MVEBU and MVNETA driver

[gregory.clement@free-electrons.com (Gregory CLEMENT)]

On 04/19/2013 04:43 PM, Willy Tarreau wrote:
> On Fri, Apr 19, 2013 at 04:13:19PM +0200, Greg wrote:
>> Willy, thanks for your fast an accurate answer, this seems to solve the 
>> stability issue but not the performance issue.
> 
> OK.
> 
>> Please look at this strange behavior : 1 iperf will only transmit at 
>> ~100Mbps, 100 parallel iperf will transmit at ~950Mb. Reception is not 
>> an issue.
>> I'm thinking of a socket <-> txQ relationship that would limit 
>> transmission rate, but I have no idea on how this is implemented.
> 
> Strange, I have not experienced this. Yes a socket size limit could be
> the reason. Have you tried with netcat or any simple TCP server instead ?
> 

I also have this behavior:
iperf -c 192.168.0.19 -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 192.168.0.19, TCP port 5001
TCP window size: 20.7 KByte (default)
------------------------------------------------------------
[  5] local 192.168.0.37 port 48473 connected with 192.168.0.19 port 5001
[  4] local 192.168.0.37 port 5001 connected with 192.168.0.19 port 36987
[ ID] Interval       Transfer     Bandwidth
[  5]  0.0-10.0 sec   128 MBytes   107 Mbits/sec
[  4]  0.0-10.0 sec  1.07 GBytes   919 Mbits/sec

but I only need 10 thread in iperf to be close to the Gb
------------------------------------------------------------
Client connecting to 192.168.0.19, TCP port 5001
TCP window size: 20.7 KByte (default)
------------------------------------------------------------
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-10.0 sec   117 MBytes  98.2 Mbits/sec
[ 12]  0.0-10.0 sec  42.5 MBytes  35.6 Mbits/sec
[  8]  0.0-10.0 sec   131 MBytes   110 Mbits/sec
[  5]  0.0-10.0 sec   127 MBytes   107 Mbits/sec
[  3]  0.0-10.0 sec   118 MBytes  98.4 Mbits/sec
[ 10]  0.0-10.0 sec   130 MBytes   109 Mbits/sec
[  7]  0.0-10.0 sec   128 MBytes   107 Mbits/sec
[  9]  0.0-10.0 sec  83.2 MBytes  69.7 Mbits/sec
[  6]  0.0-10.0 sec   110 MBytes  92.5 Mbits/sec
[ 11]  0.0-10.0 sec   132 MBytes   110 Mbits/sec
[SUM]  0.0-10.0 sec  1.09 GBytes   936 Mbits/sec

I am not a network expert and until now we didn't try to
have the best performance the hardware can offer. We mainly
focused on features.

Regards,
-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com