2.6.12.3 network slowdown?

2.6.12.3 network slowdown?

[Howard Chu]

I just recently compiled the 2.6.12.3 kernel for my x86_64 machine
(Asus A8V motherboard); was previously running a SuSE-compiled 2.6.8
kernel (SuSE 9.2 distro). I'm now seeing extremely slow throughput on
the onboard Yukon (Marvell) ethernet interface, but only in certain
conditions. Going back to the 2.6.8 kernel shows no slowdown.

I have a few machines connected to a Linksys 5 port 10/100 hub. There
is also a Linksys WRT54G wireless router on this hub. When doing a raw 
ftp transfer of a large (600MB) file (using a Windows XP client to do a
GET) with both machines plugged into the hub, I see transfer rates only
as high as 1MB/sec initially, which quickly degrades to ~200KB/sec over 
a span of 20-30 seconds. Going the opposite direction, a PUT runs at a 
steady 7.5MB/sec.

If I unplug the Windows client and just connect via the wireless 
network, I see GETs run a steady 2.8MB/sec and PUTs run a steady 
3.2MB/sec, which is about the same as I saw with the 2.6.8 kernel, so 
that all appears normal. (But it's still odd, that adding one hop like 
this avoids the throughput degradation.)

I don't see any collisions or any other errors on the ifconfig 
statistics, just a very slow transmit rate. Does anyone recognize this 
symptom? Any suggestions on tunables to tweak, etc.? (Please cc: me 
directly when replying, thanks.)

-- 
   -- Howard Chu
   Chief Architect, Symas Corp.  http://www.symas.com
   Director, Highland Sun        http://highlandsun.com/hyc
   OpenLDAP Core Team            http://www.openldap.org/project/

Re: 2.6.12.3 network slowdown?

[Mihai Rusu]

On Wed, Jul 27, 2005 at 01:44:43AM -0700, Howard Chu wrote:
> I just recently compiled the 2.6.12.3 kernel for my x86_64 machine
> (Asus A8V motherboard); was previously running a SuSE-compiled 2.6.8
> kernel (SuSE 9.2 distro). I'm now seeing extremely slow throughput on
> the onboard Yukon (Marvell) ethernet interface, but only in certain
> conditions. Going back to the 2.6.8 kernel shows no slowdown.

You might try the other SysKonnect driver as 2.6.12 ships with 2 
different drivers for this family of NICs.

> -- 
>   -- Howard Chu
>   Chief Architect, Symas Corp.  http://www.symas.com
>   Director, Highland Sun        http://highlandsun.com/hyc
>   OpenLDAP Core Team            http://www.openldap.org/project/

-- 
Mihai RUSU                                    Email: dizzy@roedu.net
GPG : http://dizzy.roedu.net/dizzy-gpg.txt    WWW: http://dizzy.roedu.net
                       "Linux is obsolete" -- AST

Re: 2.6.12.3 network slowdown?

[Bernd Schubert]

On Wednesday 27 July 2005 12:30, Mihai Rusu wrote:
> On Wed, Jul 27, 2005 at 01:44:43AM -0700, Howard Chu wrote:
> > I just recently compiled the 2.6.12.3 kernel for my x86_64 machine
> > (Asus A8V motherboard); was previously running a SuSE-compiled 2.6.8
> > kernel (SuSE 9.2 distro). I'm now seeing extremely slow throughput on
> > the onboard Yukon (Marvell) ethernet interface, but only in certain
> > conditions. Going back to the 2.6.8 kernel shows no slowdown.
>
> You might try the other SysKonnect driver as 2.6.12 ships with 2
> different drivers for this family of NICs.
>

No, AFAIK the rewritten driver is only in 2.6.13-rc or 2.6.12-mm (also already 
in previous -mm kernel versions).

Bernd

-- 
Bernd Schubert
Physikalisch Chemisches Institut / Theoretische Chemie
Universität Heidelberg
INF 229
69120 Heidelberg
e-mail: bernd.schubert@pci.uni-heidelberg.de

Re: 2.6.12.3 network slowdown?

[Stephen Hemminger]

On Wed, 27 Jul 2005 01:44:43 -0700
Howard Chu <hyc@highlandsun.com> wrote:

> I just recently compiled the 2.6.12.3 kernel for my x86_64 machine
> (Asus A8V motherboard); was previously running a SuSE-compiled 2.6.8
> kernel (SuSE 9.2 distro). I'm now seeing extremely slow throughput on
> the onboard Yukon (Marvell) ethernet interface, but only in certain
> conditions. Going back to the 2.6.8 kernel shows no slowdown.
> 
> I have a few machines connected to a Linksys 5 port 10/100 hub. There
> is also a Linksys WRT54G wireless router on this hub. When doing a
> raw ftp transfer of a large (600MB) file (using a Windows XP client
> to do a GET) with both machines plugged into the hub, I see transfer
> rates only as high as 1MB/sec initially, which quickly degrades to
> ~200KB/sec over a span of 20-30 seconds. Going the opposite
> direction, a PUT runs at a steady 7.5MB/sec.
> 
> If I unplug the Windows client and just connect via the wireless 
> network, I see GETs run a steady 2.8MB/sec and PUTs run a steady 
> 3.2MB/sec, which is about the same as I saw with the 2.6.8 kernel, so 
> that all appears normal. (But it's still odd, that adding one hop
> like this avoids the throughput degradation.)
> 
> I don't see any collisions or any other errors on the ifconfig 
> statistics, just a very slow transmit rate. Does anyone recognize
> this symptom? Any suggestions on tunables to tweak, etc.? (Please cc:
> me directly when replying, thanks.)
> 

There a couple of possibilities, one is driver differences. SUSE ships
the SysKonnect vendor driver vs the older version in 2.6.12, and the
TCP congestion and TSO code has changed since 2.6.8.

What is the output of ethtool (ethtool -i and ethtool -k)?
Perhaps one driver has checksum offload on and the other off?
Could you get a tcpdump capture of a slow transfer?

Re: 2.6.12.3 network slowdown?

[Howard Chu]

Stephen Hemminger wrote:
> On Wed, 27 Jul 2005 01:44:43 -0700
> Howard Chu <hyc@highlandsun.com> wrote:
>> I just recently compiled the 2.6.12.3 kernel for my x86_64 machine
>> (Asus A8V motherboard); was previously running a SuSE-compiled 2.6.8
>> kernel (SuSE 9.2 distro). I'm now seeing extremely slow throughput on
>> the onboard Yukon (Marvell) ethernet interface, but only in certain
>> conditions. Going back to the 2.6.8 kernel shows no slowdown.

> There a couple of possibilities, one is driver differences. SUSE ships
> the SysKonnect vendor driver vs the older version in 2.6.12, and the
> TCP congestion and TSO code has changed since 2.6.8.

Thanks for that tip. The SuSE 2.6.8 kernel had driver version 7.04, the 
2.6.12.3 kernel had driver version 6.23. I just downloaded the current 
driver from www.syskonnect.de (8.23) and installed it and now things are 
much improved, getting around 6.8MB/sec throughput.

-- 
   -- Howard Chu
   Chief Architect, Symas Corp.  http://www.symas.com
   Director, Highland Sun        http://highlandsun.com/hyc
   OpenLDAP Core Team            http://www.openldap.org/project/