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

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Message-id: <alpine.LFD.2.03.1302261708120.1254@syhkavp.arg>
Date:	Tue, 26 Feb 2013 17:09:51 -0500 (EST)
From:	Nicolas Pitre <nico@...xnic.net>
To:	Peter Korsgaard <jacmet@...site.dk>
Cc:	"Markus F.X.J. Oberhumer" <markus@...rhumer.com>,
	Kyungsik Lee <kyungsik.lee@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Russell King <linux@....linux.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-kbuild@...r.kernel.org, x86@...nel.org,
	celinux-dev@...ts.celinuxforum.org,
	Nitin Gupta <nitingupta910@...il.com>,
	Richard Purdie <rpurdie@...nedhand.com>,
	Josh Triplett <josh@...htriplett.org>,
	Joe Millenbach <jmillenbach@...il.com>,
	David Sterba <dsterba@...e.cz>,
	Richard Cochran <richardcochran@...il.com>,
	Albin Tonnerre <albin.tonnerre@...e-electrons.com>,
	Egon Alter <egon.alter@....net>, hyojun.im@....com,
	chan.jeong@....com, raphael.andy.lee@...il.com
Subject: Re: [RFC PATCH v2 0/4] Add support for LZ4-compressed kernel

On Tue, 26 Feb 2013, Peter Korsgaard wrote:

> >>>>> "Nicolas" == Nicolas Pitre <nico@...xnic.net> writes:
> 
> Hi,
> 
>  >> 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
> 
>  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)

OK.  If LZO is now faster than LZ4 while still compressing more then I 
have no argument.


Nicolas
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