Josh Berkus: Wrong defaults for zone_reclaim_mode on Linux

My coworker Jeff Frost just published a writeup on "zone reclaim mode" in Linux, and how it can be a problem.  Since his post is rather detailed, I wanted to give a "do this" summary:

1. zone_reclaim_mode defaults to the wrong value for database servers, 1, on some Linux distributions, including Red Hat.
2. This default will both cause Linux to fail to use all available RAM for caching, and throttle writes.
3. If you're running PostgreSQL, make sure that zone_reclaim_mode is set to 0.

Frankly, given the documentation on how zone_reclaim_mode works, I'm baffled as to what kind of applications it would actually benefit.  Could this be another Linux misstep, like the OOM killer?