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[PATCH V2 0/3] try to save some memory for kmem_cache in some cases

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  [PATCH V2 0/3] try to save some memory for kmem_cache in some cases Wei Yang <richard.weiyang@gmail.com> - 2017-05-02 16:50 +0200
    [PATCH V2 1/3] mm/slub: pack red_left_pad with another int to save a word Wei Yang <richard.weiyang@gmail.com> - 2017-05-02 16:50 +0200

#1634465 — [PATCH V2 0/3] try to save some memory for kmem_cache in some cases

kmem_cache is a frequently used data in kernel. During the code reading, I
found maybe we could save some space in some cases.

1. On 64bit arch, type int will occupy a word if it doesn't sit well.
2. cpu_slab->partial is just used when CONFIG_SLUB_CPU_PARTIAL is set
3. cpu_partial is just used when CONFIG_SLUB_CPU_PARTIAL is set, while just
save some space on 32bit arch.

v2:
   define some macro to make the code more elegant

Wei Yang (3):
  mm/slub: pack red_left_pad with another int to save a word
  mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
  mm/slub: wrap kmem_cache->cpu_partial in config
    CONFIG_SLUB_CPU_PARTIAL

 include/linux/slub_def.h | 34 ++++++++++++++++++-
 mm/slub.c                | 85 ++++++++++++++++++++++++++----------------------
 2 files changed, 80 insertions(+), 39 deletions(-)

-- 
2.11.0

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#1634466 — [PATCH V2 1/3] mm/slub: pack red_left_pad with another int to save a word

On 64bit arch, struct is 8-bytes aligned, so int will occupy a word if it
doesn't sits well.

This patch pack red_left_pad with reserved to save 8 bytes for struct
kmem_cache on a 64bit arch.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 include/linux/slub_def.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 07ef550c6627..ec13aab32647 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -79,9 +79,9 @@ struct kmem_cache {
 	int inuse;		/* Offset to metadata */
 	int align;		/* Alignment */
 	int reserved;		/* Reserved bytes at the end of slabs */
+	int red_left_pad;	/* Left redzone padding size */
 	const char *name;	/* Name (only for display!) */
 	struct list_head list;	/* List of slab caches */
-	int red_left_pad;	/* Left redzone padding size */
 #ifdef CONFIG_SYSFS
 	struct kobject kobj;	/* For sysfs */
 #endif
-- 
2.11.0

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