[lkml]   [2013]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC PATCH 0/4] Add support for LZ4-compressed kernels
On 2013-01-30 오전 6:09, Rajesh Pawar wrote:
>> Andrew Morton <> wrote:
>> On Sat, 26 Jan 2013 14:50:43 +0900
>> Kyungsik Lee <> wrote:
>>> This patchset is for supporting LZ4 compressed kernel and initial ramdisk on
>>> the x86 and ARM architectures.
>>> According to [[,]] 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
>>> ([[]]).
>>> 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
>> 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 to know more about it.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2013-02-01 08:21    [W:0.070 / U:0.960 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site