My guess is that you are measuring latency. By default, interrupt coalescing is on, and used to be set to very poor default values. In drivers/net/gianfar.h, change the defaults to look like this:
#define DEFAULT_TX_COALESCE 1 #define DEFAULT_TXCOUNT 16 #define DEFAULT_TXTIME 4 #define DEFAULT_RX_COALESCE 1 #define DEFAULT_RXCOUNT 16 #define DEFAULT_RXTIME 4 The problem was that the timeout was quite long, so a small number of packets would have to wait a whole millisecond (or more!) to get processed. While it wouldn't affect bandwidth tests, which send many packets, it would affect a simple test like ping. If you don't feel like recompiling the kernel, you can use ethtool to change the timeout values. On Feb 14, 2006, at 09:26, Laurent Lagrange wrote: > > 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 > > > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded at ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded
