Pages_allocated has counted in size_class structure and when user
want to see total_size_bytes, it gathers all of value from each
size_class to report the sum.
It's not bad if user don't see the value often but if user start
to see the value frequently, it would be not a good deal for
performance POV.
This patch moves the variable from size_class to zs_pool so it would
reduce memory footprint (from [255 * 8byte] to [sizeof(atomic_t)])
but it adds new locking overhead but it wouldn't be severe because
it's not a hot path in zs_malloc(ie, it is called only when new
zspage is created, not a object).
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
mm/zsmalloc.c | 30 ++++++++++++++++--------------
1 file changed, 16 insertions(+), 14 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index fe78189624cf..a6089bd26621 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -198,9 +198,6 @@ struct size_class {
spinlock_t lock;
- /* stats */
- u64 pages_allocated;
-
struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
};
@@ -216,9 +213,12 @@ struct link_free {
};
struct zs_pool {
+ spinlock_t stat_lock;
+
struct size_class size_class[ZS_SIZE_CLASSES];
gfp_t flags; /* allocation flags used when growing pool */
+ unsigned long pages_allocated;
};
/*
@@ -882,6 +882,7 @@ struct zs_pool *zs_create_pool(gfp_t flags)
}
+ spin_lock_init(&pool->stat_lock);
pool->flags = flags;
return pool;
@@ -943,8 +944,10 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
return 0;
set_zspage_mapping(first_page, class->index, ZS_EMPTY);
+ spin_lock(&pool->stat_lock);
+ pool->pages_allocated += class->pages_per_zspage;
+ spin_unlock(&pool->stat_lock);
spin_lock(&class->lock);
- class->pages_allocated += class->pages_per_zspage;
}
obj = (unsigned long)first_page->freelist;
@@ -997,14 +1000,14 @@ void zs_free(struct zs_pool *pool, unsigned long obj)
first_page->inuse--;
fullness = fix_fullness_group(pool, first_page);
-
- if (fullness == ZS_EMPTY)
- class->pages_allocated -= class->pages_per_zspage;
-
spin_unlock(&class->lock);
- if (fullness == ZS_EMPTY)
+ if (fullness == ZS_EMPTY) {
+ spin_lock(&pool->stat_lock);
+ pool->pages_allocated -= class->pages_per_zspage;
+ spin_unlock(&pool->stat_lock);
free_zspage(first_page);
+ }
}
EXPORT_SYMBOL_GPL(zs_free);
@@ -1100,12 +1103,11 @@ EXPORT_SYMBOL_GPL(zs_unmap_object);
u64 zs_get_total_size_bytes(struct zs_pool *pool)
{
- int i;
- u64 npages = 0;
-
- for (i = 0; i < ZS_SIZE_CLASSES; i++)
- npages += pool->size_class[i].pages_allocated;
+ u64 npages;
+ spin_lock(&pool->stat_lock);
+ npages = pool->pages_allocated;
+ spin_unlock(&pool->stat_lock);
return npages << PAGE_SHIFT;
}
EXPORT_SYMBOL_GPL(zs_get_total_size_bytes);
--
2.0.0
--
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