Hello, I'm currently trying to implement NAPI for the FEC on the MPC5200 to solve the well known problem, that network packet storms can cause interrupt flooding, which may totally block the system. The NAPI implementation, in principle, is straight forward and works well under normal and moderate network load. It just calls disable_irq() in the receive interrupt handler to defer packet processing to the NAPI poll callback, which calls enable_irq() when it has processed all packets. Unfortunately, under heavy network load (packet storm), problems show up:
- With DENX 2.4.25, the Bestcomm RX task gets and remains stopped after a while under additional system load. I have no idea how and when Bestcom tasks are stopped. In the auto-start mode, the firmware should poll forever for the next free descriptor block. - With 2.6.31-rc2, the RFIFO error occurs quickly which does reset the FEC and Bestcomm (unfortunately, this does trigger an oops because it's called from the interrupt context, but that's another issue). I'm realized that working with Bestcomm is a pain :-( but so far I have little knowledge of the Bestcomm limitations and quirks. Any idea what might go wrong or how to implement NAPI for that FEC properly. TIA, Wolfgang. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
