low network speed

[James Shupe]

On 01/24/2012 11:27 PM, Eugene M. Zheganin wrote:
> Hi.
> 
> I'm suffering from low network performance on one of my FreeBSDs.
> I have an i386 8.2-RELEASE machine with an fxp(4) adapter. It's
> connected though a bunch of catalysts 2950 to another 8.2. While other
> machines in this server room using the same sequence of switches and the
> same target source server (which, btw, is equipped with an em(4) and a
> gigabit link bia catalyst 3750) show sufficient speed, this particular
> machine while using scp starts with a speed of 200 Kbytes/sec and while
> copying the file shows speed about 600-800 Kbytes/sec.
> 
> I've added this tweak to the sysctl:
> 
> net.local.stream.recvspace=196605
> net.local.stream.sendspace=196605
> net.inet.tcp.sendspace=196605
> net.inet.tcp.recvspace=196605
> net.inet.udp.recvspace=196605
> kern.ipc.maxsockbuf=2621440
> kern.ipc.somaxconn=4096
> net.inet.tcp.sendbuf_max=524288
> net.inet.tcp.recvbuf_max=524288
> 
> With these settings the copying starts at 9.5 Mbytes/sec speed, but
> then, as file is copying, drops down to 3.5 Megs/sec in about two-three
> minutes.
> 
> Is there some way to maintain 9.5 Mbytes/sec (I like this speed more) ?
> 
> 
> Thanks.
> Eugene.
> 
> P.S. This machine also runs zfs, I don't know if it's important but I
> decided to mention it.
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Test IO independently of the network and come back. ZFS takes up a lot
of memory and doesn't run amazingly well on i386. However, I doubt it
drops your IO speed to under 10MBps.

As for the network speed, try using the "-c blowfish" option and see
what speeds you get. You fail to mention the processor, and we need to
make sure it's not getting choked at the CPU during encryption before
moving to the network. Try using iperf too.

Remove that crap from sysctl and don't mess with it again.

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