MFC r340279

netmap: add load balancer program

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.

Reviewed by: bcr, 0mp
Approved by: gnn (mentor)
Differential Revision: https://reviews.freebsd.org/D17735

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.

This new version of netmap brings you the following:

- netmap pipes, providing bidirectional blocking I/O while moving
100+ Mpps between processes using shared memory channels
(no mistake: over one hundred million. But mind you, i said
*moving* not *processing*);

- kqueue support (BHyVe needs it);

- improved user library. Just the interface name lets you select a NIC,
host port, VALE switch port, netmap pipe, and individual queues.
The upcoming netmap-enabled libpcap will use this feature.

- optional extra buffers associated to netmap ports, for applications
that need to buffer data yet don't want to make copies.

- segmentation offloading for the VALE switch, useful between VMs.

and a number of bug fixes and performance improvements.

My colleagues Giuseppe Lettieri and Vincenzo Maffione did a substantial
amount of work on these features so we owe them a big thanks.

There are some external repositories that can be of interest:

https://code.google.com/p/netmap
our public repository for netmap/VALE code, including
linux versions and other stuff that does not belong here,
such as python bindings.

https://code.google.com/p/netmap-libpcap
a clone of the libpcap repository with netmap support.
With this any libpcap client has access to most netmap
feature with no recompilation. E.g. tcpdump can filter
packets at 10-15 Mpps.

https://code.google.com/p/netmap-ipfw
a userspace version of ipfw+dummynet which uses netmap
to send/receive packets. Speed is up in the 7-10 Mpps
range per core for simple rulesets.

Both netmap-libpcap and netmap-ipfw will be merged upstream at some
point, but while this happens it is useful to have access to them.

And yes, this code will be merged soon. It is infinitely better
than the version currently in 10 and 9.

MFC after: 3 days

netmap_user.h:
add separate rx/tx ring indexes
add ring specifier in nm_open device name

netmap.c, netmap_vale.c
more consistent errno numbers

netmap_generic.c
correctly handle failure in registering interfaces.

tools/tools/netmap/
massive cleanup of the example programs
(a lot of common code is now in netmap_user.h.)

nm_util.[ch] are going away soon.
pcap.c will also go when i commit the native netmap support for libpcap.

Bring in a number of new features, mostly implemented by Michio Honda:

- the VALE switch now support up to 254 destinations per switch,
unicast or broadcast (multicast goes to all ports).

- we can attach hw interfaces and the host stack to a VALE switch,
which means we will be able to use it more or less as a native bridge
(minor tweaks still necessary).
A 'vale-ctl' program is supplied in tools/tools/netmap
to attach/detach ports the switch, and list current configuration.

- the lookup function in the VALE switch can be reassigned to
something else, similar to the pf hooks. This will enable
attaching the firewall, or other processing functions (e.g. in-kernel
openvswitch) directly on the netmap port.

The internal API used by device drivers does not change.

Userspace applications should be recompiled because we
bump NETMAP_API as we now use some fields in the struct nmreq
that were previously ignored -- otherwise, data structures
are the same.

Manpages will be committed separately.

update the netmap example programs merging some common code in nm_util.c

pkt-gen now implements several functions (unlimited transmit, receive,
ping-pong) and can operate on a 'tap' device.

Bring in support for netmap, a framework for very efficient packet
I/O from userspace, capable of line rate at 10G, see

http://info.iet.unipi.it/~luigi/netmap/

At this time I am bringing in only the generic code (sys/dev/netmap/
plus two headers under sys/net/), and some sample applications in
tools/tools/netmap. There is also a manpage in share/man/man4 [1]

In order to make use of the framework you need to build a kernel
with "device netmap", and patch individual drivers with the code
that you can find in

sys/dev/netmap/head.diff

The file will go away as the relevant pieces are committed to
the various device drivers, which should happen in a few days
after talking to the driver maintainers.

Netmap support is available at the moment for Intel 10G and 1G
cards (ixgbe, em/lem/igb), and for the Realtek 1G card ("re").
I have partial patches for "bge" and am starting to work on "cxgbe".
Hopefully changes are trivial enough so interested third parties
can submit their patches. Interested people can contact me
for advice on how to add netmap support to specific devices.

CREDITS:
Netmap has been developed by Luigi Rizzo and other collaborators
at the Universita` di Pisa, and supported by EU project CHANGE
(http://www.change-project.eu/)
The code is distributed under a BSD Copyright.

[1] In my opinion is a bad idea to have all manpage in one directory.
We should place kernel documentation in the same dir that contains
the code, which would make it much simpler to keep doc and code
in sync, reduce the clutter in share/man/ and incidentally is
the policy used for all of userspace code.
Makefiles and doc tools can be trivially adjusted to find the
manpages in the relevant subdirs.