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Comment by kalleboo | Hacker News Reader

> unique challenge here involves handling IP packets (around 1500 bytes each) at data rates of between 1 and 8 Gigabits per second

This reminded me of something. At this point it seems like Jumbo frames are never going to be widely adopted, are they? Otherwise this seems like the perfect application - massive datarates, controlled hardware/software, high-quality wiring...

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Working with Mellanox cards for a few weeks; the MTU matters a lot. The difference between an iperf test measuring 14 Gbits/s on MTU 1500 vs. 40 Gbits/s on MTU 9000.

We got a couple of Connect-X5 cards, which allow switchless connections, akin to a ring topology. A lot of neat things, at just stupid line speeds, and latency levels I haven't seen in software, ever.

Interesting. I bought a "real" netgear switch a few years back (geared to the small business market) and did some tests with jumbo frames enabled, and saw only a slightly under 10% difference in performance pushing 10GB files from my laptop to my NAS.

Everything else was consumer level though. I did ensure that everything was flipped to jumbo frames. I/O shouldn't have been the factor since it was SSD on both sides.

Mellanox has some interesting stuff, I used to work with it back in my HFT days.

Not sure why this would be. Mellanox can do line rate on 40G at 1500 using dpdk easily.

For my home LAN the problem with Jumbo packets is that it seems there isn't a standard size that all NICs support. I have several machines that support 9000 bytes, some 9014 bytes, some only up to 4000 bytes. So I haven't been able to get the whole network on a single MTU. At least this was a case a few years ago.

Jumbo frames are limited in the improvement over 1500 octet frames, around 9000 bytes. That's still too small. I think NIC offload mechanisms already handle bigger chunks of data and let the OS TX/RX 64k or more at a time.

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