On Monday 15 January 2018, Paul Norman wrote: > > Latency does not matter with a pre-render task, so I've been > considering using extra-large metatiles. Has anyone tried this > before?
Not for normal rendering but for raster based data pre-processing/generalization tasks i am usually working with 16k metatiles. There are mostly two things that limit the usefulness of increasing tile size in this field - which might to some extent also apply to normal rendering: * memory footprint: Since the processing itself is usually single threaded you run several tiles in parallel and the memory demands for this must stay within the available memory. * processing time granularity: Since different parts of Earth take very different times to process it can happen that the slowest processing tiles are processed last leading to less than optimal parallelity in processing overall (i.e. you have one or two tiles dragging on in the end using only part of the ressources available while the rest is already finished). > Based on experience from metatiles 1-8 tiles across, as size > increases I expect query time and time to render to increase, but > time per tile to decrease. I don't know at what point this stops > being true. I would expect this to happen pretty fast, possibly 8x8 is already at or near the top. But it will likely depend quite a bit on the hardware used and the specific rendering task. -- Christoph Hormann http://www.imagico.de/ _______________________________________________ dev mailing list [email protected] https://lists.openstreetmap.org/listinfo/dev
