We actually opened an issue with IBM over this. Here's what I got back:
Action Taken...: The ethtool utility is not supported with all device
drivers as noted in the man page. It's very typical that for an
gigabit NIC (especially a fiber connection) will not have a valid
speed reported or no speed reported at all. To some degree it makes a
bit of sense as a gigabit card is exactly that, 1GB. That is you can't
tell a 1GB FIBER card to run at 10MB. Granted what gets reported by
ethtool (really what th device driver is returning is mis-leading).
Here is another example .. a very simple Tigon3 GB NIC, note the
speed it reported as Unknown!
[EMAIL PROTECTED] ~]# ethtool eth0
Settings for eth0:
Supported ports: [ FIBRE ]
Supported link modes: 1000baseT/Half 1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 1000baseT/Half 1000baseT/Full
Advertised auto-negotiation: Yes
Speed: Unknown! (0)
Duplex: Half
Port: FIBRE
mii-tool is only valid for mii compatable NIC cards.
If the goal is to do some performance testing, then the best method
is to use the netperf tools. ( see http://www.netperf.org) Another
simple test is using dd and ftp, for example:
# ftp <hostname_of_server>
ftp> bin
ftp> put "| dd if=/dev/zero bs=32k count=10000" /dev/null
Using either of these tools should confirm that the NICS are
transfering far faster the 10MB.
So in other words, the gigabit OSA can only run at a gigabit, the tools
are useless for this application, and the only way to be sure about the
throughput is to measure it.
-----Original Message-----
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of
Mark Post
Sent: Monday, September 29, 2008 12:14 PM
To: [email protected]
Subject: Re: [LINUX-390] Gigabit interface on Linux?
>>> On 9/29/2008 at 12:02 PM, in message
<[EMAIL PROTECTED]>, Scott
Rohling
<[EMAIL PROTECTED]> wrote:
> On RHEL5.2 -- we're using mii-tools and seeing that the ethernet
interface
> is set to 100mbs -- the OSA is set to gigabit - and we're wondering
if
> something special needs to be done to set it to gigabit speeds..
Using
> 'ethtool=' doesn't seem to work on Linux (s390x linux)..
I'm amazed that mii-tools returns anything at all.
> This is on a VSWITCH -- everything works fine except the reported
speed...
> Any ideas?
Since the interface that mii-tools is reporting on is a virtual one,
having nothing to do with any real hardware, I would say ignore it.
Mark Post
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