Re: [PATCH v2] tcp: splice as many packets as possible at once

Roland Dreier
2009-02-04T19:19:40Z

> And the arbitrary choice of 9k for jumbo frames was total crap too.
> It's clear that no hardware designer was involved in the process.
> They have to stuff 16kB of RAM on a NIC to use only 9. And we need
> to allocate 3 pages for slightly more than 2. 7.5 kB would have been
> better in this regard.

9K was not totally arbitrary. The CRC used for checksumming ethernet
packets has a probability of undetected errors that goes up about
11-thousand something bytes. So the real limit is ~11000 bytes, and I
believe ~9000 was chosen to be able to carry 8K NFS payloads + all XDR
and transport headers without fragmentation.

- R.