From: David Ahern <dsahern@gmail.com>
Date: Sat, 14 Nov 2020 02:48:52 +0000 (-0700)
Subject: Merge branch 'dcb-tool' into next
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=1ed00380b0854a61d0c40856720fb3065eb117d4;hp=-c;p=mirror_iproute2.git

Merge branch 'dcb-tool' into next

Petr Machata  says:
====================

The Linux DCB interface allows configuration of a broad range of
hardware-specific attributes, such as TC scheduling, flow control, per-port
buffer configuration, TC rate, etc.

Currently a common libre tool for configuration of DCB is OpenLLDP. This
suite contains a daemon that uses Linux DCB interface to configure HW
according to the DCB TLVs exchanged over an interface. The daemon can also
be controlled by a client, through which the user can adjust and view the
configuration. The downside of using OpenLLDP is that it is somewhat
heavyweight and difficult to use in scripts, and does not support
extensions such as buffer and rate commands.

For access to many HW features, one would be perfectly fine with a
fire-and-forget tool along the lines of "ip" or "tc". For scripting in
particular, this would be ideal. This author is aware of one such tool,
mlnx_qos from Mellanox OFED scripts collection[1].

The downside here is that the tool is very verbose, the command line
language is awkward to use, it is not packaged in Linux distros, and
generally has the appearance of a very vendor-specific tool, despite not
being one.

This patchset addresses the above issues by providing a seed of a clean,
well-documented, easily usable, extensible fire-and-forget tool for DCB
configuration:

    # dcb ets set dev eni1np1 \
                  tc-tsa all:strict 0:ets 1:ets 2:ets \
		  tc-bw all:0 0:33 1:33 2:34

    # dcb ets show dev eni1np1 tc-tsa tc-bw
    tc-tsa 0:ets 1:ets 2:ets 3:strict 4:strict 5:strict 6:strict 7:strict
    tc-bw 0:33 1:33 2:34 3:0 4:0 5:0 6:0 7:0

    # dcb ets set dev eni1np1 tc-bw 1:30 2:37

    # dcb -j ets show dev eni1np1 | jq '.tc_bw[2]'
    37

The patchset proceeds as follows:

- Many tools in iproute2 have an option to work in batch mode, where the
  commands to run are given in a file. The code to handle batching is
  largely the same independent of the tool in question. In patch #1, add a
  helper to handle the batching, and migrate individual tools to use it.

- A number of configuration options come in a form of an on-off switch.
  This in turn can be considered a special case of parsing one of a given
  set of strings. In patch #2, extract helpers to parse one of a number of
  strings, on top of which build an on-off parser.

  Currently each tool open-codes the logic to parse the on-off toggle. A
  future patch set will migrate instances of this code over to the new
  helpers.

- The on/off toggles from previous list item sometimes need to be dumped.
  While in the FP output, one typically wishes to maintain consistency with
  the command line and show actual strings, "on" and "off", in JSON output
  one would rather use booleans. This logic is somewhat annoying to have to
  open-code time and again. Therefore in patch #3, add a helper to do just
  that.

- The DCB tool is built on top of libmnl. Several routines will be
  basically the same in DCB as they are currently in devlink. In patches
  #4-#6, extract them to a new module, mnl_utils, for easy reuse.

- Much of DCB is built around arrays. A syntax similar to the iplink_vlan's
  ingress-qos-map / egress-qos-map is very handy for describing changes
  done to such arrays. Therefore in patch #7, extract a helper,
  parse_mapping(), which manages parsing of key-value arrays. In patch #8,
  fix a buglet in the helper, and in patch #9, extend it to allow setting
  of all array elements in one go.

- In patch #10, add a skeleton of "dcb", which contains common helpers and
  dispatches to subtools for handling of individual objects. The skeleton
  is empty as of this patch.

  In patch #11, add "dcb_ets", a module for handling of specifically DCB
  ETS objects.

  The intention is to gradually add handlers for at least PFC, APP, peer
  configuration, buffers and rates.

[1] https://github.com/Mellanox/mlnx-tools/tree/master/ofed_scripts

====================

Signed-off-by: David Ahern <dsahern@gmail.com>
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1ed00380b0854a61d0c40856720fb3065eb117d4