osm2pgsql negative hit rate


i’m currently processing the latest osm_planet.pbf with osm2pgsql 0.83.0 and got a node_cache hit rate of -98.90%. What does this mean? I would have thought, that 0 % would be the worst case for a cache.

I’m running PostgreSQL 9.1 with PostGIS 2.0.3 on Ubuntu 12.04.

This is the command i’m using:

sudo osm2pgsql -c -s -d osm_planet --drop -C 11000 -v -U www-data --flat-nodes /usr/local/share/osm2pgsql/node.cache --exclude-invalid-polygon --unlogged --number-processes 4 planet-latest.osm.pbf

I know that 11000MB are not enough to hold all of the nodes, but i assumed that it would be beneficial to let Ubuntu do the swapping (i’ve got 12GB Swap Space). Am I wrong with that assumption?

Thanks in advance.