On Thu 17-07-14 09:26:04, Johannes Weiner wrote:
> From bbe8c1645c77297a96ecd5d64d659ddcd6984d03 Mon Sep 17 00:00:00 2001
> From: Johannes Weiner <hannes@xxxxxxxxxxx>
> Date: Mon, 14 Jul 2014 08:51:54 -0400
> Subject: [patch] mm: vmscan: clean up struct scan_control
>
> Reorder the members by input and output, then turn the individual
> integers for may_writepage, may_unmap, may_swap, compaction_ready,
> hibernation_mode into bit fields to save stack space:
>
> +72/-296 -224
> kswapd 104 176 +72
> try_to_free_pages 80 56 -24
> try_to_free_mem_cgroup_pages 80 56 -24
> shrink_all_memory 88 64 -24
> reclaim_clean_pages_from_list 168 144 -24
> mem_cgroup_shrink_node_zone 104 80 -24
> __zone_reclaim 176 152 -24
> balance_pgdat 152 - -152
>
> Suggested-by: Mel Gorman <mgorman@xxxxxxx>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Looks nice to me.
Acked-by: Michal Hocko <mhocko@xxxxxxx>
> ---
> mm/vmscan.c | 99 ++++++++++++++++++++++++++++---------------------------------
> 1 file changed, 46 insertions(+), 53 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c28b8981e56a..81dd858b9d17 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -59,35 +59,20 @@
> #include <trace/events/vmscan.h>
>
> struct scan_control {
> - /* Incremented by the number of inactive pages that were scanned */
> - unsigned long nr_scanned;
> -
> - /* Number of pages freed so far during a call to shrink_zones() */
> - unsigned long nr_reclaimed;
> -
> - /* One of the zones is ready for compaction */
> - int compaction_ready;
> -
> /* How many pages shrink_list() should reclaim */
> unsigned long nr_to_reclaim;
>
> - unsigned long hibernation_mode;
> -
> /* This context's GFP mask */
> gfp_t gfp_mask;
>
> - int may_writepage;
> -
> - /* Can mapped pages be reclaimed? */
> - int may_unmap;
> -
> - /* Can pages be swapped as part of reclaim? */
> - int may_swap;
> -
> + /* Allocation order */
> int order;
>
> - /* Scan (total_size >> priority) pages at once */
> - int priority;
> + /*
> + * Nodemask of nodes allowed by the caller. If NULL, all nodes
> + * are scanned.
> + */
> + nodemask_t *nodemask;
>
> /*
> * The memory cgroup that hit its limit and as a result is the
> @@ -95,11 +80,27 @@ struct scan_control {
> */
> struct mem_cgroup *target_mem_cgroup;
>
> - /*
> - * Nodemask of nodes allowed by the caller. If NULL, all nodes
> - * are scanned.
> - */
> - nodemask_t *nodemask;
> + /* Scan (total_size >> priority) pages at once */
> + int priority;
> +
> + unsigned int may_writepage:1;
> +
> + /* Can mapped pages be reclaimed? */
> + unsigned int may_unmap:1;
> +
> + /* Can pages be swapped as part of reclaim? */
> + unsigned int may_swap:1;
> +
> + unsigned int hibernation_mode:1;
> +
> + /* One of the zones is ready for compaction */
> + unsigned int compaction_ready:1;
> +
> + /* Incremented by the number of inactive pages that were scanned */
> + unsigned long nr_scanned;
> +
> + /* Number of pages freed so far during a call to shrink_zones() */
> + unsigned long nr_reclaimed;
> };
>
> #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
> @@ -2668,15 +2669,14 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> {
> unsigned long nr_reclaimed;
> struct scan_control sc = {
> + .nr_to_reclaim = SWAP_CLUSTER_MAX,
> .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
> + .order = order,
> + .nodemask = nodemask,
> + .priority = DEF_PRIORITY,
> .may_writepage = !laptop_mode,
> - .nr_to_reclaim = SWAP_CLUSTER_MAX,
> .may_unmap = 1,
> .may_swap = 1,
> - .order = order,
> - .priority = DEF_PRIORITY,
> - .target_mem_cgroup = NULL,
> - .nodemask = nodemask,
> };
>
> /*
> @@ -2706,14 +2706,11 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
> unsigned long *nr_scanned)
> {
> struct scan_control sc = {
> - .nr_scanned = 0,
> .nr_to_reclaim = SWAP_CLUSTER_MAX,
> + .target_mem_cgroup = memcg,
> .may_writepage = !laptop_mode,
> .may_unmap = 1,
> .may_swap = !noswap,
> - .order = 0,
> - .priority = 0,
> - .target_mem_cgroup = memcg,
> };
> struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
> int swappiness = mem_cgroup_swappiness(memcg);
> @@ -2748,16 +2745,14 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
> unsigned long nr_reclaimed;
> int nid;
> struct scan_control sc = {
> - .may_writepage = !laptop_mode,
> - .may_unmap = 1,
> - .may_swap = !noswap,
> .nr_to_reclaim = SWAP_CLUSTER_MAX,
> - .order = 0,
> - .priority = DEF_PRIORITY,
> - .target_mem_cgroup = memcg,
> - .nodemask = NULL, /* we don't care the placement */
> .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
> (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
> + .target_mem_cgroup = memcg,
> + .priority = DEF_PRIORITY,
> + .may_writepage = !laptop_mode,
> + .may_unmap = 1,
> + .may_swap = !noswap,
> };
>
> /*
> @@ -3015,12 +3010,11 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
> unsigned long nr_soft_scanned;
> struct scan_control sc = {
> .gfp_mask = GFP_KERNEL,
> + .order = order,
> .priority = DEF_PRIORITY,
> + .may_writepage = !laptop_mode,
> .may_unmap = 1,
> .may_swap = 1,
> - .may_writepage = !laptop_mode,
> - .order = order,
> - .target_mem_cgroup = NULL,
> };
> count_vm_event(PAGEOUTRUN);
>
> @@ -3401,14 +3395,13 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
> {
> struct reclaim_state reclaim_state;
> struct scan_control sc = {
> + .nr_to_reclaim = nr_to_reclaim,
> .gfp_mask = GFP_HIGHUSER_MOVABLE,
> - .may_swap = 1,
> - .may_unmap = 1,
> + .priority = DEF_PRIORITY,
> .may_writepage = 1,
> - .nr_to_reclaim = nr_to_reclaim,
> + .may_unmap = 1,
> + .may_swap = 1,
> .hibernation_mode = 1,
> - .order = 0,
> - .priority = DEF_PRIORITY,
> };
> struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
> struct task_struct *p = current;
> @@ -3588,13 +3581,13 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
> struct task_struct *p = current;
> struct reclaim_state reclaim_state;
> struct scan_control sc = {
> - .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
> - .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
> - .may_swap = 1,
> .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
> .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
> .order = order,
> .priority = ZONE_RECLAIM_PRIORITY,
> + .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
> + .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
> + .may_swap = 1,
> };
> struct shrink_control shrink = {
> .gfp_mask = sc.gfp_mask,
> --
> 2.0.0
>
--
Michal Hocko
SUSE Labs
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