linux-kernel - [PATCHv3 3/9] zsmalloc: move away from page order defines

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Date:   Thu, 27 Oct 2022 13:26:45 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>
Cc:     Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCHv3 3/9] zsmalloc: move away from page order defines

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@...omium.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 bc377e5d3417..d4f68fba746b 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;
 
-	max_pages_per_zspage = 1U << ZS_DEFAULT_PAGE_ORDER;
+	max_pages_per_zspage = ZS_DEFAULT_PAGES_PER_ZSPAGE;
 	/* min_alloc_size must be multiple of ZS_ALIGN */
 	pool->min_alloc_size = (max_pages_per_zspage << PAGE_SHIFT) >>
 		OBJ_INDEX_BITS;
-- 
2.38.0.135.g90850a2211-goog