Question

CUDA设备上的类型大小理论上与主机平台上的大小不同。那么，在我的CUDA设备上表达＆＃34; sizeof（T）的惯用方式＆＃34;，在代码中 - 除了将你自己的id类型地图滚动到你知道的值之外？＆lt; < / p>

Answer 1

任何当前支持的CUDA平台都不需要您提出任何问题。 CUDA工具链与主机编译器和主机C ++运行时库高度集成的原因之一是，保证主机和设备上基本类型的大小始终匹配。不需要惯用的大小翻译。 sizeof的结果对于主机和设备始终是相同的。请注意，基本类型的大小可能因平台而异（Windows是LLP64 / IL32P64平台，Linux和OS X是LP64 / I32LP64平台），但这对GPU没有影响。

另请注意，GPU可以对复合类型强加对齐要求，这可能意味着编译后的大小与您的预期不同。适用的条件在文档中有详细讨论。

例如，请考虑以下简单的示例代码：

#include <cstdio>

__device__ __host__ __noinline__ void printsizes(const char* title)
{
    printf("%s\n", title);
    printf("sizeof(void*) = %ld\n", (unsigned long)sizeof(void*));
    printf("sizeof(char) = %ld\n", (unsigned long)sizeof(char));
    printf("sizeof(bool) = %ld\n", (unsigned long)sizeof(bool));
    printf("sizeof(short) = %ld\n", (unsigned long)sizeof(short));
    printf("sizeof(int) = %ld\n", (unsigned long)sizeof(int));
    printf("sizeof(long) = %ld\n", (unsigned long)sizeof(long));
    printf("sizeof(long long) = %ld\n", (unsigned long)sizeof(long long));
}

__global__ void printkernel()
{
    printsizes("On the device:");
}

int main()
{
    printsizes("On the host:");

    printkernel<<<1,1>>>();
    cudaDeviceSynchronize();
    cudaDeviceReset();

    return 0;
}

在Linux 64平台上编译并运行产生：

$ nvcc -arch=sm_52 -m64 -o sizeof64 sizeof.cu
$ ./sizeof64
On the host:
sizeof(void*) = 8
sizeof(char) = 1
sizeof(bool) = 1
sizeof(short) = 2
sizeof(int) = 4
sizeof(long) = 8
sizeof(long long) = 8
On the device:
sizeof(void*) = 8
sizeof(char) = 1
sizeof(bool) = 1
sizeof(short) = 2
sizeof(int) = 4
sizeof(long) = 8
sizeof(long long) = 8

基于64位Windows平台构建它：

>nvcc -arch=sm_21 -m64 sizes.cu
sizes.cu
   Creating library a.lib and object a.exp
>a.exe
On the host:
sizeof(void*) = 8
sizeof(char) = 1
sizeof(bool) = 1
sizeof(short) = 2
sizeof(int) = 4
sizeof(long) = 4
sizeof(long long) = 8
On the device:
sizeof(void*) = 8
sizeof(char) = 1
sizeof(bool) = 1
sizeof(short) = 2
sizeof(int) = 4
sizeof(long) = 4
sizeof(long long) = 8

基于32位Windows平台构建它：

>nvcc -arch=sm_21 -m32 sizes.cu
sizes.cu
   Creating library a.lib and object a.exp

C:\Users\david\Documents>a.exe
On the host:
sizeof(void*) = 4
sizeof(char) = 1
sizeof(bool) = 1
sizeof(short) = 2
sizeof(int) = 4
sizeof(long) = 4
sizeof(long long) = 8
On the device:
sizeof(void*) = 4
sizeof(char) = 1
sizeof(bool) = 1
sizeof(short) = 2
sizeof(int) = 4
sizeof(long) = 4
sizeof(long long) = 8

请注意，void *和long的大小可能因平台而异。但在每种情况下，GPU大小都与主机大小相匹配。这是CUDA驱动程序和GPU运行时的基本设计原则。

在我的CUDA设备上，＆＃34; sizeof类型T的成语是什么＆＃34;？

1 个答案: