Messages in this thread | | | Date | Thu, 16 May 2013 11:30:34 -0400 | From | Rik van Riel <> | Subject | Re: [PATCHv11 2/4] zbud: add to mm/ |
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On 05/13/2013 08:40 AM, Seth Jennings wrote: > zbud is an special purpose allocator for storing compressed pages. It is > designed to store up to two compressed pages per physical page. While this > design limits storage density, it has simple and deterministic reclaim > properties that make it preferable to a higher density approach when reclaim > will be used. > > zbud works by storing compressed pages, or "zpages", together in pairs in a > single memory page called a "zbud page". The first buddy is "left > justifed" at the beginning of the zbud page, and the last buddy is "right > justified" at the end of the zbud page. The benefit is that if either > buddy is freed, the freed buddy space, coalesced with whatever slack space > that existed between the buddies, results in the largest possible free region > within the zbud page. > > zbud also provides an attractive lower bound on density. The ratio of zpages > to zbud pages can not be less than 1. This ensures that zbud can never "do > harm" by using more pages to store zpages than the uncompressed zpages would > have used on their own. > > This patch adds zbud to mm/ for later use by zswap. > > Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
-- All rights reversed
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