forked from Minki/linux
mainlining shenanigans
18e9a40732
Ido Schimmel says: ==================== mlxsw: Refactor headroom management Petr says: On Spectrum, port buffers, also called port headroom, is where packets are stored while they are parsed and the forwarding decision is being made. For lossless traffic flows, in case shared buffer admission is not allowed, headroom is also where to put the extra traffic received before the sent PAUSE takes effect. Another aspect of the port headroom is the so called internal buffer, which is used for egress mirroring. Linux supports two DCB interfaces related to the headroom: dcbnl_setbuffer for configuration, and dcbnl_getbuffer for inspection. In order to make it possible to implement these interfaces, it is first necessary to clean up headroom handling, which is currently strewn in several places in the driver. The end goal is an architecture whereby it is possible to take a copy of the current configuration, adjust parameters, and then hand the proposed configuration over to the system to implement it. When everything works, the proposed configuration is accepted and saved. First, this centralizes the reconfiguration handling to one function, which takes care of coordinating buffer size changes and priority map changes to avoid introducing drops. Second, the fact that the configuration is all in one place makes it easy to keep a backup and handle error path rollbacks, which were previously hard to understand. Patch #1 introduces struct mlxsw_sp_hdroom, which will keep port headroom configuration. Patch #2 unifies handling of delay provision between PFC and PAUSE. From now on, delay is to be measured in bytes of extra space, and will not include MTU. PFC handler sets the delay directly from the parameter it gets through the DCB interface. For PAUSE, MLXSW_SP_PAUSE_DELAY is converted to have the same meaning. In patches #3-#5, MTU, lossiness and priorities are gradually moved over to struct mlxsw_sp_hdroom. In patches #6-#11, handling of buffer resizing and priority maps is moved from spectrum.c and spectrum_dcb.c to spectrum_buffers.c. The API is gradually adapted so that struct mlxsw_sp_hdroom becomes the main interface through which the various clients express how the headroom should be configured. Patch #12 is a small cleanup that the previous transformation made possible. In patch #13, the port init code becomes a boring client of the headroom code, instead of rolling its own thing. Patches #14 and #15 move handling of internal mirroring buffer to the new headroom code as well. Previously, this code was in the SPAN module. This patchset converts the SPAN module to another boring client of the headroom code. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.