On Mon, 30 Jun 2008 15:40:30 +0530 Krishna Kumar2 <krkumar2@xxxxxxxxxx> wrote: > Dean Hildebrand <seattleplus@xxxxxxxxx> wrote on 06/27/2008 11:36:28 PM: > > > One option might be to try using O_DIRECT if you are worried about > > memory (although I would read/write in at least 1 MB at a time). I > > would expect this to help at least a bit especially on reads. > > > > Also, check all the standard nfs tuning stuff, #nfsds, #rpc slots. > > Since with a loopback you effectively have no latency, you would want to > > ensure that neither the #nfsds or #rpc slots is a bottleneck (if either > > one is too low, you will have a problem). One way to reduce the # of > > requests and therefore require fewer nfsds/rpc_slots is to 'cat > > /proc/mounts' to see your wsize/rsize. Ensure your wsize/rsize is a > > decent size (~ 1MB). > > Number of nfsd: 64, and > sunrpc.transports = sunrpc.udp_slot_table_entries = 128 > sunrpc.tcp_slot_table_entries = 128 > > I am using: > > mount -o > rw,bg,hard,nointr,proto=tcp,vers=3,rsize=65536,wsize=65536,timeo=600,noatime > localhost:/local /nfs > > I have also tried with 1MB for both rsize/wsize and it didn't change the BW > (other than > mini variations). > > thanks, > > - KK > Recently I spent some time with others here at Red Hat looking at problems with nfs server performance. One thing we found was that there are some problems with multiple nfsd's. It seems like the I/O scheduling or something is fooled by the fact that sequential write calls are often handled by different nfsd's. This can negatively impact performance (I don't think we've tracked this down completely yet, however). Since you're just doing some single-threaded testing on the client side, it might be interesting to try running a single nfsd and testing performance with that. It might provide an interesting data point. Some other thoughts of things to try: 1) run the tests against an exported tmpfs filesystem to eliminate underlying disk performance as a factor. 2) test nfsv4 -- nfsd opens and closes the file for each read/write. nfsv4 is statelful, however, so I don't believe it does that there. As others have pointed out though, testing with client and server on the same machine is not necessarily eliminating performance bottlenecks. You may want to test with dedicated clients and servers (maybe on a nice fast network or with a gigE crossover cable or something). -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
