Poor 8260 FCC Ethernet performance

[Pantelis Antoniou]

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.

>>-----Original Message-----
>>From: Adisorn Ermongkonchai [mailto:aermongk at 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

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