45bba02c95
This patch enables need_wakeup flag for Tx and fill rings, when this flag is set by the driver, it means that the userspace application has to explicitly wake up the kernel Rx or kernel Tx processing by issuing a syscall. Poll() can wake up both and sendto() or its alternatives will wake up Tx processing only. This feature is to provide efficient support for case that application and driver executing on the same core. Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com> Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
60 lines
2.3 KiB
ReStructuredText
60 lines
2.3 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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* ``pmd_zero_copy`` - enable zero copy or not (optional, default 0);
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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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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,queue=0
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