Re: IP performance question
Hi.
On Sun, 24 May 2015 13:47:48 +0200
Petter Adsen <petter@synth.no> wrote:
> On Sun, 24 May 2015 13:26:52 +0200
> Petter Adsen <petter@synth.no> wrote:
> > Thanks to you, I now get ~880Mbps, which is a lot better. It seems
> > increasing the MTU was what had the most effect, so I won't bother
> > with TCP window size.
>
> Now, this is a little odd:
>
> petter@monster:/etc$ iperf -i 1 -c fenris -r
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size: 85.3 KByte (default)
> ------------------------------------------------------------
> ------------------------------------------------------------
> Client connecting to fenris, TCP port 5001
> TCP window size: 280 KByte (default)
> ------------------------------------------------------------
> [ 5] local 192.168.0.105 port 49636 connected with 192.168.0.103 port
> 5001 [ ID] Interval Transfer Bandwidth
> [ 5] 0.0- 1.0 sec 104 MBytes 875 Mbits/sec
> [ 5] 1.0- 2.0 sec 97.8 MBytes 820 Mbits/sec
> [ 5] 2.0- 3.0 sec 104 MBytes 868 Mbits/sec
> [ 5] 3.0- 4.0 sec 104 MBytes 876 Mbits/sec
> [ 5] 4.0- 5.0 sec 104 MBytes 876 Mbits/sec
> [ 5] 5.0- 6.0 sec 83.0 MBytes 696 Mbits/sec
> [ 5] 6.0- 7.0 sec 105 MBytes 879 Mbits/sec
> [ 5] 7.0- 8.0 sec 104 MBytes 875 Mbits/sec
> [ 5] 8.0- 9.0 sec 105 MBytes 884 Mbits/sec
> [ 5] 9.0-10.0 sec 104 MBytes 877 Mbits/sec
> [ 5] 0.0-10.0 sec 1016 MBytes 852 Mbits/sec
> [ 4] local 192.168.0.105 port 5001 connected with 192.168.0.103 port
> 34815 [ 4] 0.0- 1.0 sec 98.5 MBytes 826 Mbits/sec
> [ 4] 1.0- 2.0 sec 98.5 MBytes 826 Mbits/sec
> [ 4] 2.0- 3.0 sec 97.4 MBytes 817 Mbits/sec
> [ 4] 3.0- 4.0 sec 98.0 MBytes 822 Mbits/sec
> [ 4] 4.0- 5.0 sec 98.5 MBytes 827 Mbits/sec
> [ 4] 5.0- 6.0 sec 98.1 MBytes 823 Mbits/sec
> [ 4] 6.0- 7.0 sec 98.6 MBytes 827 Mbits/sec
> [ 4] 7.0- 8.0 sec 98.5 MBytes 826 Mbits/sec
> [ 4] 8.0- 9.0 sec 98.5 MBytes 827 Mbits/sec
> [ 4] 9.0-10.0 sec 98.5 MBytes 826 Mbits/sec
> [ 4] 0.0-10.0 sec 984 MBytes 825 Mbits/sec
>
> I have run it many times, and the results are consistently ~50Mbps
> lower in the other direction. MTU is set to 7152 on both hosts, but the
> window size is back to the default values (212992).
Hmm. A first thought is that you have a different TCP window size on
client and a server.
And a second thought is that you probably should check interface
statistics with ifconfig or 'ip -s link show'. Every packet that is
not RX or TX means trouble.
Reco
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