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

Nicolas Pitre
2013-02-26T22:09:55Z

On Tue, 26 Feb 2013, Peter Korsgaard wrote:

> >>>>> "Nicolas" == Nicolas Pitre <nico@fluxnic.net> 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