Re: [GIT PULL] Update LZO compression

From: Roman Mamedov <rm@romanrm.ru>
To: Johannes Stezenbach <js@sig21.net>
Cc: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>,
	linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
	chris.mason@fusionio.com, linux-btrfs@vger.kernel.org,
	Nitin Gupta <ngupta@vflare.org>,
	Richard Purdie <rpurdie@openedhand.com>,
	richard -rw- weinberger <richard.weinberger@gmail.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [GIT PULL] Update LZO compression
Date: Thu, 16 Aug 2012 23:25:49 +0600	[thread overview]
Message-ID: <20120816232549.4d14a6aa@natsu> (raw)
In-Reply-To: <20120816150647.GA22010@sig21.net>

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On Thu, 16 Aug 2012 17:06:47 +0200
Johannes Stezenbach <js@sig21.net> wrote:

> Well, ~2x speedup on x86 is certainly a good achievement, but there
> are more ARM based devices than there are PCs, and I guess many
> embedded devices use lzo compressed kernels and file systems
> while I'm not convinced many PCs rely on lzo in the kernel.

Keep in mind that a major user of LZO is the BTRFS filesystem, and I believe it
is used much more often on larger machines than on ARM, in fact it had problems
operating on ARM at all, until quite recently.

> I know everyone's either busy or on vacation, but it would
> be so cool if someone could test on a more modern ARM core,
> with the userspace test code I posted it should be easy to do.

I have locked the Allwinner A10 CPU in my Mele A2000 to 60 MHz using cpufreq-set,
and ran your test. rnd.lzo is a 9 MB file from /dev/urandom compressed with lzo.
There doesn't seem to be a significant difference between all three variants.

# time for i in {1..20}; do old/unlzop < rnd.lzo >/dev/null ; done

real	0m11.353s
user	0m3.060s
sys	0m8.170s
# time for i in {1..20}; do new/unlzop < rnd.lzo >/dev/null ; done

real	0m11.416s
user	0m3.030s
sys	0m8.200s
# time for i in {1..20}; do test/unlzop < rnd.lzo >/dev/null ; done

real	0m11.310s
user	0m3.100s
sys	0m8.150s

-- 
With respect,
Roman

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Stallman had a printer,
with code he could not see.
So he began to tinker,
and set the software free."

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