3bc3022918a6a30da1edc668ae55afffc57c6166
[dpdk.git] / isal.rst
1 ..  SPDX-License-Identifier: BSD-3-Clause
2     Copyright(c) 2018 Intel Corporation.
3
4 ISA-L Compression Poll Mode Driver
5 ==================================
6
7 The ISA-L PMD (**librte_pmd_isal_comp**) provides poll mode compression &
8 decompression driver support for utilizing Intel ISA-L library,
9 which implements the deflate algorithm for both Deflate(compression) and Inflate(decompression).
10
11
12 Features
13 --------
14
15 ISA-L PMD has support for:
16
17 Compression/Decompression algorithm:
18
19     * DEFLATE
20
21 Huffman code type:
22
23     * FIXED
24     * DYNAMIC
25
26 Window size support:
27
28     * 32K
29
30 Level guide:
31
32 The ISA-L levels have been mapped to somewhat correspond to the same ZLIB level,
33 i.e. ZLIB L1 gives a compression ratio similar to ISA-L L1.
34 Compressdev level 0 enables "No Compression", which passes the uncompressed
35 data to the output buffer, plus deflate headers.
36 The ISA-L library does not support this, therefore compressdev level 0 is not supported.
37
38 The compressdev API has 10 levels, 0-9. ISA-L has 4 levels of compression, 0-3.
39 As a result the level mappings from the API to the PMD are shown below.
40
41 .. _table_ISA-L_compression_levels:
42
43 .. table:: Level mapping from Compressdev to ISA-L PMD.
44
45    +-------------+----------------------------------------------+-----------------------------------------------+
46    | Compressdev | PMD Functionality                            | Internal ISA-L                                |
47    | API Level   |                                              | Level                                         |
48    +=============+==============================================+===============================================+
49    | 0           | No compression, Not Supported                | ---                                           |
50    +-------------+----------------------------------------------+-----------------------------------------------+
51    | 1           | Dynamic (Fast compression)                   | 1                                             |
52    +-------------+----------------------------------------------+-----------------------------------------------+
53    | 2           | Dynamic                                      | 2                                             |
54    |             | (Higher compression ratio)                   |                                               |
55    +-------------+----------------------------------------------+-----------------------------------------------+
56    | 3           | Dynamic                                      | 3                                             |
57    |             | (Best compression ratio)                     | (Level 2 if                                   |
58    |             |                                              | no AVX512/AVX2)                               |
59    +-------------+----------------------------------------------+-----------------------------------------------+
60    | 4           | Dynamic (Best compression ratio)             | Same as above                                 |
61    +-------------+----------------------------------------------+-----------------------------------------------+
62    | 5           | Dynamic (Best compression ratio)             | Same as above                                 |
63    +-------------+----------------------------------------------+-----------------------------------------------+
64    | 6           | Dynamic (Best compression ratio)             | Same as above                                 |
65    +-------------+----------------------------------------------+-----------------------------------------------+
66    | 7           | Dynamic (Best compression ratio)             | Same as above                                 |
67    +-------------+----------------------------------------------+-----------------------------------------------+
68    | 8           | Dynamic (Best compression ratio)             | Same as above                                 |
69    +-------------+----------------------------------------------+-----------------------------------------------+
70    | 9           | Dynamic (Best compression ratio)             | Same as above                                 |
71    +-------------+----------------------------------------------+-----------------------------------------------+
72
73 .. Note::
74
75  The above table only shows mapping when API calls for dynamic compression.
76  For fixed compression, regardless of API level, internally ISA-L level 0 is always used.
77
78 Limitations
79 -----------
80
81 * Compressdev level 0, no compression, is not supported.
82
83 * Checksums will not be supported until future release.
84
85 Installation
86 ------------
87
88 * To build DPDK with Intel's ISA-L library, the user is required to download the library from `<https://github.com/01org/isa-l>`_.
89
90 * Once downloaded, the user needs to build the library, the ISA-L autotools are usually sufficient::
91
92     ./autogen.sh
93     ./configure
94
95 * make can  be used to install the library on their system, before building DPDK::
96
97     make
98     sudo make install
99
100 * To build with meson, the **libisal.pc** file, must be copied into "pkgconfig",
101   e.g. /usr/lib/pkgconfig or /usr/lib64/pkgconfig depending on your system,
102   for meson to find the ISA-L library. The **libisal.pc** is located in library sources::
103
104     cp isal/libisal.pc /usr/lib/pkgconfig/
105
106
107 Initialization
108 --------------
109
110 In order to enable this virtual compression PMD, user must:
111
112 * Set ``CONFIG_RTE_LIBRTE_PMD_ISAL=y`` in config/common_base.
113
114 To use the PMD in an application, user must:
115
116 * Call ``rte_vdev_init("compress_isal")`` within the application.
117
118 * Use ``--vdev="compress_isal"`` in the EAL options, which will call ``rte_vdev_init()`` internally.
119
120 The following parameter (optional) can be provided in the previous two calls:
121
122 * ``socket_id:`` Specify the socket where the memory for the device is going to be allocated
123   (by default, socket_id will be the socket where the core that is creating the PMD is running on).