Thanks for the quick reply Patrick. > Presumably I could do the same for world preparation & routing? Have, perhaps > a 100GB+ swap file, ideally on an SSD.
>This will fall apart when you have some actual load pressure on the >system. We need random access to memory, which will create a lot of >page faults (== slow). Even an SSD is not even close to memory speed. >You have two options: > split the datasets > get a bigger server I would imagine that is the case for the standard http server. I was thinking of using it as a linked library from a C++ program. Splitting the datasets by continent is a possibility though. (writing a C# interface was another thought, but that would be a different use case and definitely with smaller datasets) Cheers, Richard On Thu, Sep 17, 2015 at 4:37 PM, Patrick Niklaus <patrick.nikl...@student.kit.edu> wrote: > W.r.t. the pre-preprocessing you are correct. > >> What is that extra power used for? > > Including all sorts of external data sources. Also the logic in the > lua profiles is not just replaceable by simple key-value pairs, OSM > requires you to handle a lot of special cases. > >> Presumably I could do the same for world preparation & routing? Have, >> perhaps a 100GB+ swap file, ideally on an SSD. > > This will fall apart when you have some actual load pressure on the > system. We need random access to memory, which will create a lot of > page faults (== slow). Even an SSD is not even close to memory speed. > > You have two options: > - split the datasets > - get a bigger server > > Cheers, > Patrick > > > On Thu, Sep 17, 2015 at 10:06 PM, Richard Marsden <winw...@gmail.com> wrote: >> I've been evaluating OSRM, using it primarily as a library from C++. >> >> I believe I've determined the answer to most of the questions, but I'm >> also looking for confirmation. >> (I understand the reason for these constraints - the trade-off of >> speed vs flexibility) >> >> First, road speeds are set with 'profile.lua' at the osrm-extract >> stage. This filters out unnecessary roads (eg. foot paths for car >> routing), but also applies the road speeds. >> If I wish to change the speed profile, I need to regenerate the road >> network with osrm-extract and osrm-routed. >> Correct? >> >> If I wanted different speeds for the final distance/time calculations, >> I could use the returned route, and apply my own speed table according >> to the road type of each road segment. This would not, of course, >> change the route geometry is calculated. >> >> If I want a shortest route (distance optimized) instead of a quickest >> route (time optimized), I need to set all the road speeds to the same >> speed and regenerate the network. I.e. osrm does not directly support >> the concept of a "shortest route". >> >> The profile is provided with a LUA file. I had to look this one up :-) >> Looks a useful scripting language, but why is this profile a script >> file, and not a simple configuration file of constants (eg. key-value >> pairs)? >> Seems like an unnecessary complexity - I'd like to understand the >> perceived advantages. What is that extra power used for? >> >> Finally, the memory usage... I saw a reference to the server requiring >> 40GB of memory for pan-European routing. Presumably that could be >> offset with a large swap file(?) >> A large swap file has worked well when I was testing the US-South >> region on an 8GB machine. >> Presumably I could do the same for world preparation & routing? Have, >> perhaps a 100GB+ swap file, ideally on an SSD. >> >> >> Cheers, >> >> Richard Marsden >> >> _______________________________________________ >> OSRM-talk mailing list >> OSRM-talk@openstreetmap.org >> https://lists.openstreetmap.org/listinfo/osrm-talk > > _______________________________________________ > OSRM-talk mailing list > OSRM-talk@openstreetmap.org > https://lists.openstreetmap.org/listinfo/osrm-talk _______________________________________________ OSRM-talk mailing list OSRM-talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/osrm-talk
