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

[Nicolas Pitre]

On Tue, 26 Feb 2013, Peter Korsgaard wrote:

> >>>>> "Nicolas" == Nicolas Pitre <nico@xxxxxxxxxxx> writes:
> 
> Hi,
> 
>  >> Did you actually *try* the new LZO version and the patch (which is attached
>  >> once again) as explained in https://lkml.org/lkml/2013/2/3/367 ?
>  >> 
>  >> Because the new LZO version is faster than LZ4 in my testing, at least
>  >> when comparing apples with apples and enabling unaligned access in
>  >> BOTH versions:
>  >> 
>  >> armv7 (Cortex-A9), Linaro gcc-4.6 -O3, Silesia test corpus, 256 kB block-size:
>  >> 
>  >> compression speed   decompression speed
>  >> 
>  >> LZO-2012    :          44 MB/sec          117 MB/sec     no unaligned access
>  >> LZO-2013-UA :          47 MB/sec          167 MB/sec     Unaligned Access
>  >> LZ4 r88  UA :          46 MB/sec          154 MB/sec     Unaligned Access
> 
>  Nicolas> To be fair, you should also take into account the compressed
>  Nicolas> size of a typical ARM kernel.  Sometimes a slightly slower
>  Nicolas> decompressor may be faster overall if the compressed image to
>  Nicolas> work on is smaller.
> 
> Yes, but notice that lzo compressed BETTER than lz4 - E.G. from the
> introduction mail:
> 
> 1. ARMv7, 1.5GHz based board
>    Kernel: linux 3.4
>    Uncompressed Kernel Size: 14MB
>         Compressed Size  Decompression Speed
>    LZO  6.7MB            21.1MB/s
>    LZ4  7.3MB            29.1MB/s, 45.6MB/s(UA)

OK.  If LZO is now faster than LZ4 while still compressing more then I 
have no argument.


Nicolas
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