Garrett D'Amore wrote: > > If I were writing a 10GbE driver, I'd use direct DMA mapping for Jumbo > frames, but I'd stick with bcopy/mcopymsg style for regular MTU frames > -- at least until someone convinced me that doing otherwise was worthwhile. >
DMA overhead depends on the architecture. Agreed that copying is almost certainly going to be faster on a SPARC system where you have an IOMMU to worry about, but DMA setup on an x86 is pretty cheap on many implementations and so mapping small packets can still be worthwhile to reduce CPU utilization. Bear in mind that for a 10G interface CPU utilization is everything. E.g. if you move from a netperf instance being able to saturate a 10G interface using a single CPU core from it taking 2 CPU cores, your benchmark performance can fall off dramatically. Paul _______________________________________________ driver-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/driver-discuss
