maximum allocation size not reached?

wimvd (2)
Hi,

To store data from a precalculation on about 1100 images and 830000 features, i'm trying to allocate about 3.5 gigs of memory but it seems not to be working. I was writing in C so I was using malloc, but I tried 'new' as well with the same problem. I'm running on a 64 bit linux server with 64 gigs of physical memory.

Elsewhere I've read that the maximum allocation size in bytes is theoretically determined by the size of size_t, which in my case is 8 bytes, using the formula 2^(8*sizeof(size_t)) - 1. This is 2^64-1 bytes, which should be more than enough. I've checked the actual numbers (of _total_size and total_size in the code below) being sent to malloc/new using gdb and their sizes are correct. Yet for some reason it will not allocate the complete amount of memory. It only seems to allocate about 2^31.005 bytes of memory, which is not enough. It also doesnt give any warnings or exceptions, not even when I try to write in the unallocated part later on. Only when I try to read out data from there I get a seg fault.

The code I'm using to allocate:

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int64 _total_size = (int64)step*mat->rows + sizeof(int) + CV_MALLOC_ALIGN;
        total_size = (size_t)_total_size;
        if(_total_size != (int64)total_size)
            CV_Error(CV_StsNoMem, "Too big buffer is allocated" );
        mat->refcount = (int*) new char[(size_t)total_size];


If anybody has an explanation for this I would be most grateful to hear it!

Thank you!

Wim
jsmith (5804)
What is your ulimit for memory usage?
wimvd (2)
[wvandam@cancer ~]$ ulimit -m
unlimited

Unlimited should work. :)
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