Re: [PATCH] zsmalloc: reorganize struct size_class to pack 4 bytes hole

From: Sergey Senozhatsky
Date: Fri Dec 11 2015 - 01:21:14 EST


Cc linux-mm and linux-kernel

On (12/11/15 13:20), Weijie Yang wrote:
>
> Reoder the pages_per_zspage field in struct size_class which can eliminate
> the 4 bytes hole between it and stats field.
>

Looks good to me.

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>

> Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
> ---
> mm/zsmalloc.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 9f15bdd..e7414ce 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -213,10 +213,10 @@ struct size_class {
> int size;
> unsigned int index;
>
> - /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
> - int pages_per_zspage;
> struct zs_size_stat stats;
>
> + /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
> + int pages_per_zspage;
> /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
> bool huge;
> };


we also can re-order `struct zs_pool' -- `gfp_t flags' and `bool shrinker_enabled'
will be fine together.

I can send a separate patch of we can fold the one below.
I'm good either way.

---

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 9f15bdd..2a3af25 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -246,19 +246,17 @@ struct zs_pool {

struct size_class **size_class;
struct kmem_cache *handle_cachep;
-
- gfp_t flags; /* allocation flags used when growing pool */
- atomic_long_t pages_allocated;
-
struct zs_pool_stats stats;
-
- /* Compact classes */
- struct shrinker shrinker;
+ atomic_long_t pages_allocated;
+ /* allocation flags used when growing pool */
+ gfp_t flags;
/*
* To signify that register_shrinker() was successful
* and unregister_shrinker() will not Oops.
*/
bool shrinker_enabled;
+ /* Compact classes */
+ struct shrinker shrinker;
#ifdef CONFIG_ZSMALLOC_STAT
struct dentry *stat_dentry;
#endif

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