How to allocate all available global memory on the GeForce GTX 690 device?

Question

Now I need to allocate all available memory with cuda technology. I do it with Tesla C2050, Quadro 600 and GeForce GTX 560 Ti by: First, I allocate 0 bytes of global memory on d

Answer 1

I recently remembered, about the "Page-Locked" mechanism in cuda. I test it, and do not get satisfactory results of performance (calculation using this mechanism is ten times slower, then a version with very limited memory reservation feature for Windows with GeForce GTX 690). I just thought that copying the data to device for later calculation and writing back will be done automatically, but in fact the memory of the device is not involved.

Answer 2

I could rerun your examples and came to the same result.

I tried to tackle the problem from the other side, and tried to allocate blocks of decreasing size.

int (*reservedMemory);
size_t const NBlockSize = 1300 *1024*1024; 
size_t freeMemory, totalMemory;
cudaError_t nErr = cudaSuccess;
size_t nTotalAlloc=0;
while( nErr == cudaSuccess )
{
    cudaMemGetInfo(&freeMemory, &totalMemory);
    std::cout << "===========================================================" << std::endl;
    std::cout << "Free/Total(kB): " << freeMemory/1024 << "/" << totalMemory/1024 << std::endl;

    size_t nAllocSize = NBlockSize;
    while( nAllocSize > freeMemory )
        nAllocSize /= 2;

    nErr = cudaMalloc(&reservedMemory, nAllocSize );
    if( nErr == cudaSuccess )
        nTotalAlloc += nAllocSize;
    std::cout << "AllocSize(kB): " << nAllocSize/1024 << ", error: " << cudaGetErrorString(nErr) << std::endl;

}
std::cout << "TotalAlloc/Total (kB): " << nTotalAlloc/1024 << "/" << totalMemory/1024 << std::endl;

The program starts with a block of size NBlockSize and if freeMemory decreases, also decrease nAllocSize. Looking at the output below, it seems cudaMalloc behaves a bit unpredictable when allocating blocks which are kind of big related to freeMemory. At one point it manages to allocate more than 98% of free memory, at another point it fails to allocate 800MB out of 1GB of available memory.

The most interesting run is the one with starting block size of 700MB. It manages to 1400kB out of 1428 in the last successful loop, and fails at allocating 10 out of 20 kB in the next run.

Depending on the starting size, the program managed to allocate all free space except 8kB at the best run, and left over one gigabyte on the worst.

D:\Buildx64\Test\GMDT\Debug>Gdmt.exe
NBlockSize(MB): 1000
===========================================================
Free/Total(kB): 1797120/2097152
AllocSize(kB): 1024000, percentage of freememory: 0.569801, error: no error
===========================================================
Free/Total(kB): 773120/2097152
AllocSize(kB): 512000, percentage of freememory: 0.662252, error: no error
===========================================================
Free/Total(kB): 261120/2097152
AllocSize(kB): 256000, percentage of freememory: 0.980392, error: no error
===========================================================
Free/Total(kB): 5128/2097152
AllocSize(kB): 4000, percentage of freememory: 0.780031, error: no error
===========================================================
Free/Total(kB): 1032/2097152
AllocSize(kB): 1000, percentage of freememory: 0.968992, error: no error
===========================================================
Free/Total(kB): 8/2097152
AllocSize(kB): 7, percentage of freememory: 0.976563, error: out of memory
TotalAlloc/Total (kB): 1797000/2097152


D:\Buildx64\Test\GMDT\Debug>Gdmt.exe
NBlockSize(MB): 1200
===========================================================
Free/Total(kB): 1796864/2097152
AllocSize(kB): 1228800, percentage of freememory: 0.683858, error: no error
===========================================================
Free/Total(kB): 568072/2097152
AllocSize(kB): 307200, percentage of freememory: 0.540777, error: no error
===========================================================
Free/Total(kB): 260872/2097152
AllocSize(kB): 153600, percentage of freememory: 0.588795, error: no error
===========================================================
Free/Total(kB): 107272/2097152
AllocSize(kB): 76800, percentage of freememory: 0.715937, error: no error
===========================================================
Free/Total(kB): 30472/2097152
AllocSize(kB): 19200, percentage of freememory: 0.630087, error: no error
===========================================================
Free/Total(kB): 11272/2097152
AllocSize(kB): 9600, percentage of freememory: 0.851668, error: no error
===========================================================
Free/Total(kB): 1672/2097152
AllocSize(kB): 1200, percentage of freememory: 0.717703, error: no error
===========================================================
Free/Total(kB): 392/2097152
AllocSize(kB): 300, percentage of freememory: 0.765306, error: out of memory
TotalAlloc/Total (kB): 1796400/2097152

D:\Buildx64\Test\GMDT\Debug>Gdmt.exe
NBlockSize(MB): 800
===========================================================
Free/Total(kB): 1844448/2097152
AllocSize(kB): 819200, percentage of freememory: 0.444144, error: no error
===========================================================
Free/Total(kB): 1025248/2097152
AllocSize(kB): 819200, percentage of freememory: 0.799026, error: out of memory
TotalAlloc/Total (kB): 819200/2097152

D:\Buildx64\Test\GMDT\Debug>Gdmt.exe
NBlockSize(MB): 700
===========================================================
Free/Total(kB): 1835528/2097152
AllocSize(kB): 716800, percentage of freememory: 0.390514, error: no error
===========================================================
Free/Total(kB): 1118740/2097152
AllocSize(kB): 716800, percentage of freememory: 0.640721, error: no error
===========================================================
Free/Total(kB): 401940/2097152
AllocSize(kB): 358400, percentage of freememory: 0.891675, error: no error
===========================================================
Free/Total(kB): 43540/2097152
AllocSize(kB): 22400, percentage of freememory: 0.514469, error: no error
===========================================================
Free/Total(kB): 21140/2097152
AllocSize(kB): 11200, percentage of freememory: 0.529801, error: no error
===========================================================
Free/Total(kB): 9876/2097152
AllocSize(kB): 5600, percentage of freememory: 0.567031, error: no error
===========================================================
Free/Total(kB): 4244/2097152
AllocSize(kB): 2800, percentage of freememory: 0.659755, error: no error
===========================================================
Free/Total(kB): 1428/2097152
AllocSize(kB): 1400, percentage of freememory: 0.980392, error: no error
===========================================================
Free/Total(kB): 20/2097152
AllocSize(kB): 10, percentage of freememory: 0.546875, error: out of memory
TotalAlloc/Total (kB): 1835400/2097152