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SubjectRe: [PATCH 2/2] mm: Make flags of unsigned type in struct shrinker
On Thu 19-07-18 13:51:27, Kirill Tkhai wrote:
> Currently, there are two flags only, so unsigned
> is more then enough. Also, move int seeks to keep
> these fields together.

a slightly more explanation _why_ would be really helpful. I suspect
this is to pack the structure better,

struct shrinker {
long unsigned int (*count_objects)(struct shrinker *, struct shrink_control *); /* 0 8 */
long unsigned int (*scan_objects)(struct shrinker *, struct shrink_control *); /* 8 8 */
int seeks; /* 16 4 */

/* XXX 4 bytes hole, try to pack */

long int batch; /* 24 8 */
long unsigned int flags; /* 32 8 */
struct list_head list; /* 40 16 */
atomic_long_t * nr_deferred; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */

/* size: 64, cachelines: 1, members: 7 */
/* sum members: 60, holes: 1, sum holes: 4 */
};

suggests so. Which is a good thing.

> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>

other than that looks reasonable to me
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> include/linux/shrinker.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
> index d58aaaed34a4..9443cafd1969 100644
> --- a/include/linux/shrinker.h
> +++ b/include/linux/shrinker.h
> @@ -63,9 +63,9 @@ struct shrinker {
> unsigned long (*scan_objects)(struct shrinker *,
> struct shrink_control *sc);
>
> - int seeks; /* seeks to recreate an obj */
> long batch; /* reclaim batch size, 0 = default */
> - unsigned long flags;
> + int seeks; /* seeks to recreate an obj */
> + unsigned flags;
>
> /* These are for internal use */
> struct list_head list;

--
Michal Hocko
SUSE Labs

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