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

From: Peter Korsgaard
Date: Tue Feb 26 2013 - 16:58:14 EST

>>>>> "Nicolas" == Nicolas Pitre <nico@xxxxxxxxxxx> writes:


>> Did you actually *try* the new LZO version and the patch (which is attached
>> once again) as explained in ?
>> 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)

Bye, Peter Korsgaard
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