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Date: Wed, 04 Sep 2013 12:53:53 +0800
From: Julian Elischer <julian@freebsd.org>
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To: David Wolfskill <david@catwhisker.org>
Subject: Re: TSO and FreeBSD vs Linux
References: <520A6D07.5080106@freebsd.org> <5214F506.3070706@freebsd.org>
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On 9/4/13 6:49 AM, David Wolfskill wrote:
> On Tue, Sep 03, 2013 at 12:27:34PM -0700, David Wolfskill wrote:
>> ...
>> As soon as I issued "sudo net.inet.tcp.tso=0" ... the copy worked without
>> a hitch or a whine.  And I was able to copy all 117709618 bytes, not just
>> 2097152 (2^21).
> The above command should (of course) have read
>
> 	sudo sysctl net.inet.tcp.tso=0
>
> Also: I normally had the em0 NIC on the machine in question connected to
> a Netgear GS105 (5-port Gigabit switch).  In the process of
> trouble-shooting the problem with NFS writes, I bypassed that switch and
> connected the em0 NIC directly to the jack in my cube.
>
> In that configuration, the em0 NIC showed "media: Ethernet 1000baseT
> (autoselect)", while connected to the GS105, it showed "media: Ethernet
> 100baseTX (autoselect)".
>
> While the NFS write worked whether or not I had the GS105 in the path,
> it seemed ... suboptimal ... to have a NIC capable of 1000baseT
> connected to a Gigabit switch, but negotiating at 100baseTX.
>
> So I tried setting the media via "ifconfig em0 media 1000baseT"; after a
> few seconds, it finally woke back up, and now reports "media: Ethernet
> 1000baseT (1000baseT <full-duplex>)".
>
> So it appears that the em(4) driver and Intel 82578DM NIC fail to
> negotiate 1000baseT with the Netgear GS105.

yeah auto-negotiation seems a bit fragile.. not just for us either..
I often end up hardwiring it in rc.conf.
> Peace,
> david