linux-kernel - Re: [RFC] LZO de/compression support

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Date:	Mon, 28 May 2007 10:49:48 -0400
From:	Daniel Hazelton <dhazelton@...er.net>
To:	"Nitin Gupta" <nitingupta910@...il.com>
Cc:	lkml <linux-kernel@...r.kernel.org>, linux-mm-cc@...top.org,
	linuxcompressed-devel@...ts.sourceforge.net,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Richard Purdie" <richard@...nedhand.com>,
	"Bret Towe" <magnade@...il.com>,
	"Satyam Sharma" <satyam.sharma@...il.com>
Subject: Re: [RFC] LZO de/compression support - take 6

On Monday 28 May 2007 10:40:31 Nitin Gupta wrote:
> Hi,
>
> Attached is tester code used for testing.
> (developed by Daniel Hazelton -- modified slightly to now use 'take 6'
> version for 'TinyLZO')
>
> Cheers,
> Nitin
>

<snip>
I haven't tested with version 6, but after removing the LZO_CHECK_MPOS_NON_DET 
macro from the 'take 5' code and replacing the open-coded byte-for-byte 
copies with calls to memcpy:

10000 run averages:
'Tiny LZO':
        Combined: 57.4691 usec
        Compression: 39.8837 usec
        Decompression: 17.5854 usec
'miniLZO':
        Combined: 64.0484 usec
        Compression: 46.0604 usec
        Decompression: 17.988 usec

which means:
Overall TinyLZO is 10.2% faster
TinyLZO compresses 13.4% faster
TinyLZO decompresses 2.23% faster

-Benchmark run a a Pentium-M 1.73GHz, 1GB Ram
With the speed-up seen with just the removal of the LZO_CHECK_MPOS_NON_DET I 
wasn't sure that changing the open-coded copy to a call to memcpy() was going 
to have a big impact on the code, but it does appear to have has several 
percentage points of difference. (Though I am unsure about the speed increase 
with the decompression - I didn't touch that file when making this set of 
changes. I'm going to make the memcpy() changes to 'take 6' and see if the 
speed-up holds true)

DRH
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