Jocl 和设备裂变

Question

编辑：问题解决了！ rzymek 的回答很有帮助。

问题：对于 JOCL，如何通过设备裂变从 opencl 计算中排除一些 CPU 内核？（cl_device_partition_property 的 Java 端口在 0.1.9 版本中似乎已损坏）

编辑：我发现了这个：

clCreateSubDevices(devices[0][1],core , 1, cpuCores, coreIDs);

但是 java/jocl 不接受这个：

cl_device_partition_property core=CL.CL_DEVICE_PARTITION_BY_COUNTS;

错误是：

Type mismatch: cannot convert from int to cl_device_partition_property

刚刚尝试空初始化，然后使用变量自己的方法来设置属性：

    cl_device_partition_property core = null;
    core.addProperty(CL_DEVICE_PARTITION_BY_COUNTS, platforms[0]);

编辑：现在它给出了

    java.lang.NullPointerException,

错误。

IT 需要是 unsigned int（不是 cl_device_partition_property），但 java 没有。

构造函数的新尝试：

cl_device_partition_property core = new cl_device_partition_property();

错误：

 A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000007fedb6500bf, pid=4952, tid=4852
#
# JRE version: 7.0_21-b11
# Java VM: Java HotSpot(TM) 64-Bit Server VM (23.21-b01 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C  [amdocl64.dll+0x1800bf]  clGetSamplerInfo+0x1972f
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of     Windows
#
# An error report file with more information is saved as:
# C:\javalar\buraya\paralelProje\hs_err_pid4952.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.sun.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

[error occurred during error reporting , id 0xc0000005]

再试一次：

    cl_device_partition_property core =  (CL_UNSIGNED_INT32)CL_DEVICE_PARTITION_BY_COUNTS;

错误：

CL_UNSIGNED_INT32 cannot be resolved to a type

这也不起作用：

   Pointer xyz=Pointer.to(core); // jocl's pointer type.
   clCreateSubDevices(device,xyz, 1, cpuCores, coreIDs);

编辑：问题解决了！谢谢。现在可以分区我的cpu：

Answer 1

我认为这是 JOCL 缺少的功能。 我认为您可以尝试这两种解决方法。

假设你要设置这个属性列表：

{ CL_DEVICE_PARTITION_BY_COUNTS, 3, 1, CL_DEVICE_PARTITION_BY_COUNTS_LIST_END, 0 }

（取自 http://software.intel.com/en-us/articles/opencl-device-fission-for-cpu-performance 的属性列表示例）。

解决方法 1：

cl_device_partition_property properties = new cl_device_partition_property();
properties.addProperty(CL.CL_DEVICE_PARTITION_BY_COUNTS, 3);
properties.addProperty(1, CL.CL_DEVICE_PARTITION_BY_COUNTS_LIST_END);

说明：addProperty 方法只是将 id 和 value 都附加到 long[] 数组的末尾，并将其转换为 Buffer：

public void addProperty(long id, long value)
{
    LongBuffer oldBuffer = (LongBuffer)getBuffer();
    long newArray[] = new long[oldBuffer.capacity()+2];
    oldBuffer.get(newArray, 0, oldBuffer.capacity());
    newArray[oldBuffer.capacity()-1] = id;
    newArray[oldBuffer.capacity()+0] = value;
    newArray[oldBuffer.capacity()+1] = 0;
    setBuffer(LongBuffer.wrap(newArray));
}

所以任何列表都可以像这样创建：

addProperty(item[0], item[1]);
addProperty(item[2], item[3]);
addProperty(item[4], item[5]);
addProperty(item[6], 0);

解决方法 2：

在org.jcol 包中创建一个类以访问受限方法setBuffer：

package org.jocl;

import java.nio.LongBuffer;

public class cl_device_partition_property_gateway {
    public static void set(cl_device_partition_property properties, long[] newArray) {
        properties.setBuffer(LongBuffer.wrap(newArray));
    }
}

那么就可以直接设置long[]数组了：

cl_device_partition_property properties = new cl_device_partition_property();
long[] values = { CL.CL_DEVICE_PARTITION_BY_COUNTS, 3, 1, 
    CL.CL_DEVICE_PARTITION_BY_COUNTS_LIST_END, 0 };
cl_device_partition_property_gateway.set(properties, values);