Gluster users - Apr 2009 - slow concurrent access in same client

We have production servers that have 8GB memory on each client and server.
But we found that running multiple processes in same client machine will
degrade the total IO throughput.
here is the testing case:
Reading 10,000 random files using only one process: 45seconds
Open 2 processes, each to read 10,000 random files: Process 1 took 98
seconds, process 2 took 102 seconds.

using 'top' to check the system resource, on server side, the system is
97%
idle, on client side it is 85% idle.
Any idea why gluster client can not handle multiple processes to improve
aggregated IO throughput? I am using ver 2.00rc1.

any optimization idea is appreciated.

thanks
Watishi


-- client configuration file
volume remote_1
  type protocol/client
  option transport-type tcp/client
   option remote-host server1
  option remote-subvolume volume_1-brick
end-volume

volume remote_2
  type protocol/client
  option transport-type tcp/client
   option remote-host server2
  option remote-subvolume volume_2-brick
end-volume

volume remote_3
  type protocol/client
  option transport-type tcp/client
   option remote-host server3
  option remote-subvolume volume_3-brick
end-volume

volume remote_4
  type protocol/client
  option transport-type tcp/client
   option remote-host server4
  option remote-subvolume volume_4-brick
end-volume

volume bricks
  type cluster/distribute
  subvolumes remote_1 remote_2 remote_3 remote_4

end-volume


--server gluster configure file

volume volume_2-posix
 type storage/posix
 option directory /data/export/volume_2
end-volume

volume volume_2-locks
  type features/locks
  subvolumes volume_2-posix
end-volume

volume volume_2-brick
 type performance/io-threads
 option thread-count 9
 subvolumes volume_2-locks
end-volume

volume server
 type protocol/server
 option transport-type tcp
 option auth.addr.volume_2-brick.allow *
subvolumes volume_2-brick
end-volume
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