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Diffstat (limited to 'Documentation/vm/z3fold.txt')
| -rw-r--r-- | Documentation/vm/z3fold.txt | 26 |
1 files changed, 0 insertions, 26 deletions
diff --git a/Documentation/vm/z3fold.txt b/Documentation/vm/z3fold.txt deleted file mode 100644 index 38e4dac810b62..0000000000000 --- a/Documentation/vm/z3fold.txt +++ /dev/null @@ -1,26 +0,0 @@ -z3fold ------- - -z3fold is 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. - -The main differences between z3fold and zbud are: -* unlike zbud, z3fold allows for up to PAGE_SIZE allocations -* z3fold can hold up to 3 compressed pages in its page -* z3fold doesn't export any API itself and is thus intended to be used - via the zpool API. - -To keep the determinism and simplicity, z3fold, just like zbud, always -stores an integral number of compressed pages per page, but it can store -up to 3 pages unlike zbud which can store at most 2. Therefore the -compression ratio goes to around 2.7x while zbud's one is around 1.7x. - -Unlike zbud (but like zsmalloc for that matter) z3fold_alloc() does not -return a dereferenceable pointer. Instead, it returns an unsigned long -handle which encodes actual location of the allocated object. - -Keeping effective compression ratio close to zsmalloc's, z3fold doesn't -depend on MMU enabled and provides more predictable reclaim behavior -which makes it a better fit for small and response-critical systems. |