diff options
Diffstat (limited to 'mm/z3fold.c')
| -rw-r--r-- | mm/z3fold.c | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index 98ab01f910bc..be8b56e21c2d 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -268,6 +268,7 @@ static inline void *mchunk_memmove(struct z3fold_header *zhdr, zhdr->middle_chunks << CHUNK_SHIFT); } +#define BIG_CHUNK_GAP 3 /* Has to be called with lock held */ static int z3fold_compact_page(struct z3fold_header *zhdr) { @@ -286,8 +287,31 @@ static int z3fold_compact_page(struct z3fold_header *zhdr) zhdr->middle_chunks = 0; zhdr->start_middle = 0; zhdr->first_num++; + return 1; } - return 1; + + /* + * moving data is expensive, so let's only do that if + * there's substantial gain (at least BIG_CHUNK_GAP chunks) + */ + if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 && + zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >= + BIG_CHUNK_GAP) { + mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS); + zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS; + return 1; + } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 && + TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle + + zhdr->middle_chunks) >= + BIG_CHUNK_GAP) { + unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks - + zhdr->middle_chunks; + mchunk_memmove(zhdr, new_start); + zhdr->start_middle = new_start; + return 1; + } + + return 0; } /** |