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As part of driver init, all Rx queues are filled with buffers for hardware usage. Later, when a packet is received, a new buffer should be allocated to be used by hardware instead of the received buffer. Packet's processing time includes allocation time, which can be improved using page pool. Using page pool, DMA mapping is done only for first allocation of buffers. As subsequent buffers allocation avoid DMA mapping, it results in performance improvement. The purpose of page pool is to allocate pages fast from cache without locking. This lockless guarantee naturally comes from running under a NAPI. Use page pool to allocate the data buffer only, so hardware will use it to fill the packet. At completion time, attach the data buffer (now filled with packet payload) to new SKB which is allocated around the received buffer. SKB building at completion time prevents cache miss for each packet, as now the SKB is allocated right before packets will be handled by networking stack. Page pool for each Rx queue enhances Rx side performance by reclaiming buffers back to each queue specific pool. This change significantly improves driver performance, CPU can handle about 345% of the packets per second it previously handled. Signed-off-by: Amit Cohen <amcohen@nvidia.com> Reviewed-by: Petr Machata <petrm@nvidia.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: Petr Machata <petrm@nvidia.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com> Link: https://lore.kernel.org/r/1cf788a8f43c70aae6d526018ef77becb27ad6d3.1718709196.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.