cudaMemGetInfo返回GTX 690的两个设备上的空闲存储器量的相同(cudaMemGet

我曾与GeForce GTX的690，而试图追查内存使用遇到的问题。一个简单的测试程序：

BOOST_AUTO_TEST_CASE(cudaMemoryTest) {

size_t mem_tot_0 = 0;
size_t mem_free_0 = 0;
size_t mem_tot_1 = 0;
size_t mem_free_1 = 0;

unsigned int mem_size = 100*1000000;

float* h_P = new float[mem_size];
for(size_t i = 0; i < mem_size; i++) {
    h_P[i] = 0.f;
}

cudaSetDevice(0);
cudaDeviceReset();
cudaMemGetInfo  (&mem_free_0, & mem_tot_0);
std::cout<<"Free memory before copy dev 0: "<<mem_free_0<<std::endl;

cudaSetDevice(1);
cudaDeviceReset();
cudaMemGetInfo  (&mem_free_1, &mem_tot_1);
std::cout<<"Free memory before copy dev 1: "<<mem_free_1<<std::endl;

cudaSetDevice(0);
float* P;
cudaMalloc((void**)&P, mem_size*sizeof(float));
cudaMemcpy((void*)P, h_P,  mem_size*sizeof(float), cudaMemcpyHostToDevice);

cudaSetDevice(0);
cudaMemGetInfo(&mem_free_0, & mem_tot_0);
std::cout<<"Free memory after copy  dev 0: "<<mem_free_0<<std::endl;

cudaSetDevice(1);
cudaMemGetInfo(&mem_free_1, &mem_tot_1);
std::cout<<"Free memory after copy dev 1: "<<mem_free_1<<std::endl;

BOOST_CHECK(mem_free_0 != mem_free_1);

cudaError_t err;
err = cudaGetLastError();
if(err!=cudaSuccess)
    std::cout<<"an error occurred"<<std::endl;

cudaSetDevice(0);
destroyMem(P);
delete [] h_P;
}

测试打印出：

1>  Free memory before copy dev 0: 1733173248
1>  Free memory before copy dev 1: 1688424448
1>  Free memory after copy  dev 0: 1289940992
1>  Free memory after copy dev 1: 1289940992     
CudaUtilsTest.cpp(47): error in "cudaMemoryTest": check mem_free_0 != mem_free_1 failed

的问题是，在分配之后的空闲内存在设备1上的量是完全一样的设备上0，这不应该是这样的，因此该问题必须处于cudaMemGetInfo和/或cudaSetDevice。任何人在同样的问题上运行，还是有别的东西根本错误的测试有人能指出？

在Windows 7上，Visual Studio 2010中，CUDA软件开发包5.0上运行的代码，代码生成编译：compute_30，sm_30

编辑2013年4月22日

我这个问题继续进行试验，似乎cudaSetDevice工作正常，这可以从cudaGetDevice调用的结果进行验证。我添加的设备0的复位内存分配测试后，似乎由cudaMemGetInfo返回可用内存大小是两个设备再次相同。我已经检查cuda_error_t的所有返回值在我自己的代码和所有的函数调用返回cudaSuccess。有没有人遇到与GTX 690以上descibed设置类似的问题？

最反感的测试代码：

BOOST_AUTO_TEST_CASE(cudaMemoryTest) {
size_t mem_tot_0 = 0;
size_t mem_free_0 = 0;
size_t mem_tot_1 = 0;
size_t mem_free_1 = 0;

int device_num = 0;

unsigned int mem_size = 100*1000000;

float* h_P = new float[mem_size];
for(size_t i = 0; i < mem_size; i++) {
    h_P[i] = 0.f;
}

cudaSetDevice(0);
cudaGetDevice(&device_num);
cudaDeviceReset();
cudaMemGetInfo  (&mem_free_0, & mem_tot_0);
std::cout<<"Free memory before copy dev 0: "<<mem_free_0<<" Device: "<<device_num<<std::endl;
cudaDeviceSynchronize();

cudaSetDevice(1);
cudaGetDevice(&device_num);
cudaDeviceReset();
cudaMemGetInfo  (&mem_free_1, & mem_tot_1);
std::cout<<"Free memory before copy dev 1: "<<mem_free_1<<" Device: "<<device_num<<std::endl;
cudaDeviceSynchronize();

cudaSetDevice(0);
cudaGetDevice(&device_num);
float* P;
cudaMalloc((void**)&P, mem_size*sizeof(float));
cudaMemcpy((void*)P, h_P,  mem_size*sizeof(float), cudaMemcpyHostToDevice);
cudaMemGetInfo(&mem_free_0, & mem_tot_0);
std::cout<<"Free memory after copy  dev 0: "<<mem_free_0<<" Device: "<<device_num<<std::endl;
cudaDeviceSynchronize();

cudaSetDevice(1);
cudaGetDevice(&device_num);
cudaMemGetInfo(&mem_free_1, &mem_tot_1);
std::cout<<"Free memory after copy dev 1: "<<mem_free_1<<" Device: "<<device_num<<std::endl;
cudaDeviceSynchronize();

BOOST_CHECK(mem_free_0 != mem_free_1);

cudaError_t err;
err = cudaGetLastError();
if(err!=cudaSuccess)
    std::cout<<"an error occurred"<<std::endl;

// Reset only device 0 and check both
cudaSetDevice(0);
cudaGetDevice(&device_num);
cudaDeviceReset();
cudaMemGetInfo  (&mem_free_0, & mem_tot_0);
std::cout<<"Free memory after second reset of device 0, dev 0: "<<mem_free_0<<" Device: "<<device_num<<std::endl;
cudaDeviceSynchronize();

cudaSetDevice(1);
cudaGetDevice(&device_num);
cudaMemGetInfo  (&mem_free_1, & mem_tot_1);
std::cout<<"Free memory after second device reset of device 0, dev 1: "<<mem_free_1<<" Device: "<<device_num<<std::endl;
cudaDeviceSynchronize();

delete [] h_P;
    }

测试输出：

1>  Free memory before copy dev 0: 1794379776 Device: 0
1>  Free memory before copy dev 1: 1751728128 Device: 1
1>  Free memory after copy  dev 0: 1351696384 Device: 0
1>  Free memory after copy dev 1: 1351696384 Device: 1
1>  CudaUtilsTest.cpp(353): error in "cudaMemoryTest": check mem_free_0 != mem_free_1 failed
1>  Free memory after second reset of device 0, dev 0: 1751728128 Device: 0
1>  Free memory after second device reset of device 0, dev 1: 1751728128 Device: 1

这是通过改变WDDM驱动程序设置来解决如下：