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I would like to suggest to add st_atim, st_mtim and st_ctim attributes in os.stat_result objects returned by os.stat(). These attributes would be 2-tuples containing number of seconds and number of nanoseconds. They would expose relevant functionality from libc's stat() and provide better precision than floating-point-based st_atime, st_mtime and st_ctime attributes.
st_atim, st_mtim and st_ctim attributes would be available only if Python has been built on system with libc supporting st_atim, st_mtim and st_ctim in stat structure.
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html 

I think this is a duplicate of #11457.

Actually issue #11941 should be a dependency of issue #11457. Issue #11941 is only about os.stat(), while issue #11457 proposes changes also in other places (e.g. tarfile module).

Ok, that's true, reopening.

Attached is a patch for review.
It adds st_atim, st_ctim and st_mtim.
They are defined even when the underlying system does not have nanosecond precision.

st_atim, st_mtim and st_ctim were introduced in 2008 version of POSIX (and were earlier provided by glibc as an extension). To avoid compilation failure with some exotic versions of libc, I suggest:
- In configure.in:
AC_CHECK_MEMBERS([struct stat.st_atim])
AC_CHECK_MEMBERS([struct stat.st_ctim])
AC_CHECK_MEMBERS([struct stat.st_mtim])
- In Modules/posixmodule.c:
 PyObject *atim = Py_BuildValue(_STAT_FMT,
 st->st_atime,
#ifdef HAVE_STRUCT_STAT_ST_ATIM
 st->st_atim.tv_nsec
#else
 0
#endif
 );
...

Here is an updated patch that uses the atim, ctim and mtim variables (which are assigned based on various #ifdefs).
This should now work on Linux, BSD and Windows.

I'm not sure if that's deliberate, but the new attributes don't appear in the result repr():
>>> s = os.stat("LICENSE")
>>> s
posix.stat_result(st_mode=33204, st_ino=524885, st_dev=2053, st_nlink=1, st_uid=500, st_gid=500, st_size=14597, st_atime=1307474138, st_mtime=1299630588, st_ctime=1299630588)
>>> s.st_mtim
(1299630588, 90781883)
In the docs, you also need a "versionchanged" tag to mention that the attributes were added in 3.3.
The patch fails to compile under Windows: MSVC forbids variable declarations after code (atim, ctim, mtim), you have to put them at the beginning of a block. Once this is fixed, it seems to work ok.

Given Guido's rejection of PEP 410, this won't happen, so I'm closing this bug. Our BFDL has specifically rejected any of the complicated representations; he ruled that all we need are new _ns fields representing the time in nanoseconds, and to accept a "ns=" argument for os.utime and its ilk. Please see bug #14127 for discussion of that change.