em0 performance subpar

[Steven Hartland]

You said your testing with iperf, what settings are you using?

Flow control is not flowtable no, which could still result in
a switch "issue" if linux and freebsd are setting different
values by default, similarly with duplex / speed, I would recommend
autoneg if your not already using.

Have you tried without tso, rxcsum, txcsum & lro disabled?


----- Original Message ----- 
From: "Adam Stylinski" <kungfujesus06 at gmail.com>
To: "Steven Hartland" <killing at multiplay.co.uk>
Cc: <freebsd-net at freebsd.org>
Sent: Thursday, April 28, 2011 3:45 PM
Subject: Re: em0 performance subpar

I was using the default value for maxsockbuf, doesn't seem to hurt or help.  The only value you've listed that I didn't have 
tweaked to a comparable value already was the nmbclusters, changing it seems to have no effect, though.  vmstat -i should display 
my interrupts, which I don't think are particularly high.  I am most definitely not CPU bound (utilization shows no hot CPUs), I 
have 16GB of memory and plenty allocated to the kernel, and I believe flow control is enabled (should it not be?):
net.inet.flowtable.enable: 1

It's a 16 port netgear gigabit prosafe switch, and it's not likely to be the problem (like I said, the Linux hosts have no issues 
with the same card).


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