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

Kyungsik Lee
2013-02-27T13:24:05Z

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 have read the comments regarding how many compressors the kernel
should support and understand that it can not support all the
compressors available.

However, I don't think that LZO can be replaced by LZ4 in all the
cases. The benchmark above shows only about improved decompression
speed.

Thanks,
Kyungsik