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Add initial support for RSS_SET, for now only operations on the indirection table are supported. Unlike the ioctl don't check if at least one parameter is being changed. This is how other ethtool-nl ops behave, so pick the ethtool-nl consistency vs copying ioctl behavior. There are two special cases here: 1) resetting the table to defaults; 2) support for tables of different size. For (1) I use an empty Netlink attribute (array of size 0). (2) may require some background. AFAICT a lot of modern devices allow allocating RSS tables of different sizes. mlx5 can upsize its tables, bnxt has some "table size calculation", and Intel folks asked about RSS table sizing in context of resource allocation in the past. The ethtool IOCTL API has a concept of table size, but right now the user is expected to provide a table exactly the size the device requests. Some drivers may change the table size at runtime (in response to queue count changes) but the user is not in control of this. What's not great is that all RSS contexts share the same table size. For example a device with 128 queues enabled, 16 RSS contexts 8 queues in each will likely have 256 entry tables for each of the 16 contexts, while 32 would be more than enough given each context only has 8 queues. To address this the Netlink API should avoid enforcing table size at the uAPI level, and should allow the user to express the min table size they expect. To fully solve (2) we will need more driver plumbing but at the uAPI level this patch allows the user to specify a table size smaller than what the device advertises. The device table size must be a multiple of the user requested table size. We then replicate the user-provided table to fill the full device size table. This addresses the "allow the user to express the min table size" objective, while not enforcing any fixed size. From Netlink perspective .get_rxfh_indir_size() is now de facto the "max" table size supported by the device. We may choose to support table replication in ethtool, too, when we actually plumb this thru the device APIs. Initially I was considering moving full pattern generation to the kernel (which queues to use, at which frequency and what min sequence length). I don't think this complexity would buy us much and most if not all devices have pow-2 table sizes, which simplifies the replication a lot. Reviewed-by: Gal Pressman <gal@nvidia.com> Link: https://patch.msgid.link/20250716000331.1378807-2-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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| ipc | ||
| kernel | ||
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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 reStructuredText 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.