lhecking@xxxxxxxxxxxxxxxxxxxxx wrote:
> I have a Dell server with four bonded, gigabit interfaces. Bonding mode is
> 802.3ad, xmit_hash_policy=layer3+4. When testing this setup with iperf,
> I never get more than a total of about 3Gbps throughput. Is there anything
> to tweak to get better throughput? Or am I running into other limits (e.g.
> was reading about tcp retransmit limits for mode 0).
>
> The iperf test was run with iperf -s on the server, and iperf -c server
> on four clients connected to the same switch.
>
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size: 85.3 KByte (default)
> ------------------------------------------------------------
> [ 4] local 10.10.15.193 port 5001 connected with 10.10.15.184 port 48588
> [ 5] local 10.10.15.193 port 5001 connected with 10.10.15.187 port 49231
> [ 6] local 10.10.15.193 port 5001 connected with 10.10.15.188 port 53197
> [ 7] local 10.10.15.193 port 5001 connected with 10.10.15.189 port 55309
> [ ID] Interval Transfer Bandwidth
> [ 4] 0.0-10.0 sec 1.10 GBytes 941 Mbits/sec
> [ 5] 0.0-10.0 sec 872 MBytes 728 Mbits/sec
> [ 6] 0.0-10.0 sec 318 MBytes 267 Mbits/sec
> [ 7] 0.0-10.0 sec 1.10 GBytes 939 Mbits/sec
> [ 8] local 10.10.15.193 port 5001 connected with 10.10.15.184 port 48589
> [ 4] local 10.10.15.193 port 5001 connected with 10.10.15.187 port 49234
> [ 5] local 10.10.15.193 port 5001 connected with 10.10.15.188 port 38864
> [ 6] local 10.10.15.193 port 5001 connected with 10.10.15.189 port 55311
> [ 8] 0.0-10.0 sec 1.10 GBytes 941 Mbits/sec
> [ 4] 0.0-10.0 sec 862 MBytes 721 Mbits/sec
> [ 5] 0.0-10.0 sec 322 MBytes 270 Mbits/sec
> [ 6] 0.0-10.0 sec 1.10 GBytes 939 Mbits/sec
Could it be that with the combinations of IP addresses and port numbers
used by iperf above, it ends up with only 3 of the links being used?
According to the Linux bonding docs, xmit_hash_policy=layer3+4 uses:
((source port XOR dest port) XOR
((source IP XOR dest IP) AND 0xffff)
modulo slave count
So I guess you could plug in in the above IP addresses and port numbers
and see if you get 3 unique results?
James Pearson
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