Curt Sampson <cjs@cynic.net> writes:

> > Not to mention that this would induce unnecessary overhead in threadless
> > programs.  Think m68k and VAX.
> 
> And much faster machines, too. A 500 MHz Pentium III can't do more
> than about 4-5 MB/sec to disk using getc() and putc() under Linux
> due to this sort of thing.

If you don't define _REENTRANT in our current code, you still get
normal, unlocked getc() and putc().  If you do, you get a function
rather than a macro.  That function will always call a locking
function, which may be a do-nothing one or a real, live one.

Under FreeBSD (and I planned on doing it for us, too) a global int
__is_threaded is non-zero if threading is in use.  I see no reason we
can't opt not to do these function calls if it is not set.  That means
that in the non-threaded (but thread "capable") the overhead to find
out a lock isn't needed is

	if (__is_threaded != 0)
		LOCK(...);

--Michael