2. 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 compression and decompression

2.1. Features

ISA-L PMD has support for:

Compression/Decompression algorithm:

  • DEFLATE

Huffman code type:

  • FIXED
  • DYNAMIC

Window size support:

  • 32K

2.2. Limitations

  • Chained mbufs are not supported, for future release.
  • Compressdev level 0, no compression, is not supported. ISA-L level 0 used for fixed huffman codes.
  • Checksums are not supported, for future release.

2.3. 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/
    

2.4. 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).