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Re: ixg(4) performances

Emmanuel Dreyfus <> wrote:

> I experiment 10 GE link with ixb(4), but the result is really weak: The
> two machines have a direct link through a SFTP+ câble, and copying a file
> over NFS I get a throughput of 1.8 Mb/s, which is less than 2% of the
> link capacity. Any idea of where to look for imrovement? 

I measured TCP performance with netperf and I was able to increase
throughput up to 2.2 Gb/s using the following settings:
ifconfig ixb0 mtu 9000 tso4 ip4csum tcp4csum-tx udp4csum-tx
kern.sbmax = 67108864
kern.somaxkva = 67108864
net.inet.tcp.rfc1323 = 1
net.inet.tcp.sendspace = 2097152
net.inet.tcp.recvspace = 2097152
net.inet.tcp.recvbuf_auto = 0
net.inet.tcp.sendbuf_auto = 0

tcp4csum-rx and udp4csum-rx produces errors despite being advertised by
ifconfig capabilities line.

I do not find any way to improve further. But there is a very high
latency that may be responsible for the problem: 
PING ( 48 data bytes
64 bytes from icmp_seq=0 ttl=255 time=0.582 ms
64 bytes from icmp_seq=1 ttl=255 time=0.583 ms
64 bytes from icmp_seq=2 ttl=255 time=0.568 ms
64 bytes from icmp_seq=3 ttl=255 time=0.565 ms

This is twice what I get on gregular gigabit ethernet. Any idea of why
it is so high? >= 500 ms seems wrong on a 10GE direct link...

Emmanuel Dreyfus

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