[resending due to mail client issues] On Thu, Apr 14, 2016 at 10:48 AM, Vlastimil Babka <vba...@suse.cz> wrote: > > 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?
Well, as far as I recall Seth was very much for keeping zbud as simple as possible. I am fine either way but if we have zpool API, why not have another zpool API user? > > 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? Basically yes. There is 'start_middle' variable which point to the start of the middle page, if any. The matching is done basing on the buddy number. ~vitaly
