ethernet: Reduce a runtime ntohs() in fast path

[zlei]

Summary

For untagged traffic, we always hit the check for ether_type.

No functional change intended.

MFC after: 1 week

[zlei]

sys/net/if_ethersubr.c

633

An extra space to improve readability.

[melifaro]

I’d rather avoid doing that. ntohs is fast and branchless, so I’d vote for optimizing for readability here (unless there is a measurable performance gain)

[zlei]

In D42389#967281, @melifaro wrote:

I’d rather avoid doing that.
ntohs is fast and branchless,

True indeed.

so I’d vote for optimizing for readability here (unless there is a measurable performance gain)

No measurable performance gain.

[cy]

In D42389#967281, @melifaro wrote:

I’d rather avoid doing that. ntohs is fast and branchless, so I’d vote for optimizing for readability here (unless there is a measurable performance gain)

Agrreed.