If zswap pool fragment is heavy, it's meanless to store more pages to zswap.
So refuse allocate page to zswap pool to limit the fragmentation.
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
include/linux/zbud.h | 2 +-
mm/zbud.c | 4 +++-
mm/zswap.c | 15 +++++++++++++--
3 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/include/linux/zbud.h b/include/linux/zbud.h
index 2571a5c..71a61be 100644
--- a/include/linux/zbud.h
+++ b/include/linux/zbud.h
@@ -12,7 +12,7 @@ struct zbud_ops {
struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops);
void zbud_destroy_pool(struct zbud_pool *pool);
int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
- unsigned long *handle);
+ unsigned long *handle, bool dis_pagealloc);
void zbud_free(struct zbud_pool *pool, unsigned long handle);
int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries);
void *zbud_map(struct zbud_pool *pool, unsigned long handle);
diff --git a/mm/zbud.c b/mm/zbud.c
index 9bb4710..5ace447 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -248,7 +248,7 @@ void zbud_destroy_pool(struct zbud_pool *pool)
* a new page.
*/
int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
- unsigned long *handle)
+ unsigned long *handle, bool dis_pagealloc)
{
int chunks, i, freechunks;
struct zbud_header *zhdr = NULL;
@@ -279,6 +279,8 @@ int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
/* Couldn't find unbuddied zbud page, create new one */
spin_unlock(&pool->lock);
+ if (dis_pagealloc)
+ return -ENOSPC;
page = alloc_page(gfp);
if (!page)
return -ENOMEM;
diff --git a/mm/zswap.c b/mm/zswap.c
index deda2b6..7fe2b1b 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -607,10 +607,12 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
struct zswap_entry *entry, *dupentry;
int ret;
unsigned int dlen = PAGE_SIZE, len;
- unsigned long handle;
+ unsigned long handle, stored_pages;
char *buf;
u8 *src, *dst;
struct zswap_header *zhdr;
+ u64 tmp;
+ bool dis_pagealloc = false;
if (!tree) {
ret = -ENODEV;
@@ -645,10 +647,19 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
goto freepage;
}
+ /* If the fragment of zswap pool is heavy, don't alloc new page to
+ * zswap pool anymore. The limitation of fragment is 70% percent currently
+ */
+ stored_pages = atomic_read(&zswap_stored_pages);
+ tmp = zswap_pool_pages * 100;
+ do_div(tmp, stored_pages + 1);
+ if (tmp > 70)
+ dis_pagealloc = true;
+
/* store */
len = dlen + sizeof(struct zswap_header);
ret = zbud_alloc(tree->pool, len, __GFP_NORETRY | __GFP_NOWARN,
- &handle);
+ &handle, dis_pagealloc);
if (ret == -ENOSPC) {
zswap_reject_compress_poor++;
goto freepage;
--
1.7.10.4
--
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