1/13/2024 0 Comments Netmap vs dpdkThe structures' fields are Netmap related and are self- explanatory for developers familiar with Netmap. ``struct rte_netmap_conf`` and ``struct rte_netmap_port_conf``. These two initialization functions take ``compat_netmap`` specific data structures as parameters: Namely ``rte_netmap_init() `` and ``rte_netmap_init_port() ``. The ported application needs to call initialization functions for the ``compat_netmap`` library, In addition of the regular DPDK initialization code, Please refer to the * DPDK Programmer's Guide* and example source code for details about initialization. The usual DPDK initialization code involving ``rte_eal_init() `` and ``rte_pci_probe() `` has to be added to the Netmap application in the same way it is used in all other DPDK sample applications. Since the ``compat_netmap`` functions have the same signature as the usual libc calls, the change is trivial in most cases. * Adding further DPDK initialization code. * Changing the system calls to use their ``compat_netmap`` library counterparts. Porting Netmap applications typically involves two major steps: This interface is not available when using this compatibility layer. * The Netmap kernel module exposes a sysfs interface to change some internal parameters, such as the size of the shared memory region. This is not the case with this compatibility layer. * The Netmap manual page states that "*a device obtained through /dev/netmap also supports the ioctl supported by network devices*". Slot flags and so on are not supported or are simply not relevant in the DPDK model. * Not all of Netmap's features are supported: host rings, It effectively turns calls to the ``poll() `` system call made in a Netmap application into polling of the DPDK ports,Ĭhanging the semantics of the usual POSIX defined poll. * The ``rte_netmap_poll() `` function only supports infinite ( negative) or zero time outs. The address, length, flags, offset, and other arguments are ignored. * The ``rte_netmap_mmap() `` function merely returns the address of a DPDK memzone. * Any system call that can potentially affect file descriptors cannot be used with a descriptor returned by the ``rte_netmap_open() `` function. These may change as the library is updated: There are caveats and limitations to be aware of when trying to use the ``compat_netmap`` library, the most important of these are listed below. Given the difference between the way Netmap and the DPDK approach packet I/O, * ``rte_netmap_poll() `` They use the same signature as their libc counterparts, and can be used as drop- in replacements in most cases. The library provides the following drop- in replacements for system calls usually used in Netmap applications: Please refer to the Netmap distribution for details about Netmap. Knowledge of Netmap is required to understand the rest of this section. The provided library is currently minimal and doesn't support all the features that Netmap supports,īut is enough to run simple applications, such as the bridge example detailed below. The ``compat_netmap`` library provides a set of similar APIs to use in place of those system calls,Įffectively turning a Netmap application into a DPDK application. Since Netmap applications use regular system calls, like ``open() ``, ``ioctl() `` and ``mmap() `` to communicate with the Netmap kernel module performing the packet I/O, The Netmap compatibility library provides a minimal set of APIs to give programs written against the Netmap APIs the ability to be run, with minimal changes to their source code, using the DPDK to perform the actual packet I/O. SPDX- License- Identifier: BSD-3- Clause Copyright(c) 2010-2014 Intel Corporation.
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