From owner-freebsd-net@FreeBSD.ORG  Thu Feb 18 15:32:54 2010
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Date: Thu, 18 Feb 2010 07:32:48 -0800
From: Patrick Mahan <mahan@mahan.org>
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Subject: Issues with em(4) device under FreeBSD 8.0
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All,

I have seen a few mentions on the mailing lists in regard to issues
with em(4) and FreeBSD 8.0 with regard to throughput.

We are also seeing similar issues on HP Proliant systems with
this HP GE interfaces.  Previously we were running FreeBSD 6.2 and
iperf was showing ~900 Mbits/sec between two directly connected
systems.  After the upgrade, iperf only shows around ~350 Mbits/sec.

This seems only to be happening on the HP's.  When we upgrade another
x86 box (privately built) we are seeing ~900 Mbits/sec even to
one of the HP systems.

I haven't seen anything yet to account for this behavior.  Has anyone
else seen similar issues?

Thanks,

Patrick