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Ido Schimmel says: ==================== mlxsw: Remove size limitations on egress descriptor buffer Petr says: Spectrum machines have two resources related to keeping packets in an internal buffer: bytes (allocated in cell-sized units) for packet payload, and descriptors, for keeping headers. Currently, mlxsw only configures the bytes part of the resource management. Spectrum switches permit a full parallel configuration for the descriptor resources, including port-pool and port-TC-pool quotas. By default, these are all configured to use pool 14, with an infinite quota. The ingress pool 14 is then infinite in size. However, egress pool 14 has finite size by default. The size is chip dependent, but always much lower than what the chip actually permits. As a result, we can easily construct workloads that exhaust the configured descriptor limit. Going forward, mlxsw will have to fix this issue properly by maintaining descriptor buffer sizes, TC bindings, and quotas that match the architecture recommendation. Short term, fix the issue by configuring the egress descriptor pool to be infinite in size as well. This will maintain the same configuration philosophy, but will unlock all chip resources to be usable. In this patchset, patch #1 first adds the "desc" field into the pool configuration register. Then in patch #2, the new field is used to configure both ingress and egress pool 14 as infinite. In patches #3 and #4, add a selftest that verifies that a large burst can be absorbed by the shared buffer. This test specifically exercises a scenario where descriptor buffer is the limiting factor and the test fails without the above patches. ==================== Link: https://lore.kernel.org/r/20220502084926.365268-1-idosch@nvidia.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> |
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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.