[PATCH 1/9] mm, page_alloc: clean up pageset high and batch update

Vlastimil Babka
2020-09-22T14:37:30Z

The updates to pcplists' high and batch valued are handled by multiple
functions that make the calculations hard to follow. Consolidate everything
to pageset_set_high_and_batch() and remove pageset_set_batch() and
pageset_set_high() wrappers.

The only special case using one of the removed wrappers was:
build_all_zonelists_init()
setup_pageset()
pageset_set_batch()
which was hardcoding batch as 0, so we can just open-code a call to
pageset_update() with constant parameters instead.

No functional change.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
mm/page_alloc.c | 49 ++++++++++++++++++++-----------------------------
1 file changed, 20 insertions(+), 29 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 60a0e94645a6..a163c5e561f2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5823,7 +5823,7 @@ static void build_zonelists(pg_data_t *pgdat)
* not check if the processor is online before following the pageset pointer.
* Other parts of the kernel may not check if the zone is available.
*/
-static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
+static void setup_pageset(struct per_cpu_pageset *p);
static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);

@@ -5891,7 +5891,7 @@ build_all_zonelists_init(void)
* (a chicken-egg dilemma).
*/
for_each_possible_cpu(cpu)
- setup_pageset(&per_cpu(boot_pageset, cpu), 0);
+ setup_pageset(&per_cpu(boot_pageset, cpu));

mminit_verify_zonelist();
cpuset_init_current_mems_allowed();
@@ -6200,12 +6200,6 @@ static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
pcp->batch = batch;
}

-/* a companion to pageset_set_high() */
-static void pageset_set_batch(struct per_cpu_pageset *p, unsigned long batch)
-{
- pageset_update(&p->pcp, 6 * batch, max(1UL, 1 * batch));
-}
-
static void pageset_init(struct per_cpu_pageset *p)
{
struct per_cpu_pages *pcp;
@@ -6218,35 +6212,32 @@ static void pageset_init(struct per_cpu_pageset *p)
INIT_LIST_HEAD(&pcp->lists[migratetype]);
}

-static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
+static void setup_pageset(struct per_cpu_pageset *p)
{
pageset_init(p);
- pageset_set_batch(p, batch);
+ pageset_update(&p->pcp, 0, 1);
}

/*
- * pageset_set_high() sets the high water mark for hot per_cpu_pagelist
- * to the value high for the pageset p.
+ * Calculate and set new high and batch values for given per-cpu pageset of a
+ * zone, based on the zone's size and the percpu_pagelist_fraction sysctl.
*/
-static void pageset_set_high(struct per_cpu_pageset *p,
- unsigned long high)
-{
- unsigned long batch = max(1UL, high / 4);
- if ((high / 4) > (PAGE_SHIFT * 8))
- batch = PAGE_SHIFT * 8;
-
- pageset_update(&p->pcp, high, batch);
-}
-
static void pageset_set_high_and_batch(struct zone *zone,
- struct per_cpu_pageset *pcp)
+ struct per_cpu_pageset *p)
{
- if (percpu_pagelist_fraction)
- pageset_set_high(pcp,
- (zone_managed_pages(zone) /
- percpu_pagelist_fraction));
- else
- pageset_set_batch(pcp, zone_batchsize(zone));
+ unsigned long new_high, new_batch;
+
+ if (percpu_pagelist_fraction) {
+ new_high = zone_managed_pages(zone) / percpu_pagelist_fraction;
+ new_batch = max(1UL, new_high / 4);
+ if ((new_high / 4) > (PAGE_SHIFT * 8))
+ new_batch = PAGE_SHIFT * 8;
+ } else {
+ new_batch = zone_batchsize(zone);
+ new_high = 6 * new_batch;
+ new_batch = max(1UL, 1 * new_batch);
+ }
+ pageset_update(&p->pcp, new_high, new_batch);
}

static void __meminit zone_pageset_init(struct zone *zone, int cpu)
--
2.28.0