[英]What is the meaning of CUFFT_ALLOC_FAILED return value when calling cufftGetSize*()?
cufftGetSize*() is not supposed to allocate any memory, and it doesn't (I checked available memory before and after calling cufftGetSize*). cufftGetSize *()不应该分配任何内存,它也不分配(我在调用cufftGetSize *之前和之后检查了可用内存)。 Does it return CUFFT_ALLOC_FAILED if a later allocation would fail?
如果以后的分配失败,是否返回CUFFT_ALLOC_FAILED?
Example code: 示例代码:
#include <iostream>
#include <stdio.h>
#include <cuda.h>
#include <cufft.h>
int main() {
for (int N=1; N<1800; ++N) {
std::cerr << "N = "<< N << " ";
cufftResult r;
cufftHandle planR2C;
cudaDeviceReset();
r = cufftCreate(&planR2C);
if(r) return 1;
r = cufftSetCompatibilityMode(planR2C, CUFFT_COMPATIBILITY_FFTW_PADDING);
if(r) return 1;
r = cufftSetAutoAllocation(planR2C, 0);
if(r) return 1;
size_t workSize;
r = cufftGetSize3d(planR2C, 1800, 1800, N, CUFFT_R2C, &workSize);
if(r==CUFFT_ALLOC_FAILED) std::cerr << "CUFFT_ALLOC_FAILED\n";
std::cerr << " Estimated workSize: "
<< workSize / ( 1024 * 1024 )
<< " MB" << std::endl;
cudaDeviceReset();
}
std::cerr << "****** Done.\n";
return 0;
}
On a GPU with 4693 MB free memory at the start of the process, above code produces the following output: 在此过程开始时,在具有4693 MB可用内存的GPU上,以上代码产生以下输出:
N = 1 Estimated workSize: 197 MB
N = 2 Estimated workSize: 395 MB
...
N = 15 Estimated workSize: 791 MB
N = 16 Estimated workSize: 197 MB
N = 17 CUFFT_ALLOC_FAILED
N = 18 Estimated workSize: 222 MB
...
From N=73 on all odd N fail and even N pass. 从N = 73开始,所有奇数N个失败,甚至N个通过。 From N=166 all N fail.
从N = 166开始,所有N均失败。
Since required memory would not grow linearly with N, I assume (!) that the answer to my question indeed is: "it return[s] CUFFT_ALLOC_FAILED if a later allocation would fail" Although, a prove of that statement would be nice. 由于所需的内存不会随N线性增长,因此我假设(!)我的问题的答案确实是:“如果以后的分配失败,它将返回CUFFT_ALLOC_FAILED”尽管,对该语句的证明将是不错的。
(My problem arises under CUDA 5.5.22, I have not checked any other version) (我的问题出现在CUDA 5.5.22下,我没有检查任何其他版本)
To mark this question answered: 要标记此问题的答案:
Confidence among readers is high that "CUFFT_ALLOC_FAILED return value when calling cufftGetSize*()" actually means "CUFFT_ALLOC_WOULD_FAIL". 读者对“调用cufftGetSize *()时的CUFFT_ALLOC_FAILED返回值”实际上意味着“ CUFFT_ALLOC_WOULD_FAIL”的信心很高。
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