> -----Original Message-----
> From: Ben Greear [mailto:[email protected]]
> Sent: Tuesday, December 04, 2012 5:35 PM
> To: Skidmore, Donald C
> Cc: e1000-devel list
> Subject: Re: [E1000-devel] Question on ixgbe and bus speed/width.
> 
> On 12/04/2012 05:27 PM, Skidmore, Donald C wrote:
> >> -----Original Message-----
> >> From: Ben Greear [mailto:[email protected]]
> >> Sent: Tuesday, December 04, 2012 5:19 PM
> >> To: e1000-devel list
> >> Subject: [E1000-devel] Question on ixgbe and bus speed/width.
> >>
> >> I'm testing a 4 port 10G NIC (ixgbe) in a pci-e gen3 motherboard.
> >>
> >> On most boots, all 4 ports show 5GT/s x8 bus, but on at least one
> >> boot, two of the NICs came up as 5GT/s and x4.  It took a long time
> >> to notice this was the problem that caused poor performance.
> >>
> >> Is there a way in ethtool, or another standard-ish way to query the
> >> bus speed and width?
> >>
> >>
> >> Thanks,
> >> Ben
> >
> > Looking for something like 'lspci -vv'?
> 
> That shows some 'Capabilities' mentioning 5GT/s, but is that just what the
> NIC is theoretically capable of, or it's current negotiated speed?
> 

My understanding was it displayed it's current negotiated speed and lanes used. 
 

For what it is worth the ixgbe driver should log a warning during probe if we 
don't get the PCIe link we need for full speed.  Although it is more complex 
with the 4 port as there the switch on the NIC in the way.

Thanks,
-Don


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