On Mon 05-01-15 18:17:43, Vlastimil Babka wrote:
> The function next_zones_zonelist() returns zoneref pointer, as well as zone
> pointer via extra parameter. Since the latter can be trivially obtained by
> dereferencing the former, the overhead of the extra parameter is unjustified.
>
> This patch thus removes the zone parameter from next_zones_zonelist(). Both
> callers happen to be in the same header file, so it's simple to add the
> zoneref dereference inline. We save some bytes of code size.
Dunno. It makes first_zones_zonelist and next_zones_zonelist look
different which might be a bit confusing. It's not a big deal but
I am not sure it is worth it.
> add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-96 (-96)
> function old new delta
> __alloc_pages_nodemask 2182 2176 -6
> nr_free_zone_pages 129 115 -14
> get_page_from_freelist 2652 2576 -76
>
> add/remove: 0/0 grow/shrink: 1/0 up/down: 10/0 (10)
> function old new delta
> try_to_compact_pages 569 579 +10
>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> ---
> include/linux/mmzone.h | 13 +++++++------
> mm/mmzone.c | 4 +---
> 2 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 2f0856d..a2884ef 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -970,7 +970,6 @@ static inline int zonelist_node_idx(struct zoneref *zoneref)
> * @z - The cursor used as a starting point for the search
> * @highest_zoneidx - The zone index of the highest zone to return
> * @nodes - An optional nodemask to filter the zonelist with
> - * @zone - The first suitable zone found is returned via this parameter
> *
> * This function returns the next zone at or below a given zone index that is
> * within the allowed nodemask using a cursor as the starting point for the
> @@ -980,8 +979,7 @@ static inline int zonelist_node_idx(struct zoneref *zoneref)
> */
> struct zoneref *next_zones_zonelist(struct zoneref *z,
> enum zone_type highest_zoneidx,
> - nodemask_t *nodes,
> - struct zone **zone);
> + nodemask_t *nodes);
>
> /**
> * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
> @@ -1000,8 +998,10 @@ static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
> nodemask_t *nodes,
> struct zone **zone)
> {
> - return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
> - zone);
> + struct zoneref *z = next_zones_zonelist(zonelist->_zonerefs,
> + highest_zoneidx, nodes);
> + *zone = zonelist_zone(z);
> + return z;
> }
>
> /**
> @@ -1018,7 +1018,8 @@ static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
> #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
> for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
> zone; \
> - z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
> + z = next_zones_zonelist(++z, highidx, nodemask), \
> + zone = zonelist_zone(z)) \
>
> /**
> * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
> diff --git a/mm/mmzone.c b/mm/mmzone.c
> index bf34fb8..7d87ebb 100644
> --- a/mm/mmzone.c
> +++ b/mm/mmzone.c
> @@ -54,8 +54,7 @@ static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
> /* Returns the next zone at or below highest_zoneidx in a zonelist */
> struct zoneref *next_zones_zonelist(struct zoneref *z,
> enum zone_type highest_zoneidx,
> - nodemask_t *nodes,
> - struct zone **zone)
> + nodemask_t *nodes)
> {
> /*
> * Find the next suitable zone to use for the allocation.
> @@ -69,7 +68,6 @@ struct zoneref *next_zones_zonelist(struct zoneref *z,
> (z->zone && !zref_in_nodemask(z, nodes)))
> z++;
>
> - *zone = zonelist_zone(z);
> return z;
> }
>
> --
> 2.1.2
>
--
Michal Hocko
SUSE Labs
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