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Special Forums Hardware Filesystems, Disks and Memory mmap
# 1  
Old 07-30-2002
mmap
Hello. I'm writing some random access i/o software on Solaris 8 using mmap64 to memory map large files (my test file is ~25 GB).

The abbreviated code fragment is:

fd = open(cbuf,O_RDONLY|O_LARGEFILE);

struct stat statbuf;
fstat(fd,&statbuf);

off_t len = (off_t)statbuf.st_size; // len = 24974764635

map_ptr = (char *)mmap64(NULL,len,
PROT_READ,
MAP_NORESERVE|MAP_SHARED,
fd,0);

madvise(map_ptr,len,MADV_DONTNEED | MADV_RANDOM);

I think the problem may be mmap's 2nd argument which is (size_t) intead of (off_t) because I only have access up to 3.5 GB, which is about the value of the bottom 32 bytes of len.

Any help you can provide will be greatly appreciated.

Thanks,
gusm
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LEARN ABOUT DEBIAN

explain_mmap_or_die

explain_mmap_or_die(3)					     Library Functions Manual					    explain_mmap_or_die(3)

NAME

       explain_mmap_or_die - map file or device into memory and report errors

SYNOPSIS

       #include <libexplain/mmap.h>
       void *explain_mmap_or_die(void *data, size_t data_size, int prot, int flags, int fildes, off_t offset);
       void *explain_mmap_on_error(void *data, size_t data_size, int prot, int flags, int fildes, off_t offset);

DESCRIPTION

       The  explain_mmap_or_die  function  is  used to call the mmap(2) system call. On failure an explanation will be printed to stderr, obtained
       from the explain_mmap(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

       The explain_mmap_on_error function is used to call the mmap(2) system call. On failure an explanation will be printed to  stderr,  obtained
       from the explain_mmap(3) function, but still returns to the caller.

       data    The data, exactly as to be passed to the mmap(2) system call.

       data_size
	       The data_size, exactly as to be passed to the mmap(2) system call.

       prot    The prot, exactly as to be passed to the mmap(2) system call.

       flags   The flags, exactly as to be passed to the mmap(2) system call.

       fildes  The fildes, exactly as to be passed to the mmap(2) system call.

       offset  The offset, exactly as to be passed to the mmap(2) system call.

RETURN VALUE

       The explain_mmap_or_die function only returns on success, see mmap(2) for more information. On failure, prints an explanation and exits, it
       does not return.

       The explain_mmap_on_error function always returns the value return by the wrapped mmap(2) system call.

EXAMPLE

       The explain_mmap_or_die function is intended to be used in a fashion similar to the following example:
	      explain_mmap_or_die(data, data_size, prot, flags, fildes, offset);

SEE ALSO

       mmap(2) map file or device into memory

       explain_mmap(3)
	       explain mmap(2) errors

       exit(2) terminate the calling process

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2010 Peter Miller

															    explain_mmap_or_die(3)