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diff --git a/doc/guides/compressdevs/isal.rst b/doc/guides/compressdevs/isal.rst new file mode 100644 index 00000000..3bc30229 --- /dev/null +++ b/doc/guides/compressdevs/isal.rst @@ -0,0 +1,123 @@ +.. SPDX-License-Identifier: BSD-3-Clause + Copyright(c) 2018 Intel Corporation. + +ISA-L Compression Poll Mode Driver +================================== + +The ISA-L PMD (**librte_pmd_isal_comp**) provides poll mode compression & +decompression driver support for utilizing Intel ISA-L library, +which implements the deflate algorithm for both Deflate(compression) and Inflate(decompression). + + +Features +-------- + +ISA-L PMD has support for: + +Compression/Decompression algorithm: + + * DEFLATE + +Huffman code type: + + * FIXED + * DYNAMIC + +Window size support: + + * 32K + +Level guide: + +The ISA-L levels have been mapped to somewhat correspond to the same ZLIB level, +i.e. ZLIB L1 gives a compression ratio similar to ISA-L L1. +Compressdev level 0 enables "No Compression", which passes the uncompressed +data to the output buffer, plus deflate headers. +The ISA-L library does not support this, therefore compressdev level 0 is not supported. + +The compressdev API has 10 levels, 0-9. ISA-L has 4 levels of compression, 0-3. +As a result the level mappings from the API to the PMD are shown below. + +.. _table_ISA-L_compression_levels: + +.. table:: Level mapping from Compressdev to ISA-L PMD. + + +-------------+----------------------------------------------+-----------------------------------------------+ + | Compressdev | PMD Functionality | Internal ISA-L | + | API Level | | Level | + +=============+==============================================+===============================================+ + | 0 | No compression, Not Supported | --- | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 1 | Dynamic (Fast compression) | 1 | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 2 | Dynamic | 2 | + | | (Higher compression ratio) | | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 3 | Dynamic | 3 | + | | (Best compression ratio) | (Level 2 if | + | | | no AVX512/AVX2) | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 4 | Dynamic (Best compression ratio) | Same as above | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 5 | Dynamic (Best compression ratio) | Same as above | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 6 | Dynamic (Best compression ratio) | Same as above | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 7 | Dynamic (Best compression ratio) | Same as above | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 8 | Dynamic (Best compression ratio) | Same as above | + +-------------+----------------------------------------------+-----------------------------------------------+ + | 9 | Dynamic (Best compression ratio) | Same as above | + +-------------+----------------------------------------------+-----------------------------------------------+ + +.. Note:: + + The above table only shows mapping when API calls for dynamic compression. + For fixed compression, regardless of API level, internally ISA-L level 0 is always used. + +Limitations +----------- + +* Compressdev level 0, no compression, is not supported. + +* Checksums will not be supported until future release. + +Installation +------------ + +* To build DPDK with Intel's ISA-L library, the user is required to download the library from `<https://github.com/01org/isa-l>`_. + +* Once downloaded, the user needs to build the library, the ISA-L autotools are usually sufficient:: + + ./autogen.sh + ./configure + +* make can be used to install the library on their system, before building DPDK:: + + make + sudo make install + +* To build with meson, the **libisal.pc** file, must be copied into "pkgconfig", + e.g. /usr/lib/pkgconfig or /usr/lib64/pkgconfig depending on your system, + for meson to find the ISA-L library. The **libisal.pc** is located in library sources:: + + cp isal/libisal.pc /usr/lib/pkgconfig/ + + +Initialization +-------------- + +In order to enable this virtual compression PMD, user must: + +* Set ``CONFIG_RTE_LIBRTE_PMD_ISAL=y`` in config/common_base. + +To use the PMD in an application, user must: + +* Call ``rte_vdev_init("compress_isal")`` within the application. + +* Use ``--vdev="compress_isal"`` in the EAL options, which will call ``rte_vdev_init()`` internally. + +The following parameter (optional) can be provided in the previous two calls: + +* ``socket_id:`` Specify the socket where the memory for the device is going to be allocated + (by default, socket_id will be the socket where the core that is creating the PMD is running on). |