Gianfar is slower than fcc_enet on MPC8541 ???

[Laurent Lagrange]

Hello,

I work on a cutom MPC8541 board with Linux 2.6.9.
The kernel activates the L1 cache (instructions and data)
and the L2 cache (entirely used as cache and not as sram).

I configure 
1 FCC (FCC1),
2 TSECs with or without NAPI (no effect) but without stashing in L2 sram.
All PHYs are automatically configured in 100MB full duplex.

        eth0: Gianfar Ethernet Controller Version 1.1, 00:10:cd:48:48:e0
        eth0: Running with NAPI disabled
        eth0: 64/64 RX/TX BD ring size
        eth1: Gianfar Ethernet Controller Version 1.1, 00:10:cd:48:48:e1
        eth1: Running with NAPI disabled
        eth1: 64/64 RX/TX BD ring size
        eth2: FCC ENET Version custom, 00:10:cd:48:48:e2

Then I launch 3 simple TCP servers, one on each ports.

>From remote machines I runs 3 TCP clients.
The client sends messages of 1000 bytes, 
The server receives and echoes the message
The client receives the echoed message, check the content
and sends a new message again.

The result is that the 2 TSECs are 2 times slower than the FCC.

If I run a "top" application on the board, I use less than 10% of the CPU
Each port consumes about 1/3 of the CPU.

Any idea on how to configure the gianfar driver ?

Thanks
Laurent