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Saeed Mahameed says: ==================== mlx5 xsk updates part3 2022-09-30 The gist of this 4 part series is in this patchset's last patch This series contains performance optimizations. XSK starts using the batching allocator, and XSK data path gets separated from the regular RX, allowing to drop some branches not relevant for non-XSK use cases. Some minor optimizations for indirect calls and need_wakeup are also included. Other than that, this series adds a few features to the mlx5e implementation of XSK: 1. XDP metadata support on XSK RQs. 2. RSS contexts support for XSK RQs. 3. Some other optimizations 4. Last but not least, change the queuing scheme, so that XSK RQs no longer use higher indices, but replace the regular RQs. Maxim Says: ========== In the initial implementation of XSK in mlx5e, XSK RQs coexisted with regular RQs in the same channel. The main idea was to allow RSS work the same for regular traffic, without need to reconfigure RSS to exclude XSK queues. However, this scheme didn't prove to be beneficial, mainly because of incompatibility with other vendors. Some tools don't properly support using higher indices for XSK queues, some tools get confused with the double amount of RQs exposed in sysfs. Some use cases are purely XSK, and allocating the same amount of unused regular RQs is a waste of resources. This commit changes the queuing scheme to the standard one, where XSK RQs replace regular RQs on the channels where XSK sockets are open. Two RQs still exist in the channel to allow failsafe disable of XSK, but only one is exposed at a time. The next commit will achieve the desired memory save by flushing the buffers when the regular RQ is unused. As the result of this transition: 1. It's possible to use RSS contexts over XSK RQs. 2. It's possible to dedicate all queues to XSK. 3. When XSK RQs coexist with regular RQs, the admin should make sure no unwanted traffic goes into XSK RQs by either excluding them from RSS or settings up the XDP program to return XDP_PASS for non-XSK traffic. 4. When using a mixed fleet of mlx5e devices and other netdevs, the same configuration can be applied. If the application supports the fallback to copy mode on unsupported drivers, it will work too. ========== Part 4 will include some final xsk optimizations and minor improvements part 1: https://lore.kernel.org/netdev/20220927203611.244301-1-saeed@kernel.org/ part 2: https://lore.kernel.org/netdev/20220929072156.93299-1-saeed@kernel.org/ ==================== Link: https://lore.kernel.org/r/20220930162903.62262-1-saeed@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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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.