Jon Burgess ha scritto: > On Tue, 2009-01-06 at 00:58 +0000, Roberto Navoni wrote: > >> Jon Burgess ha scritto: >> >>> On Mon, 2009-01-05 at 20:46 +0000, Roberto Navoni wrote: >>> >>> >>>> Hi, >>>> I have a question for OSM-Developer ;) >>>> So I'm trying mapnik for render italian OSM planet , but the performance >>>> on my sandbox is not so god . I'm using an old one hp laptop that use >>>> Ubuntu 8.04 as SO and as hardware use P4 3 Ghz 1 GByte of ram . I see >>>> that actualy are rendering only two tile for second. I'm usining >>>> postgress 8.3 as db. Are there some optimization for speed up the render >>>> time. >>>> How many mapnik i can start on a single cpu ? The performance is better ? >>>> >>>> >>> Are you using generate_tiles.py for rendering your tiles? >>> >>> >> Yes I use generate tiles >> >>> Is the web server under your control or are you serving static files via >>> a 3rd party web host? >>> >>> >>> >> I'm doing some test on my server ... I have complete control on it , I'm >> using Ubuntu 8.04 as Operating systems .. >> >>> The main tile.openstreetmap.org server uses mod_tile[1] which uses >>> several optimisation tricks to improve the performance but you can only >>> get the full benefit of this if you can install a custom Apache module. >>> >>> >>> >> Ok ... now I try It. >> >>> - multithreaded rendering (should exploit improve efficiency if you have >>> hyperthreading in your CPU). >>> - rendering and storing tiles in "meta-tiles" (8x8 at once). >>> - rendering on-demand, avoiding the need to pre-render lots of tiles >>> >>> If you can't install the Apache module then the mod_tile render daemon >>> can be used standalone with the speedtest & convert_meta tools to >>> generate a tree containing plain PNG files for uploading to a 3rd party >>> web host. I can provide more details if you are interested in this. >>> >>> Last time I benchmarked the tile.openstreetmap.org server it was >>> rendering approximately 600 tiles/s using 2 x dual core Opteron CPUs. >>> >>> >>> The osm.xml file has got significantly more complex since I did those >>> tests so the numbers are probably a bit slower now. Even so, your P4 >>> should manage more than 10 times your current performance. >>> >>> >>> >> Strange .. is possible that there're some problem on db configuration ? >> > > Possibly but postgres is not normally the bottleneck. > > >> >> With top I see the cpu usage by thread and i see that postgress using 15 >> % of cpu and mapnik use only 12% of cpu ... is possible that there're >> some setting to change on postgress or on mapnik ? >> > > Some CPU is taken by the "convert" step. Since this is a short lived > process it does generally appear in top. > > If you want to test, simply comment out the following lines in > generate_tiles.py and see how much faster it goes: > > command = "convert -colors 255 %s %s" % (tile_uri,tile_uri) > call(command, shell=True) > > For serving tiles you really want to use 256 colours since the tiles are > much smaller. If you are using a recent build of Mapnik then this > includes a faster colour conversion algorithm, just change the format > from png to png256 a line earlier: > > view.save(tile_uri,'png256') > > Jon > > Thank for your reply I see that convert use cpu with top for some times ... now I try do you know how i can update Mapnik 4.0 to the new one ? Best Regards Roberto > ------------------------------------------------------------------------ > > > Nessun virus nel messaggio in arrivo. > Controllato da AVG - http://www.avg.com > Versione: 8.0.176 / Database dei virus: 270.10.2/1876 - Data di rilascio: > 05/01/2009 9.44 > >
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