d8a210774e
This patch enables the unaligned chunks feature for AF_XDP which allows
chunks to be placed at arbitrary places in the umem, as opposed to them
being required to be aligned to 2k. This allows for DPDK application
mempools to be mapped directly into the umem and in turn enable zero copy
transfer between umem and the PMD.
This patch replaces the zero copy via external mbuf mechanism introduced
in commit e9ff8bb71943 ("net/af_xdp: enable zero copy by external mbuf").
The pmd_zero copy vdev argument is also removed as now the PMD will
auto-detect presence of the unaligned chunks feature and enable it if so
and otherwise fall back to copy mode if not detected.
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Reviewed-by: Xiaolong Ye <xiaolong.ye@intel.com>
60 lines
2.2 KiB
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60 lines
2.2 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2019 Intel Corporation.
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AF_XDP Poll Mode Driver
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==========================
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AF_XDP is an address family that is optimized for high performance
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packet processing. AF_XDP sockets enable the possibility for XDP program to
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redirect packets to a memory buffer in userspace.
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For the full details behind AF_XDP socket, you can refer to
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`AF_XDP documentation in the Kernel
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<https://www.kernel.org/doc/Documentation/networking/af_xdp.rst>`_.
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This Linux-specific PMD driver creates the AF_XDP socket and binds it to a
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specific netdev queue, it allows a DPDK application to send and receive raw
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packets through the socket which would bypass the kernel network stack.
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Current implementation only supports single queue, multi-queues feature will
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be added later.
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Note that MTU of AF_XDP PMD is limited due to XDP lacks support for
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fragmentation.
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AF_XDP PMD enables need_wakeup flag by default if it is supported. This
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need_wakeup feature is used to support executing application and driver on the
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same core efficiently. This feature not only has a large positive performance
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impact for the one core case, but also does not degrade 2 core performance and
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actually improves it for Tx heavy workloads.
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Options
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-------
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The following options can be provided to set up an af_xdp port in DPDK.
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* ``iface`` - name of the Kernel interface to attach to (required);
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* ``start_queue`` - starting netdev queue id (optional, default 0);
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* ``queue_count`` - total netdev queue number (optional, default 1);
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Prerequisites
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-------------
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This is a Linux-specific PMD, thus the following prerequisites apply:
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* A Linux Kernel (version > v4.18) with XDP sockets configuration enabled;
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* libbpf (within kernel version > v5.1-rc4) with latest af_xdp support installed,
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User can install libbpf via `make install_lib` && `make install_headers` in
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<kernel src tree>/tools/lib/bpf;
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* A Kernel bound interface to attach to;
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* For need_wakeup feature, it requires kernel version later than v5.3-rc1;
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* For PMD zero copy, it requires kernel version later than v5.4-rc1;
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Set up an af_xdp interface
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-----------------------------
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The following example will set up an af_xdp interface in DPDK:
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.. code-block:: console
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--vdev net_af_xdp,iface=ens786f1
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