[PVFS2-developers] Benchmark results.

[Julian Martin Kunkel]

Hi,
I attached some benchmark results for mpi-create on chiba. Every node does 
create 1000 files. The clients and servers are disjoint. In the x-direction 
the number of clients and severs increase. Every server is a meta and data 
server. I think it looks like the creation rate is constant for  
server/nodecount. I think this is indication that scalability is good up to 
35 clients and server nodes. Metadata syncing is disabled for dbpf. The pvfs2 
sourcecode base is 3 weeks old.
It was not that easy as I thought to get things running on chiba, so it take  
more time to run benchmarks. 

The current DBPF implementation could be better,
for example with 50 clients (2 per node), 25 servers and 5000 files per node 
DBPF slows down to 25 creates/sec (5039 seconds runtime) while TAS creates 
770 (114 seconds) and ALT creates 440 (281 seconds).

ALT refers to a new (simple) implementation I did, this implementation does 
not cache anything and is working with berkeley db. Caching of Metadata is  
done by berkeley db. For stream IO I use separate threads and a queue in a 
similar way you do. I just use one db for attributes and one for key/value 
pairs, so it is not necessary to open / close databases and the berkeley db 
cache is better used. For large directories keyval iteration is slower with 
my implementation because it is not that easy to find the last position in 
the database as with dbpf because the db layout is completly different. But 
with a change in the interface this could be compensated.

On monday you can find a website with a lot more benchmark results of our 5 
node cluster here:
http://www.rzuser.uni-heidelberg.de/~jkunkel2/

With more than 2GByte testdata using mpi-io-test the server still hung up 
after a while. I upgraded my cvs version today but it still remains. I think 
it must be a timing issue, with 1 client everything is working fine. I'll try 
to reproduce the error on chiba.

Have a nice day
Julian
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