From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <384D4294.E868F70B@netx4.com> Date: Tue, 07 Dec 1999 12:23:32 -0500 From: Dan Malek MIME-Version: 1.0 To: Graham Stoney CC: linuxppc-embedded@lists.linuxppc.org Subject: Re: FEC ERROR 41200000 on CLLF-860T References: <19991207070538.5A4B9118F0@elph.research.canon.com.au> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Graham Stoney wrote: > .... I notice that the fec driver in the 2.3.18 > kernel is a little different, but I haven't managed to get that kernel to run > at all yet, so I'm hanging with 2.2.13 at least for now. Yes, I have learned the importance of being able to start and shutdown network drivers (the SCC doesn't do this). The FEC also has to be configured for half/full duplex, and this we must get the link change interrupts to detect this. If you never disconnect the Ethernet, this wouldn't be necessary, but that isn't real life. The drivers are changing to accomodate all of these things. > Hmmm... performance tests are something I'm thinking about trying pretty soon! Keep in mind that both the SCC and FEC Ethernet can send and receive back-to-back packets. They also have some tuning parameters for things like backoff timers to be more friendly on the network, and for SDMA system performance. The SCC Ethernet on a 50 MHz 860 can easily maintain the theoretical network limits between 8 and 9 Mbit/sec with the TCP/IP stack. I could never understand why people use this as a "benchmark" as it is more important what you do with the data when you receive it or before you send it. This is a function of your task and the speed of the processor. There are no bounded latency guarantees or predictable behavior with Ethernet, so why try to use it like that? The SCC and FEC will send packets as fast as you can create them, and will discard packets if you can't keep up. They provide efficient burst mode DMA and off load the PPC core. What more do you need to know? -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/