On Sun, Feb 24, 2013 at 3:40 PM, Gabor Greif <ggreif@gmail.com> wrote:
Hi all,

from what I gathered so far no emission of write barriers is needed when
 - running on a uniprocessor (-threaded or not)
 - running on a multiprocessor sans having linked with -threaded.

On Windows, the non-threaded RTS does I/O with forked threads; see rts/win32/IOManager.c and the async* functions in GHC.Conc.Windows.  I think this means that for Windows, we need those write barriers even for non-threaded.

-Joey