netmap: add load balancer program

[vmaffione]

Summary

Add the lb program, which is able to load-balance input traffic received from a netmap port over M groups, with N netmap pipes in each group.
Each received packet is forwarded to one of the pipes chosen from each group (using an L3/L4 connection-consistent hash function).
This also adds a man page for lb and some cross-references in related man pages.

Test Plan

Man page tested with igor and mandoc -Tlint.
Used in production environments for at least a year.

[vmaffione]

This patch depends on https://reviews.freebsd.org/D17698 , because of the changes to ctrs.h.

[vmaffione]

Minor fixes to the man pages.

[bcr]

Approved!

[0mp]

Most of my comments are just suggestions. :)

tools/tools/netmap/bridge.8

74 ↗

(On Diff #49721)

Remember to bump the date in this manual page as well.

tools/tools/netmap/lb.8

57 ↗

(On Diff #49721)

mdoc renders two spaces after the closing bracket.

I opened a bug report for that: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=232779

59 ↗

(On Diff #49721)

How about:

.It Fl p Ar name Ns Cm : Ns Ar number | number

: is not an argument, it is a command modifier.

64 ↗

(On Diff #49721)

Do you think that we would benefit from quoting those names?

will be called
.Dq Ar name Ns Em }0
to
.Dq Ar name No Ns Em } Ns Aq Ar number No - 1 .

72 ↗

(On Diff #49721)

Typo: Fl p

[vmaffione]

Implemented the changes suggested by the reviewers.

[vmaffione]

Is the man page looking better now?

[0mp]

Just on thing on my side. Sorry about that!

Otherwise, LGTM.

tools/tools/netmap/lb.8

59 ↗

(On Diff #49759)

I'm sorry: Cm has to be escaped here to apply to ::

.It Fl p Ar name Ns Cm \&: Ns Ar number | number

Then you'll see that : is in fact bold.

[vmaffione]

Thanks! I did not get you wanted the ":" bold.

[gnn]

Approved by mentor

[vmaffione]

Thanks for the review. However, I need to commit this https://reviews.freebsd.org/D17698 first.