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Update MTU post

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Neil Alexander 2018-07-13 10:34:11 +01:00
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_posts/2018-07-13-about-mtu.md
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@ -24,13 +24,14 @@ operating system will have to fragment the packet down into smaller ones before
sending out onto the wire.
With a smaller MTU, you will be forced to re-send the IP headers (and possibly
other headers) along with every single packet. Those are not only wasted bytes
on the wire, but every packet likely requires a new set of system calls to
handle. In the case of Yggdrasil, we rely on system calls not just for socket
operations but also for TUN/TAP. Each system call requires a context switch,
which is a slow operation. On embedded platforms, this can be a real killer for
performance - in fact, on an EdgeRouter X, context switching for the TUN/TAP
adapter is a greater bottleneck than the cryptographic algorithms themselves!
other headers) far more often with every single packet. Those are not only
wasted bytes on the wire, but every packet likely requires a new set of system
calls to handle. In the case of Yggdrasil, we rely on system calls not just for
socket operations but also for TUN/TAP. Each system call requires a context
switch, which is a slow operation. On embedded platforms, this can be a real
killer for performance - in fact, on an EdgeRouter X, context switching for the
TUN/TAP adapter is a greater bottleneck than the cryptographic algorithms
themselves!
### Selecting TCP instead of UDP