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mm/slab: make calculate_alignment() function static

PATCH Applied Byongho Lee 2 participants 2 messages Dec 9, 2017 – Dec 10, 2017

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PATCH 1/1 mm/slab: make calculate_alignment() function static

calculate_alignment() function is only used inside 'slab_common.c'. So make it static and let compiler do more optimizations.

After this patch there's small improvements in 'text' and 'data' size.

$ gcc --version
  gcc (GCC) 7.2.1 20171128

Before:
text data bss dec hex filename
9890457 3828702 1212364 14931523 e3d643 vmlinux

After:
text data bss dec hex filename
9890437 3828670 1212364 14931471 e3d60f vmlinux

Also I fixed a 'style problem' reported by 'scripts/checkpatch.pl'.

WARNING: Missing a blank line after declarations #53: FILE: mm/slab_common.c:286:
+ unsigned long ralign = cache_line_size();
+ while (size <= ralign / 2)

---
 mm/slab.h        |  3 ---
 mm/slab_common.c | 56 +++++++++++++++++++++++++++++---------------------------
 2 files changed, 29 insertions(+), 30 deletions(-)
mm/slab.h +0 -3
index 028cdc7df67e..e894889dc24a 100644
@@ -79,9 +79,6 @@ extern const struct kmalloc_info_struct {
 	unsigned long size;
 } kmalloc_info[];
 
-unsigned long calculate_alignment(unsigned long flags,
-		unsigned long align, unsigned long size);
-
 #ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
 void setup_kmalloc_cache_index_table(void);
mm/slab_common.c +29 -27

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Signature · 7 lines
2.15.1

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Acked-by on v1 1/1
#1 lore raw
Quoted 16 lines · Byongho Lee

calculate_alignment() function is only used inside 'slab_common.c'. So make it static and let compiler do more optimizations.

After this patch there's small improvements in 'text' and 'data' size.

$ gcc --version
  gcc (GCC) 7.2.1 20171128

Before:
text data bss dec hex filename
9890457 3828702 1212364 14931523 e3d643 vmlinux

After:
text data bss dec hex filename
9890437 3828670 1212364 14931471 e3d60f vmlinux

Quoted 8 lines

Also I fixed a 'style problem' reported by 'scripts/checkpatch.pl'.

WARNING: Missing a blank line after declarations #53: FILE: mm/slab_common.c:286:
+ unsigned long ralign = cache_line_size();
+ while (size <= ralign / 2)

Quoted 101 lines
---
 mm/slab.h        |  3 ---
 mm/slab_common.c | 56 +++++++++++++++++++++++++++++---------------------------
 2 files changed, 29 insertions(+), 30 deletions(-)
mm/slab.h +0 -3
index 028cdc7df67e..e894889dc24a 100644
@@ -79,9 +79,6 @@ extern const struct kmalloc_info_struct {
 	unsigned long size;
 } kmalloc_info[];
 
-unsigned long calculate_alignment(unsigned long flags,
-		unsigned long align, unsigned long size);
-
 #ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
 void setup_kmalloc_cache_index_table(void);
mm/slab_common.c +29 -27
index 0d7fe71ff5e4..d25e7b56e20b 100644
@@ -267,6 +267,35 @@ static inline void memcg_unlink_cache(struct kmem_cache *s)
 }
 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */
 
+/*
+ * Figure out what the alignment of the objects will be given a set of
+ * flags, a user specified alignment and the size of the objects.
+ */
+static unsigned long calculate_alignment(unsigned long flags,
+		unsigned long align, unsigned long size)
+{
+	/*
+	 * If the user wants hardware cache aligned objects then follow that
+	 * suggestion if the object is sufficiently large.
+	 *
+	 * The hardware cache alignment cannot override the specified
+	 * alignment though. If that is greater then use it.
+	 */
+	if (flags & SLAB_HWCACHE_ALIGN) {
+		unsigned long ralign;
+
+		ralign = cache_line_size();
+		while (size <= ralign / 2)
+			ralign /= 2;
+		align = max(align, ralign);
+	}
+
+	if (align < ARCH_SLAB_MINALIGN)
+		align = ARCH_SLAB_MINALIGN;
+
+	return ALIGN(align, sizeof(void *));
+}
+
 /*
  * Find a mergeable slab cache
  */
@@ -337,33 +366,6 @@ struct kmem_cache *find_mergeable(size_t size, size_t align,
 	return NULL;
 }
 
-/*
- * Figure out what the alignment of the objects will be given a set of
- * flags, a user specified alignment and the size of the objects.
- */
-unsigned long calculate_alignment(unsigned long flags,
-		unsigned long align, unsigned long size)
-{
-	/*
-	 * If the user wants hardware cache aligned objects then follow that
-	 * suggestion if the object is sufficiently large.
-	 *
-	 * The hardware cache alignment cannot override the specified
-	 * alignment though. If that is greater then use it.
-	 */
-	if (flags & SLAB_HWCACHE_ALIGN) {
-		unsigned long ralign = cache_line_size();
-		while (size <= ralign / 2)
-			ralign /= 2;
-		align = max(align, ralign);
-	}
-
-	if (align < ARCH_SLAB_MINALIGN)
-		align = ARCH_SLAB_MINALIGN;
-
-	return ALIGN(align, sizeof(void *));
-}
-
 static struct kmem_cache *create_cache(const char *name,
 		size_t object_size, size_t size, size_t align,
 		unsigned long flags, void (*ctor)(void *),
Signature · 7 lines
2.15.1

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Signature · 8 lines
Michal Hocko
SUSE Labs

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