Hi,
I finally had the chance to do the same throughput measurements with a db_88f3720_ddr3_modular board, which has the same 88F3720 CPU, and two phys connected to two dedicated SGMII busses (via SerDes), and it runs at 1GHz. Otherwise the same setup as above, both cores can be fully utilized using CPU affinity settings for the two SGMII related interrupts. Here are the results:
FrameSize FrameRate BitRate
64 349726 179166674
128 340851 349324332
256 313973 643659427
512 328397 1346240596
1024 237464 1946168575
1280 192286 1969230769
1400 176001 1971830985
1514 162956 1973924380
1518 162506 1973992197
So this time the GBit Ethernet gets saturated for frames >=1024bytes, and all this while staying below 55°C without a heat sink, which was really impressive 😉