linux-kernel - Re: [PATCH] z3fold: the 3-fold allocator for compressed pages

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Message-ID: <570F5973.40809@suse.cz>
Date:	Thu, 14 Apr 2016 10:48:51 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Vitaly Wool <vitalywool@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc:	Seth Jennings <sjenning@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Streetman <ddstreet@...e.org>
Subject: Re: [PATCH] z3fold: the 3-fold allocator for compressed pages

On 04/14/2016 10:05 AM, Vitaly Wool wrote:
> This patch introduces z3fold, a special purpose allocator for storing
> compressed pages. It is designed to store up to three compressed pages per
> physical page. It is a ZBUD derivative which allows for higher compression
> ratio keeping the simplicity and determinism of its predecessor.

So the obvious question is, why a separate allocator and not extend zbud?
I didn't study the code, nor notice a design/algorithm overview doc, but it 
seems z3fold keeps the idea of one compressed page at the beginning, one at the 
end of page frame, but it adds another one in the middle? Also how is the 
buddy-matching done?

Thanks,
Vlastimil