Re: [RFC PATCH v2 0/4] Add support for LZ4-compressed kernel


Johannes Stezenbach <js@...>
 

On Wed, Feb 27, 2013 at 09:51:39AM +0000, Russell King - ARM Linux wrote:
On Wed, Feb 27, 2013 at 04:36:47PM +0900, Kyungsik Lee wrote:
Compiler: Linaro ARM gcc 4.6.2
2. ARMv7, 1.7GHz based board
Kernel: linux 3.7
Uncompressed Kernel Size: 14MB
Compressed Size Decompression Speed
LZO 6.0MB 34.1MB/s Old
----------------------------------------
6.0MB 34.7MB/s New
6.0MB 52.2MB/s(UA)
=============================================
LZ4 6.5MB 86.7MB/s
UA: Unaligned memory Access support
That is pretty conclusive - it shows an 8% increase in image size vs a
66% increase in decompression speed. It will take a _lot_ to offset
that increase in decompression speed.

So, what I think is that yes, we should accept LZ4 and drop LZO from
the kernel - the "fast but may not be small" compression title has
clearly been taken by LZ4.
I think LZO may be used by squashfs, jffs2 and btrfs, thus you
cannot drop it without breaking on disk storage formats.

Johannes

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