From: Wei Yang <richard.weiyang@xxxxxxxxx> Subject: mm/slub.c: pack red_left_pad with another int to save a word Patch series "try to save some memory for kmem_cache in some cases", v2. 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. This patch (of 3): On 64bit arch, struct is 8-bytes aligned, so int will occupy a word if it doesn't sit well. This patch pack red_left_pad with reserved to save 8 bytes for struct kmem_cache on a 64bit arch. Link: http://lkml.kernel.org/r/20170502144533.10729-2-richard.weiyang@xxxxxxxxx Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/slub_def.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN include/linux/slub_def.h~mm-slub-pack-red_left_pad-with-another-int-to-save-a-word include/linux/slub_def.h --- a/include/linux/slub_def.h~mm-slub-pack-red_left_pad-with-another-int-to-save-a-word +++ a/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 */ struct work_struct kobj_remove_work; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
