Is the swap feature useful?

[Jason Evans]

Over the two years that jemalloc has had the swap feature (optionally 
compiled in if --enable-swap is specified to configure), I've received 
many general questions about the feature, but I have yet to hear of a 
single person actually using it in an application.  As such I'm 
considering removing the feature in jemalloc 3.0.0.  Does anyone find 
the feature sufficiently useful to warrant its continued existence?

Thanks,
Jason