[PATCHv4 3/9] zsmalloc: move away from page order defines

Sergey Senozhatsky
2022-10-31T05:41:27Z

There is no reason for us to require pages per-zspage to be a
power of two. Rename macros and use plain limit numbers there
instead of 2 ^ N values. This will let us to have more tunable
limits.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
include/linux/zsmalloc.h | 16 +++++++---------
mm/zsmalloc.c | 4 +---
2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h
index 6cd1d95b928a..b6b8654a2d45 100644
--- a/include/linux/zsmalloc.h
+++ b/include/linux/zsmalloc.h
@@ -33,17 +33,15 @@ enum zs_mapmode {
*/
};

-#define ZS_PAGE_ORDER_2 2
-#define ZS_PAGE_ORDER_4 4
-
/*
- * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
- * pages. ZS_MAX_PAGE_ORDER defines upper limit on N, ZS_MIN_PAGE_ORDER
- * defines lower limit on N. ZS_DEFAULT_PAGE_ORDER is recommended value.
+ * A single 'zspage' is composed of up to N discontiguous 0-order
+ * (single) pages. ZS_MAX_PAGES_PER_ZSPAGE defines upper limit on N,
+ * ZS_MIN_PAGES_PER_ZSPAGE defines lower limit on N.
+ * ZS_DEFAULT_PAGES_PER_ZSPAGE is a recommended value.
*/
-#define ZS_MIN_PAGE_ORDER ZS_PAGE_ORDER_2
-#define ZS_MAX_PAGE_ORDER ZS_PAGE_ORDER_4
-#define ZS_DEFAULT_PAGE_ORDER ZS_PAGE_ORDER_2
+#define ZS_MIN_PAGES_PER_ZSPAGE 1
+#define ZS_MAX_PAGES_PER_ZSPAGE 16
+#define ZS_DEFAULT_PAGES_PER_ZSPAGE 4

struct zs_pool_stats {
/* How many pages were migrated (freed) */
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index a9773566f85b..5f79223e7bfe 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -74,8 +74,6 @@
*/
#define ZS_ALIGN 8

-#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_PAGE_ORDER)
-
#define ZS_HANDLE_SIZE (sizeof(unsigned long))

/*
@@ -2215,7 +2213,7 @@ struct zs_pool *zs_create_pool(const char *name)
if (!pool)
return NULL;

- num_pages = 1UL << ZS_DEFAULT_PAGE_ORDER;
+ num_pages = ZS_DEFAULT_PAGES_PER_ZSPAGE;
/* min_alloc_size must be multiple of ZS_ALIGN */
pool->min_alloc_size = num_pages << PAGE_SHIFT >> OBJ_INDEX_BITS;
pool->min_alloc_size = max(pool->min_alloc_size, ZS_MIN_ALLOC_SIZE);
--
2.38.1.273.g43a17bfeac-goog