Rendering OSM data with Mapnik extremely slow


I set up a debian PC for rendering OSM data with mapnik.

Quad Core i7-2600K

The import of Austria into the PostgreSQL database was done in a few minutes. Rendering takes about 2 hours for zoom level 0 to 15.

Then I imported the complete planet. Took about 27 hours.
When I start rendering the tiles for the planet, the generation is extremely slow. It takes minutes just to render levels 0 to 3. That seems to be very strange because rendering Austria was done extremely fast. It takes about 10 sec to render one tile!!!
Why is there a difference on the rendering speed?
I didn’t change anything on the scripts or tools before rendering the planet, so everything is the same. The only obvious difference is the size of the database. The planet database ist about 250GB, where the database of Austria is much smaller.

I could also recognize that if rendering Austria all of the 8 CPUs are running in full speed (~95% load). During planet rendering the CPUs are nearly idle.

Any ideas?


Rendering for the lowest zoom levels is always slow. There is a lot of data to parse and render. That’s why even doesn’t dynamically rerender z0-z12 when the data changes. Only z13-z18 are dynamically rerendered there.

So, what’s your rendering speed on z13-z18 zoom levels?