RE: Poor 8260 FCC Ethernet performance

It's been awhile, but I seem to remember that some of the PPC drivers did
not set up full duplex properly. Make sure that fcc_fpsmr is setting
FCC_PSMR_FDE and FCC_PSMR_LPB properly. Also check to make sure that the phy
is actually set up for full duplex.


Having said all that. There is a limit to how fast the processor can forward
packets. This chip was designed to give a lot of flexibility in
connectivity. It will not forward 100Mbps of small packets, especially not
while running Linux. You could spend a lot of time and really optimize the
data path and drivers for a very significant improvement in performance. But
then you wouldn't have the flexibility of Linux.

I run a 266MHz 8265 with Linux. With a very simple kernel configuration it
can forward about 29000 pps (in on interface and out another). If I enable
iptables,nat and a few other network options, the performance drops by about
50%. If I start configuring complex iptables rule, performance will continue
to drop.

Modifying the driver to NAPI would probably help.

Dean Dayton

-----Original Message-----
From: Adisorn Ermongkonchai [mailto:aermongk@yahoo.com]
Sent: Sunday, June 06, 2004 2:01 PM
To: acurtis@onz.com
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Poor 8260 FCC Ethernet performance



Hi Allen and Linuxppc-embedded guru,

Referring to your 31 May 2002 post to LinuxPPC about
poor 8260 FCC Ether performance.  Did you figure
out why is the FCC so slow?  We have encountered this
problem as well. We use the newer MPC8270 with 400MHz
clock and 200MHz CPM speed with BCM5222 PHY.  It
ended up running at only ~5Mbps on 100Mbps Ethernet
line.  We just tried 1 FCC.

Does anyone on this post see the same problem? We use
linux 2.4.18 with PPC pqii driver (somehow the other
driver didn't seem to work for all 3 FCC's)  We
also tried on Motorola 8260 eval board and the result
is the same.  We also tried MEN Micro F6, it gave
better result from 11MBps to 30Mbps.  We also tried
just uboot to eliminate Linux out of the picture and
the result was about the same.

I was about to give up on this MPC8270 then I saw this
post so I thought I try.  I cannot believe that
Motorola would make a chip that support 3 FCC's
but can only run at this ridiculous speed.  I am
software engineer, this could be hardware.

Can anyone help me on this?  I'm about to have to
change the processor to PowerPC 4xx.

Thanks in advance.

Regards,
Adisorn Ermongkonchai

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Dayton, Dean wrote:

It's been awhile, but I seem to remember that some of the PPC drivers
did not set up full duplex properly. Make sure that fcc_fpsmr is
setting FCC_PSMR_FDE and FCC_PSMR_LPB properly. Also check to make sure
that the phy is actually set up for full duplex.

Having said all that. There is a limit to how fast the processor can
forward packets. This chip was designed to give a lot of flexibility in
connectivity. It will not forward 100Mbps of small packets, especially
not while running Linux. You could spend a lot of time and really
optimize the data path and drivers for a very significant improvement
in performance. But then you wouldn't have the flexibility of Linux.

I run a 266MHz 8265 with Linux. With a very simple kernel configuration
it can forward about 29000 pps (in on interface and out another). If I
enable iptables,nat and a few other network options, the performance
drops by about 50%. If I start configuring complex iptables rule,
performance will continue to drop.

Just to be a complete ass a 66MHz MPC885 with two FECs operating as
a virtual switch is able to keep two 100MBits ports fully saturated.
So I think that the hardware can certainly handle it.

Not under linux though.

quoted

-----Original Message-----
From: Adisorn Ermongkonchai [mailto:aermongk@yahoo.com]
Sent: Sunday, June 06, 2004 2:01 PM
Subject: Poor 8260 FCC Ethernet performance

Referring to your 31 May 2002 post to LinuxPPC about poor 8260 FCC
Ether performance. Did you figure out why is the FCC so slow? We have
encountered this problem as well. We use the newer MPC8270 with 400MHz
clock and 200MHz CPM speed with BCM5222 PHY. It ended up running at
only ~5Mbps on 100Mbps Ethernet line. We just tried 1 FCC.

Does anyone on this post see the same problem? We use linux 2.4.18
with PPC pqii driver (somehow the other driver didn't seem to work for
all 3 FCC's) We also tried on Motorola 8260 eval board and the result
is the same. We also tried MEN Micro F6, it gave better result from
11MBps to 30Mbps. We also tried just uboot to eliminate Linux out of
the picture and the result was about the same.

I was about to give up on this MPC8270 then I saw this post so I
thought I try. I cannot believe that Motorola would make a chip that
support 3 FCC's but can only run at this ridiculous speed. I am
software engineer, this could be hardware.

Can anyone help me on this? I'm about to have to change the processor
to PowerPC 4xx.

Regards

Pantelis

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/