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.. 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).
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