Messages in this thread | | | Date | Fri, 01 Feb 2013 16:00:57 +0900 | From | "kyungsik.lee" <> | Subject | Re: [RFC PATCH 0/4] Add support for LZ4-compressed kernels |
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On 2013-01-30 오전 6:09, Rajesh Pawar wrote: >> Andrew Morton <akpm@linux-foundation.org> wrote: >> >> 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? > BTW, what happened to the proposed LZO update - woudn't it better to merge this first? > > Also, under the hood LZ4 seems to be quite similar to LZO, so probably > LZO speed would also greatly benefit from unaligned access and some other > ARM optimisations > I didn't test with the proposed LZO update you mentioned. Sorry, which one do you mean? I did some tests with the latest LZO in the mainline.
As a result, LZO is not faster in an unaligned access enabled on ARM. Actually Slower.
Decompression time: 336ms(383ms, with unaligned access enabled)
You may refer to https://lkml.org/lkml/2012/10/7/85 to know more about it.
Thanks, Kyungsik
Thanks, Kyungsik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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