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The number of MSI-X vectors is a PCI property visible through lspci. The field is read-only and configured by the device. The mlx5 devices work in a static or dynamic assignment mode. Static assignment means that all newly created VFs have a preset number of MSI-X vectors determined by device configuration parameters. This can result in some VFs having too many or too few MSI-X vectors. Till now this has been the only means of fine-tuning the MSI-X vector count and it was acceptable for small numbers of VFs. With dynamic assignment the inefficiency of having a fixed number of MSI-X vectors can be avoided with each VF having exactly the required vectors. Userspace will provide this information while provisioning the VF for use, based on the intended use. For instance if being used with a VM, the MSI-X vector count might be matched to the CPU count of the VM. For compatibility mlx5 continues to start up with MSI-X vector assignment, but the kernel can now access a larger dynamic vector pool and assign more vectors to created VFs. Link: https://lore.kernel.org/linux-pci/20210314124256.70253-4-leon@kernel.org Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
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.