Maximum using global memory

Accelerated Computing CUDA CUDA Programming and Performance
1

Hi.
Does any body pay attention at the maximum size data can be used in Global memory.
My GPU is geforce 8800GT, OS: XP32 sv2, MS C++ 2005.
My Global memory is 512 MB, But the maximum data I can store in Global memory is 202MB.
so 512 - 202 = 300MB can not use. does any body knows why???
I checked CUDA Profile, and *.cutil to confirm that i didn’t use Local memory.
So I think that 300MB is reserve for CUDA array. Is it right???
Thank. :)

2

How many CUDA contexts or host threads do you create?

CUDA contexts allocate a lot of memory.

test code.

[codebox]#include <stdio.h>

#include <cuda.h>

int main(int argc, char* argv)

{

cuInit( 0 );

CUdevice dev;

cuDeviceGet( &dev, 0 );

CUcontext context[5];

for (int i = 0;  i < 5;  ++i) {

    cuCtxCreate( &context[i], CU_CTX_SCHED_AUTO, dev );

    unsigned int free=0, total=0;

    cuMemGetInfo( &free, &total);

    printf( "free=%u total=%u\n", free, total );

}

printf( "\n" );

for (int i = 4; i >=0;  --i) {

    cuCtxDestroy( context[i] );

    unsigned int free=0, total=0;

    cuMemGetInfo( &free, &total);

    printf( "free=%u total=%u\n", free, total );

}

return 0;

}

[/codebox]