Linux kernel source tree
90912f9f4f
Currently, idpf uses the following model for the header buffers: * buffers are allocated via dma_alloc_coherent(); * when receiving, napi_alloc_skb() is called and then the header is copied to the newly allocated linear part. This is far from optimal as DMA coherent zone is slow on many systems and memcpy() neutralizes the idea and benefits of the header split. Not speaking of that XDP can't be run on DMA coherent buffers, but at the same time the idea of allocating an skb to run XDP program is ill. Instead, use libeth to create page_pools for the header buffers, allocate them dynamically and then build an skb via napi_build_skb() around them with no memory copy. With one exception... When you enable header split, you expect you'll always have a separate header buffer, so that you could reserve headroom and tailroom only there and then use full buffers for the data. For example, this is how TCP zerocopy works -- you have to have the payload aligned to PAGE_SIZE. The current hardware running idpf does *not* guarantee that you'll always have headers placed separately. For example, on my setup, even ICMP packets are written as one piece to the data buffers. You can't build a valid skb around a data buffer in this case. To not complicate things and not lose TCP zerocopy etc., when such thing happens, use the empty header buffer and pull either full frame (if it's short) or the Ethernet header there and build an skb around it. GRO layer will pull more from the data buffer later. This W/A will hopefully be removed one day. Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com> |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.