is externaltask_affinity still supported?

System

We have a situation that one of my colleagues thinks might be addressed well by setting the externaltask_affinity config directive in iw.cfg. When I went to look it up in the documentation, I couldn't find anything about it. After some additional searching, it looks like it was documented on page 36 of the 6.5.0 admin guide, but it is not in the 6.7.1SP1 admin guide at all. That raises an interesting question - is this still a supported feature or not?

If it is supported, does it actually work?