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| ** ZCACHE PLAN FOR PROMOTION FROM STAGING ** |
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| Last updated: Feb 13, 2013 |
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| PLAN STEPS |
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| 1. merge zcache and ramster to eliminate horrible code duplication |
| 2. converge on a predictable, writeback-capable allocator |
| 3. use debugfs instead of sysfs (per akpm feedback in 2011) |
| 4. zcache side of cleancache/mm WasActive patch |
| 5. zcache side of frontswap exclusive gets |
| 6. zcache must be able to writeback to physical swap disk |
| (per Andrea Arcangeli feedback in 2011) |
| 7. implement adequate policy for writeback |
| 8. frontswap/cleancache work to allow zcache to be loaded |
| as a module |
| 9. get core mm developer to review |
| 10. incorporate feedback from review |
| 11. get review/acks from 1-2 additional mm developers |
| 12. incorporate any feedback from additional mm reviews |
| 13. propose location/file-naming in mm tree |
| 14. repeat 9-13 as necessary until akpm is happy and merges |
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| STATUS/OWNERSHIP |
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| 1. DONE as part of "new" zcache; in staging/zcache for 3.9 |
| 2. DONE as part of "new" zcache (cf zbud.[ch]); in staging/zcache for 3.9 |
| (this was the core of the zcache1 vs zcache2 flail) |
| 3. DONE as part of "new" zcache; in staging/zcache for 3.9 |
| 4. DONE (w/caveats) as part of "new" zcache; per cleancache performance |
| feedback see https://lkml.org/lkml/2011/8/17/351, in |
| staging/zcache for 3.9; dependent on proposed mm patch, see |
| https://lkml.org/lkml/2012/1/25/300 |
| 5. DONE as part of "new" zcache; performance tuning only, |
| in staging/zcache for 3.9; dependent on frontswap patch |
| merged in 3.7 (33c2a174) |
| 6. DONE (w/caveats), prototyped as part of "new" zcache, had |
| bad memory leak; reimplemented to use sjennings clever tricks |
| and proposed mm patches with new version in staging/zcache |
| for 3.9, see https://lkml.org/lkml/2013/2/6/437; |
| 7. PROTOTYPED as part of "new" zcache; in staging/zcache for 3.9; |
| needs more review (plan to discuss at LSF/MM 2013) |
| 9. IN PROGRESS; owned by Konrad Wilk; Mel Gorman provided |
| great feedback in August 2012 (unfortunately of "old" |
| zcache) |
| 11. NOT DONE; owned by Konrad Wilk and Bob Liu |
| 12. TBD (depends on quantity of feedback) |
| 13. PROPOSED; one suggestion proposed by Dan; needs more ideas/feedback |
| 14. TBD (depends on feedback) |
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| WHO NEEDS TO AGREE |
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| Not sure. Seth Jennings is now pursuing a separate but semi-parallel |
| track. Akpm clearly has to approve for any mm merge to happen. Minchan |
| Kim has interest but may be happy if/when zram is merged into mm. Konrad |
| Wilk may be maintainer if akpm decides compression is maintainable |
| separately from the rest of mm. (More LSF/MM 2013 discussion.) |
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| ZCACHE FUTURE NEW FUNCTIONALITY |
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| A. Support zsmalloc as an alternative high-density allocator |
| (See https://lkml.org/lkml/2013/1/23/511) |
| B. Possibly support three zbuds per pageframe when space allows |
