> I don't know POSIX / UNIX all that well.  Does it require that a stat
> call updates atime?  Because that's one of those "how does it ever
> work" head-scratchers.  (Maybe everybody always disables atime these
> days?  I don't think I do.)

I think most Linux distributions disable it for you; or, rather, they
use the "relatime" mount option which is a smart cheat:

relatime
    Update  inode  access  times  relative  to  modify  or change time.
    Access time is only updated if the previous access time was earlier
    than  the  current  modify or change time. (Similar to noatime, but
    doesn't break mutt or other applications that need  to  know  if  a
    file has been read since the last time it was modified.)