Messages in this thread | | | Date | Mon, 28 Jan 2013 14:25:10 -0800 | From | Andrew Morton <> | Subject | Re: [RFC PATCH 0/4] Add support for LZ4-compressed kernels |
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On Sat, 26 Jan 2013 14:50:43 +0900 Kyungsik Lee <kyungsik.lee@lge.com> wrote:
> This patchset is for supporting LZ4 compressed kernel and initial ramdisk on > the x86 and ARM architectures. > > According to http://code.google.com/p/lz4/, LZ4 is a very fast lossless > compression algorithm and also features an extremely fast decoder. > > Kernel Decompression APIs are based on implementation by Yann Collet > (http://code.google.com/p/lz4/source/checkout). > De/compression Tools are also provided from the site above. > > The initial test result on ARM(v7) based board shows that the size of kernel > with LZ4 compressed is 8% bigger than LZO compressed but the decompressing > speed is faster(especially under the enabled unaligned memory access). > > Test: 3.4 based kernel built with many modules > Uncompressed kernel size: 13MB > lzo: 6.3MB, 301ms > lz4: 6.8MB, 251ms(167ms, with enabled unaligned memory access) > > It seems that it___s worth trying LZ4 compressed kernel image or ramdisk > for making the kernel boot more faster. > > ... > > 20 files changed, 663 insertions(+), 3 deletions(-) > > ... >
What's this "with enabled unaligned memory access" thing? You mean "if the arch supports CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS"? If so, that's only x86, which isn't really in the target market for this patch, yes?
It's a lot of code for a 50ms boot-time improvement. Does anyone have any opinions on whether or not the benefits are worth the cost?
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