netdev - RE: e1000 driver and samba

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Date:	Mon, 17 Sep 2007 14:01:07 -0700
From:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
To:	"L F" <lfabio.linux@...il.com>,
	"Kok, Auke-jan H" <auke-jan.h.kok@...el.com>
Cc:	"James Chapman" <jchapman@...alix.com>, <netdev@...r.kernel.org>
Subject: RE: e1000 driver and samba

L F wrote:
> On 9/17/07, Kok, Auke <auke-jan.h.kok@...el.com> wrote:
>> The statistic we were looking at _will_ increase when running in
>> half duplex, but if it increases when running in full duplex might
>> indicate a hardware failure. Probably you have fixed the issue with
>> the CAT6 cable. 
> Uhm, 'fixed' may be premature: I restarted the machine and with 22
> hours uptime I am getting:
> tx_deferred_ok: 36254
> 
>> Can you run this new configuration with the old cable? that would
>> eliminate the cable (or not)
> I most certainly can. This seems to have gotten worse by a factor or
> 100 or more.. so am I to suspect the new cable?
> 
>> A single port failure on a switch can also happen, and samba is
>> definately 
>> a good test for defective hardware. I cannot rule out anything from
>> the information we have gotten yet.
> True, but I tried changing the switch ports with little change.
> Putting a client on the same switch port yielded no errors on the
> client, although unfortunately I don't have ethtool statistics on XP.
> The switch, btw, is a fairly generic GS108 from Netgear (there
> actually are two).

it may be not well documented, but the hardware has several states that
it can get into that can cause tx_deferred counter to increment.  None
of them are fatal to traffic, it is mainly an informational statistic.

in this case it is in the "due to receiving flow control; tx is paused"
state...

he has 488 rx flow control xoff/xon, which means the switch is being
overloaded and sending flow control, or the switch is passing through
flow control packets (which it should not since they are multicast) and
(some) client is overloaded.

can you turn off flow control at the server?  ethtool -A ethX rx off tx
off or load the driver with parameter FlowControl=0  With the 7.6.5
driver at least you'll get confirmation of the flow control change on
the "Link Up:" line.

Jesse
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