.. SPDX-License-Identifier: BSD-3-Clause Copyright(c) 2018 Intel Corporation. ISA-L Compression Poll Mode Driver ================================== The ISA-L PMD (**librte_compress_isal**) 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 Checksum: * CRC32 * ADLER32 To enable a checksum in the driver, the compression and/or decompression xform structure, rte_comp_xform, must be filled with either of the CompressDev checksum flags supported. :: compress_xform->compress.chksum = RTE_COMP_CHECKSUM_CRC32 decompress_xform->decompress.chksum = RTE_COMP_CHECKSUM_CRC32 :: compress_xform->compress.chksum = RTE_COMP_CHECKSUM_ADLER32 decompress_xform->decompress.chksum = RTE_COMP_CHECKSUM_ADLER32 If you request a checksum for compression or decompression, the checksum field in the operation structure, ``op->output_chksum``, will be filled with the checksum. .. Note:: For the compression case above, your output buffer will need to be large enough to hold the compressed data plus a scratchpad for the checksum at the end, the scratchpad is 8 bytes for CRC32 and 4 bytes for Adler32. 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. Installation ------------ * To build DPDK with Intel's ISA-L library, the user is required to download the library from ``_. * 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 -------------- 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).