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Ido Schimmel says: ==================== mlxsw: Multi-level qdisc offload Petr says: Currently, mlxsw admits for offload a suitable root qdisc, and its children. Thus up to two levels of hierarchy are offloaded. Often, this is enough: one can configure TCs with RED and TCs with a shaper on, and can even see counters for each TC by looking at a qdisc at a sufficiently shallow position. While simple, the system has obvious shortcomings. It is not possible to configure both RED and shaping on one TC. It is not possible to place a PRIO below root TBF, which would then be offloaded as port shaper. FIFOs are only offloaded at root or directly below, which is confusing to users, because RED and TBF of course have their own FIFO. This patch set lifts assumptions that prevent offloading multi-level qdisc trees. In patch #1, offload of a graft operation is added to TBF. Grafts are issued as another qdisc is linked to the qdisc in question, and give drivers a chance to react to the linking. The absence of this event was not a major issue so far, because TBF was not considered classful, which changes with this patchset. The codebase currently assumes that ETS and PRIO are the only classful qdiscs. The following patches gradually lift this assumption. In patch #2, calculation of traffic class and priomap of a qdisc is fixed. Patch #3 fixes handling of future FIFOs. Child FIFO qdiscs may be created and notified before their parent qdisc exists and therefore need special handling. Patches #4, #5 and #6 unify, respectively, child destruction, child grafting, and cleanup of statistics. Patch #7 adds a function that validates whether a given qdisc topology is offloadable. Finally in patch #8, TBF and RED become classful. At this point, FIFO qdiscs grafted to an offloaded qdisc should always be offloaded. Patch #9 adds a selftest to verify some offloadable and unoffloadable qdisc trees. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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.