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-rw-r--r--mm/z3fold.c26
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;
}
/**