linux-kernel - Re: [GIT PULL] Update LZO compression

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Date:	Thu, 16 Aug 2012 12:48:49 -0400
From:	Jeff Garzik <jgarzik@...ox.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	"Markus F.X.J. Oberhumer" <markus@...rhumer.com>,
	Johannes Stezenbach <js@...21.net>,
	linux-kernel@...r.kernel.org, chris.mason@...ionio.com,
	linux-btrfs@...r.kernel.org, Nitin Gupta <ngupta@...are.org>,
	Richard Purdie <rpurdie@...nedhand.com>,
	richard -rw- weinberger <richard.weinberger@...il.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [GIT PULL] Update LZO compression

On 08/16/2012 12:20 PM, Andi Kleen wrote:
>> If you think a little bit, I bet you could come up with a solution that
>> operates at cacheline-aligned granularity, something that would be _even
>> faster_ than simply fixing the code to do aligned accesses.
>
> Cache aligned compression is unlikely to compress anything at all.
> Compression algorithms are usually by definition unaligned.

Sure it's a bitstream, but that does not imply the impossibility of 
reading data in in an word-aligned manner.

Maybe cache-aligned is ambitious, because of resultant code bloat, but 
machine-int-aligned is doable and reasonable.

	Jeff




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