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


Markus F.X.J. Oberhumer <markus@...>
 

On 2013-02-26 07:24, Kyungsik Lee wrote:
Hi,

[...]

Through the benchmark, it was found that -Os Compiler flag for
decompress.o brought better decompression performance in most of cases
(ex, different compiler and hardware spec.) in ARM architecture.

Lastly, CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is not always the best
option even though it is supported. The decompression speed can be
slightly slower in some cases.

This patchset is based on 3.8.

Any comments are appreciated.
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

~Markus



Thanks,
Kyungsik


Benchmark Results(PATCH v2)
Compiler: Linaro ARM gcc 4.6.2
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)
2. ARMv7, 1.7GHz based board
Kernel: linux 3.7
Uncompressed Kernel Size: 14MB
Compressed Size Decompression Speed
LZO 6.0MB 34.1MB/s
LZ4 6.5MB 86.7MB/s
UA: Unaligned memory Access support


Change log: v2
- Clean up code
- Enable unaligned access for ARM v6 and above with
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
- Add lz4_decompress() for faster decompression with
uncompressed output size
- Use lz4_decompress() for LZ4-compressed kernel during
boot-process
- Apply -Os to decompress.o to improve decompress
performance during boot-up process


Kyungsik Lee (4):
decompressor: Add LZ4 decompressor module
lib: Add support for LZ4-compressed kernel
arm: Add support for LZ4-compressed kernel
x86: Add support for LZ4-compressed kernel

arch/arm/Kconfig | 1 +
arch/arm/boot/compressed/.gitignore | 1 +
arch/arm/boot/compressed/Makefile | 6 +-
arch/arm/boot/compressed/decompress.c | 4 +
arch/arm/boot/compressed/piggy.lz4.S | 6 +
arch/x86/Kconfig | 1 +
arch/x86/boot/compressed/Makefile | 5 +-
arch/x86/boot/compressed/misc.c | 4 +
include/linux/decompress/unlz4.h | 10 +
include/linux/lz4.h | 48 +++++
init/Kconfig | 13 +-
lib/Kconfig | 7 +
lib/Makefile | 2 +
lib/decompress.c | 5 +
lib/decompress_unlz4.c | 190 +++++++++++++++++++
lib/lz4/Makefile | 1 +
lib/lz4/lz4_decompress.c | 331 ++++++++++++++++++++++++++++++++++
lib/lz4/lz4defs.h | 93 ++++++++++
scripts/Makefile.lib | 5 +
usr/Kconfig | 9 +
20 files changed, 739 insertions(+), 3 deletions(-)
create mode 100644 arch/arm/boot/compressed/piggy.lz4.S
create mode 100644 include/linux/decompress/unlz4.h
create mode 100644 include/linux/lz4.h
create mode 100644 lib/decompress_unlz4.c
create mode 100644 lib/lz4/Makefile
create mode 100644 lib/lz4/lz4_decompress.c
create mode 100644 lib/lz4/lz4defs.h

--
Markus Oberhumer, <markus@...>, http://www.oberhumer.com/

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