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Thread: Support For Compressing The Linux Kernel With LZ4

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  1. #1
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    Default Support For Compressing The Linux Kernel With LZ4

    Phoronix: Support For Compressing The Linux Kernel With LZ4

    A set of patches that allow the Linux kernel image to be compressed with the LZ4 lossless compression algorithm have been published. The size of LZ4-compressed Linux kernel images are larger than using LZO compression, but there's promise that the boot times could be better...

    http://www.phoronix.com/vr.php?view=MTI4NjM

  2. #2
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    Quote Originally Posted by BO$$ View Post
    What is the point of having a compressed kernel? Faster loading times from the HDD?
    Smaller footprint which means: yes faster loading times from hdd, smaller filesize ON the hdd (embedded) and means it can be shoved into RAM if you wanted the entire live system into ram for responsiveness

  3. #3
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    what happened to btrfs's lz4 compression support?

    it seems lz4 makes sense a lot for always compressing files when not using a sandforce ssd.

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    I wonder what would happen if a lossy algorythem was used

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    Quote Originally Posted by AJenbo View Post
    I wonder what would happen if a lossy algorythem was used
    then you have a lossy system.

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    Quote Originally Posted by AJenbo View Post
    I wonder what would happen if a lossy algorythem was used
    Then i'd hope that the decompression algorithm was very good about reconstructing the lost data which would probably mean a longer decompression time =P

  7. #7
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    come on... 100ms difference, you cannot even measure that with your watch. But you can measure the init-time after the kernel is loaded...

  8. #8

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    Quote Originally Posted by mercutio View Post
    what happened to btrfs's lz4 compression support?

    it seems lz4 makes sense a lot for always compressing files when not using a sandforce ssd.
    Perhaps you are thinking of ZFS. ZFSOnLinux HEAD has LZ4 support. I believe that btrfs had planned to adopt snappy. The two compression algorithms are roughly equivalent in benchmarks.

  9. #9
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    Quote Originally Posted by ryao View Post
    Perhaps you are thinking of ZFS. ZFSOnLinux HEAD has LZ4 support. I believe that btrfs had planned to adopt snappy. The two compression algorithms are roughly equivalent in benchmarks.
    http://www.phoronix.com/scan.php?pag...tem&px=MTA1OTQ

    looks like lz4 is about 25 to 30% faster than snappy.
    Last edited by mercutio; 02-01-2013 at 05:50 PM.

  10. #10

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    Quote Originally Posted by mercutio View Post
    http://www.phoronix.com/scan.php?pag...tem&px=MTA1OTQ

    looks like lz4 is about 25 to 30% faster than snappy.
    I had recalled reading the following when saying that the two were roughly equivalent:

    http://extrememoderate.wordpress.com...ession-part-1/

    The LZ4 website has benchmarks that are probably more accurate:

    http://code.google.com/p/lz4/

    According to them, LZ4 is faster than Snappy. The compression rate is 45% higher while the decompression rate is 26% higher. The compression ratio of LZ4 is also slightly higher than that of snappy.

    With that said, it appears that btrfs support for both Snappy and LZ4 has not been merged:

    https://btrfs.wiki.kernel.org/index....merged_Patches

    Gentoo Linux's ZFS kernel modules gained support for LZ4 two days ago. Gentoo's GRUB package was updated with support for booting off LZ4 compressed ZFS /boot datasets yesterday. People interested in filesystems that support LZ4 compression could always try ZFS.

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