[ofa-general] Drop in TCP performance when using OFED?

[Jan Ruffing]

Hallo,

After I installed the OFED (1.4 beta), I noticed a drop in TCP
performance via Infiniband: from 10 GBit/s to less than 8 GBit/s.
Is that "expected behaviour"? Is there a way to avoid this performance loss?

The HCA used in both test machines is a Mellanox Infinihost III Lx DDR
HCA. Both machines run OpenSuse 11 with a 2.6.25.16 Kernel.


Performance with Open Suse 11 "out of the box", using Open Suse 11
Infiniband packages:

tamara iperf-2.0.4/src> ./iperf -c 192.168.2.2 -l 3M
------------------------------------------------------------
Client connecting to 192.168.2.2, TCP port 5001
TCP window size: 515 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.2.1 port 47730 connected with 192.168.2.2 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 11.6 GBytes 10.0 Gbits/sec


Performance after the Installation of ODED 1.4. beta:

tamara iperf-2.0.4/src> ./iperf -c 192.168.2.2 -l 3M
------------------------------------------------------------
Client connecting to 192.168.2.2, TCP port 5001
TCP window size:   902 KByte (default)
------------------------------------------------------------
[  3] local 192.168.2.1 port 38864 connected with 192.168.2.2 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  8.43 GBytes  7.24 Gbits/sec


Thanks in advance,
Jan

-- 
Jan Ruffing
Software Developer

Motama GmbH
Lortzingstraße 10 · 66111 Saarbrücken · Germany
tel +49 681 940 85 50 · fax +49 681 940 85 49
ruffing at motama.com · www.motama.com

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