInfo;
      jstring telNumber;
      jstring faxNumber;
      int listSize;

   for (int i=0;i<arraySize;++i){
    jobject jniArrayElement= env->GetObjectArrayElement(*arr,i);          
       nativeArray[i].age= (jint) env->GetIntField(jniArrayElement,ageFieldID);
       nativeArray[i].id= (jint) env->GetIntField(jniArrayElement,idFieldID);    
       nativeArray[i].identityCardNo= (jint) env->GetIntField(jniArrayElement,identityCardNoFieldID);
    jstringName= (jstring) env->GetObjectField(jniArrayElement,nameFieldID);
    jstringSurname= (jstring) env->GetObjectField(jniArrayElement,surnameFieldID);
    jstringEmail= (jstring) env->GetObjectField(jniArrayElement,emailFieldID);    
    jobInfo= env->GetObjectField(jniArrayElement,jobInfoFieldID);
    nativeArray[i].name= jstringToCString(env,jstringName);
    nativeArray[i].surname= jstringToCString(env,jstringSurname);      
        nativeArray[i].email= jstringToCString(env,jstringEmail);
    // .jobInfo
    jobInfo= env->GetObjectField(jniArrayElement,jobInfoFieldID);
       // .companyName
             jstringCompanyName= (jstring) env->GetObjectField(jobInfo,companyNameFieldID);
             nativeArray[i].jobInfo.companyName = jstringToCStringV2(env,jstringCompanyName);
       // .companyName
             jstringCompanyAddress= (jstring) env->GetObjectField(jobInfo,companyAddressFieldID);
             nativeArray[i].jobInfo.companyAddress = jstringToCStringV2(env,jstringCompanyAddress);
             // telNumber
             telNumber= (jstring) env->GetObjectField(jobInfo,telNumberFieldID);  
             nativeArray[i].jobInfo.telNumber = jstringToCStringV2(env,telNumber);
             // faxNumber
             faxNumber= (jstring) env->GetObjectField(jobInfo,faxNumberFieldID);
       nativeArray[i].jobInfo.faxNumber = jstringToCStringV2(env,faxNumber);
   }
   return nativeArray;
}

JNIEXPORT void JNICALL Java_com_example_opencl_utility_OpenCLUtility_execute(JNIEnv *env, jobject obj, jobjectArray arr){
      cl_int err = CL_SUCCESS;
   int arraySize= env->GetArrayLength(arr);
   arraySize=arraySize-arraySize%8;
   printf("INFO: Recieved array of size %d\n",arraySize);  

   PElement inputArray= JniConvertElementArrayToNative(env,&obj,&arr);

   if(Setup_OpenCL("SampleFilter.cl")==-1){
        printf("ERROR: Failed to Setup OpenCL...\n");
        return;      
   }
      // allocate the buffer
      g_inputBuffer = clCreateBuffer(g_context, CL_MEM_READ_WRITE | CL_MEM_USE_HOST_PTR, sizeof(TListElement) * arraySize, inputArray, NULL);

      if (g_inputBuffer == (cl_mem)0){
        printf("ERROR: Failed to create Input Buffer...\n");
        return;
      }
      printf("INFO: g_inputBuffer is created (%x)...\n",g_inputBuffer);
      err  =  clSetKernelArg(g_kernel, 0, sizeof(cl_mem), (void *) &g_inputBuffer);
      if (err != CL_SUCCESS) {
        printf("ERROR: Failed to set input g_kernel arguments...\n");
        return;
      }
      printf("INFO: g_kernel parameters are set...\n");

   size_t global_work_size[1] = { arraySize };
      size_t local_work_size[1]= { LOCAL_SIZE };     
   size_t offset[1]= { 0 };     

      QueryPerformanceCounter(&g_PerformanceCountNDRangeStart);

      // execute kernel
      if (CL_SUCCESS != (err = clEnqueueNDRangeKernel(g_cmd_queue, g_kernel, 1, offset, global_work_size, local_work_size, 0, NULL, NULL))){
        printf("ERROR: Failed to run kernel...\n");
        return;
      }
      err = clFinish(g_cmd_queue);
      QueryPerformanceCounter(&g_PerformanceCountNDRangeStop);

   void* tmp_ptr = NULL;
      tmp_ptr = clEnqueueMapBuffer(g_cmd_queue, g_inputBuffer, true, CL_MAP_READ, 0, sizeof(struct ListElement) * arraySize, 0, NULL, NULL, NULL);
   if (tmp_ptr!=inputArray){
      printf("ERROR: clEnqueueMapBuffer failed to return original pointer\n");
       return;
   }

    err = clFinish(g_cmd_queue);
    clEnqueueUnmapMemObject(g_cmd_queue, g_inputBuffer, tmp_ptr, 0, NULL, NULL);
    clReleaseMemObject(g_inputBuffer); 

    //retrieve perf. counter frequency
    QueryPerformanceFrequency(&g_PerfFrequency);
    printf("NDRange perf. counter time %f ms.\n", 
        1000.0f*(float)(g_PerformanceCountNDRangeStop.QuadPart - g_PerformanceCountNDRangeStart.QuadPart)/(float)g_PerfFrequency.QuadPart);
    JniConvertToNativeArrayToElementArray(env,&obj,inputArray,&arr);
   free(inputArray);
   g_inputBuffer = NULL;
}

Bu kodu Windows işletim sisteminde derleyebilmek için aşağıdaki komutu kullanıyoruz:
compile.bat:
cl -EHsc "-I%JAVA_HOME%\include" "-I%JAVA_HOME%\include\win32" "-I%INTELOCLSDKROOT%\include" -LD %1 OpenCL.lib -Fe%2 /link /LIBPATH:"%INTELOCLSDKROOT%\lib\x86" OpenCL.lib
build_dll.bat:
call setenv.bat
IF NOT EXIST myopencllib.dll call compile.bat OpenCLUtility.cpp myopencllib.dll
cmd> build_dll.bat
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.21022.08 for 80x86
Copyright (C) Microsoft Corporation. All rights reserved.

OpenCLUtility.cpp
Microsoft (R) Incremental Linker Version 9.00.21022.08
Copyright (C) Microsoft Corporation. All rights reserved.

/dll
/implib:myopencllib.lib
/out:myopencllib.dll
"/LIBPATH:C:\Program Files (x86)\Intel\OpenCL SDK\2.0\lib\x86"
OpenCL.lib
OpenCLUtility.obj
OpenCL.lib

Creating library myopencllib.lib and object myopencllib.exp

Çekirdek fonksiyonu olarak aşağıdaki SampleFilter.cl dosyası içindeki __kernel void SampleFilter(__global struct Element* pSrc) fonksiyonunu kullancağız:

struct JobInfo {
    char* companyName;
    char* companyAddress;
    char* telNumber;
    char* faxNumber;
} ;

typedef struct JobInfo TJobInfo;

struct Element {
    int id;
    int identityCardNo;
    char* name;
    char* surname;
    int age;
    TJobInfo jobInfo;
    char* email;
    bool selected;
    bool masked;
} ;

__kernel void SampleFilter(__global struct Element* pSrc)
{
 const int x = get_global_id(0); 
 const int size = get_local_size(0); 
    pSrc[x].id=pSrc[x].id+5;
    pSrc[x].identityCardNo=pSrc[x].identityCardNo+1000;
    pSrc[x].age=pSrc[x].age+10;
}

Projenin tamamını betiklerle beraber bu adresten indirebilirsiniz.

Binnur Kurt's Blog

Wednesday, July 31, 2013

Java Uygulamalarından OpenCL kütüphanesine Erişim

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