DDR2 SDRAM max buffer lenght

So how do I get an overview of how the memory is used?

This is how I declare my buffer:

# define BUFFER_SIZE 750# define SSS_TX_BUF_SIZE 1500
...
volatile INT16U * buffer;       // buffer in the DDR2 SDRAM for DMA-Controller to write to
    
    /* Allocate memory for the circular sample buffer*/
    if((buffer = alt_uncached_malloc(BUFFER_SIZE * sizeof (INT16U))) == NULL)
    {
        printf("Can't allocate memory!");
    }  
...
send(conn.fd, (INT8U*)buffer, SSS_TX_BUF_SIZE, 0);  // send buffer content to PC
...

I could also declare it like: INT16U buffer[BUFFER_SIZE]; I think I was having trouble with presice buffering so I just tried the volatile and alt_uncashed_malloc()

Is that advisable?