On Mon Jun 09, 2008 at 12:0506PM +0200, spaetz wrote: > On Mon, Jun 09, 2008 at 10:31:19AM +0200, Jiri Klement wrote: > > Btw. Is tilesets unzipping done on hdd or ramdisc? Using ramdisc > > should improve performance a bit without extra effort. > > It's unzipped to the disk partition where the tiles are. So the final > mv to their end destination is cheap. Unzipping into RAM disk and > then moving them to the partition were equally expensive. We had > tried a RAM disk before on the dev server.
I had a look at the code recently, and I was quite surprised that the unzipping is already done on the NFS storage and not locally. I'm not sure if there wouldn't be a speedup when unzipping and doing the verification of the tileset locally - as you (at least) save a few NFS round trips when going through all files in the directory - and as far as I remember, this is done a few times. When doing this stuff on local disks, there wouldn't be much difference when doing the extraction into a ram disk and operation on the files there compared to extracting the files to the correct volume and doing the necessary there. Directory Entries are held in the I/O cache of the system and therefore, it's regardless whether the files are in a ram disk or on a real disk. However, I would expect the system to send out NFS requests to the server, when the same operation happens on a NFS mount (because the nfs client *can't* know the directory didn't change!) and therefore, this operation should be slower than local or ram disks. I wasn't able to do a verification of this theory so far, and it wouldn't be a big speedup, but we're currently on the limit, so everything can help. -- Michael Bergbauer <[EMAIL PROTECTED]> Munich, Germany _______________________________________________ Tilesathome mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/tilesathome
