Why it's THAT bad?
Because CPU always have to copy frames to/from the controller.
comment says card do DMA. just then it has to copy but within main memory
not PCI.
These CPU cycles could have been used in other task to give more
performance such as SSH encryption/decryption, checksum computation
etc.
3.5MB/s is less that 2500 packets/second. 50% at 200Mhz means 100000000
cycles spend on interrupt service, which is 40000 CPU cycles per packet.
That depends on your application. It would be ok for normal desktop
PCs with fast CPU but it wouldn't be acceptable on servers that
have to do lots of other processing. If you have fxp(4) or txp(4)
i know all this, but i'm asking why processing single interrupt takes
40000 CPU cycles.
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