diff options
Diffstat (limited to 'include/linux/mmzone.h')
| -rw-r--r-- | include/linux/mmzone.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index e050d68963a12..f5fa3082fd6a5 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -12,6 +12,7 @@ #include <linux/threads.h> #include <linux/numa.h> #include <linux/init.h> +#include <linux/seqlock.h> #include <asm/atomic.h> /* Free memory management - zoned buddy allocator. */ @@ -137,6 +138,10 @@ struct zone { * free areas of different sizes */ spinlock_t lock; +#ifdef CONFIG_MEMORY_HOTPLUG + /* see spanned/present_pages for more description */ + seqlock_t span_seqlock; +#endif struct free_area free_area[MAX_ORDER]; @@ -220,6 +225,16 @@ struct zone { /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */ unsigned long zone_start_pfn; + /* + * zone_start_pfn, spanned_pages and present_pages are all + * protected by span_seqlock. It is a seqlock because it has + * to be read outside of zone->lock, and it is done in the main + * allocator path. But, it is written quite infrequently. + * + * The lock is declared along with zone->lock because it is + * frequently read in proximity to zone->lock. It's good to + * give them a chance of being in the same cacheline. + */ unsigned long spanned_pages; /* total size, including holes */ unsigned long present_pages; /* amount of memory (excluding holes) */ |