From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Joe Perches <joe@perches.com>
Cc: Nicolas Pitre <nico@fluxnic.net>,
Peter Korsgaard <jacmet@sunsite.dk>,
"Markus F.X.J. Oberhumer" <markus@oberhumer.com>,
Kyungsik Lee <kyungsik.lee@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Michal Marek <mmarek@suse.cz>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
x86@kernel.org, celinux-dev@lists.celinuxforum.org,
Nitin Gupta <nitingupta910@gmail.com>,
Richard Purdie <rpurdie@openedhand.com>,
Josh Triplett <josh@joshtriplett.org>,
Joe Millenbach <jmillenbach@gmail.com>,
David Sterba <dsterba@suse.cz>,
Richard Cochran <richardcochran@gmail.com>,
Albin Tonnerre <albin.tonnerre@free-electrons.com>,
Egon Alter <egon.alter@gmx.net>,
hyojun.im@lge.com, chan.jeong@lge.com,
raphael.andy.lee@gmail.com
Subject: Re: [RFC PATCH v2 0/4] Add support for LZ4-compressed kernel
Date: Wed, 27 Feb 2013 17:57:50 +0000 [thread overview]
Message-ID: <20130227175750.GD17833@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1361986787.20540.8.camel@joe-AO722>
On Wed, Feb 27, 2013 at 09:39:47AM -0800, Joe Perches wrote:
> On Wed, 2013-02-27 at 12:16 -0500, Nicolas Pitre wrote:
> > On Wed, 27 Feb 2013, Joe Perches wrote:
> > > On Wed, 2013-02-27 at 16:31 +0000, Russell King - ARM Linux wrote:
> > > > On Wed, Feb 27, 2013 at 07:49:12AM -0800, Joe Perches wrote:
> > > > > On Wed, 2013-02-27 at 09:56 +0000, Russell King - ARM Linux wrote:
> > > > > > On Tue, Feb 26, 2013 at 05:40:34PM -0800, Joe Perches wrote:
> > > > > > > On Tue, 2013-02-26 at 22:10 +0000, Russell King - ARM Linux wrote:
> > > > > > > > So... for a selected kernel version of a particular size, can we please
> > > > > > > > have a comparison between the new LZO code and this LZ4 code, so that
> > > > > > > > we can see whether it's worth updating the LZO code or replacing the
> > > > > > > > LZO code with LZ4?
> > > > > > >
> > > > > > > How could it be questionable that it's worth updating the LZO code?
> > > > > >
> > > > > > Please read the comments against the previous posting of these patches
> > > > > > where I first stated this argument - and with agreement from those
> > > > > > following the thread. The thread started on 26 Jan 2013. Thanks.
> > > > >
> > > > > https://lkml.org/lkml/2013/1/29/145
> > > > >
> > > > > I did not and do not see significant value in
> > > > > adding LZ4 given Markus' LZO improvements.
> > > >
> > > > Sorry, a 66% increase in decompression speed over the updated LZO code
> > > > isn't "significant value" ?
> > >
> > > We disagree.
> > >
> > > > I'm curious - what in your mind qualifies "significant value" ?
> > >
> > > faster boot time. smaller, faster overall code.
> >
> > Sorry, but you certainly successfully got me confused, and probably
> > others as well.
> >
> > RMK says that "66% increase in decompression speed over LZO" is
> > significant. You apparently disagree with that.
>
> Yeah, I can see how that can be interpreted.
> I'm referring only to the new LZO.
>
> I guess Russell has not reviewed the new LZO.
>
> There is apparently no speed increase for LZ4 over
> the new LZO.
Total claptrap. I've no idea where you're getting your data from, but
it's franky wrong and you're now being totally misleading to anyone
else reading this thread.
I explicitly asked for a comparison of the _new_ LZO vs the LZ4 code,
and this is what I received from Kyungsik Lee in this thread:
Compiler: Linaro ARM gcc 4.6.2
2. ARMv7, 1.7GHz based board
Kernel: linux 3.7
Uncompressed Kernel Size: 14MB
Compressed Size Decompression Speed
LZO 6.0MB 34.1MB/s Old
----------------------------------------
6.0MB 34.7MB/s New
6.0MB 52.2MB/s(UA)
=============================================
LZ4 6.5MB 86.7MB/s
UA: Unaligned memory Access support
And my statement of a "66% increase in speed" of LZ4 is comparing the
_new_ LZO code with unaligned access with the LZ4 code.
Now, you refer to Markus' results - but Markus' results do not say what
they're comparing - they don't say what the size of the compressed image
is, nor what the size of the uncompressed image was.
Now, Markus' results show a 42% increase in speed between the LZO-2012
and LZO-2013-UA versions (do the calculation yourself - I'm sure you're
capable of that? If not, we can turn this into a maths lesson too).
The above shows a 53% increase in speed between the existing LZO code
and the new LZO code with unaligned accesses.
_But_ the above shows an additional 66% increase between the new LZO
code with unaligned accesses and LZ4. Or, a whopping 150% increase
in speed over the _existing_ LZO code.
So please, stop stating what I have and have not reviewed. Unlike you,
I _have_ been following everything that's been said in this thread, and
- unlike you - I have analysed the figures put forward and drawn
conclusions which are fully supported by the published data from them,
and stated them - now many times.
next prev parent reply other threads:[~2013-02-27 17:59 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-26 6:24 [RFC PATCH v2 0/4] Add support for LZ4-compressed kernel Kyungsik Lee
2013-02-26 6:24 ` [RFC PATCH v2 1/4] decompressor: Add LZ4 decompressor module Kyungsik Lee
2013-02-26 13:12 ` David Sterba
2013-02-27 4:38 ` Kyungsik Lee
2013-02-26 6:24 ` [RFC PATCH v2 2/4] lib: Add support for LZ4-compressed kernel Kyungsik Lee
2013-02-26 14:00 ` David Sterba
2013-02-28 5:22 ` Kyungsik Lee
2013-02-26 6:24 ` [RFC PATCH v2 3/4] arm: " Kyungsik Lee
2013-02-26 6:24 ` [RFC PATCH v2 4/4] x86: " Kyungsik Lee
2013-02-26 20:33 ` [RFC PATCH v2 0/4] " Markus F.X.J. Oberhumer
2013-02-26 20:59 ` Nicolas Pitre
2013-02-26 21:58 ` Peter Korsgaard
2013-02-26 22:09 ` Nicolas Pitre
2013-02-26 22:10 ` Russell King - ARM Linux
2013-02-27 1:40 ` Joe Perches
2013-02-27 9:56 ` Russell King - ARM Linux
2013-02-27 15:49 ` Joe Perches
2013-02-27 16:08 ` Nicolas Pitre
2013-02-27 16:31 ` Russell King - ARM Linux
2013-02-27 16:53 ` Borislav Petkov
2013-02-27 17:04 ` Joe Perches
2013-02-27 17:16 ` Nicolas Pitre
2013-02-27 17:39 ` Joe Perches
2013-02-27 17:52 ` Nicolas Pitre
2013-02-27 17:57 ` Russell King - ARM Linux [this message]
2013-02-27 17:36 ` Russell King - ARM Linux
2013-02-28 4:22 ` Joe Perches
2013-02-27 7:36 ` Kyungsik Lee
2013-02-27 9:51 ` Russell King - ARM Linux
2013-02-27 10:20 ` Johannes Stezenbach
2013-02-27 15:35 ` Nicolas Pitre
2013-02-27 13:23 ` Kyungsik Lee
2013-02-27 22:21 ` Andrew Morton
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