On 10/5/20 2:59 PM, Michal Hocko wrote:
On Tue 22-09-20 16:37:06, Vlastimil Babka wrote:
We initialize boot-time pagesets with setup_pageset(), which sets high and
batch values that effectively disable pcplists.
We can remove this wrapper if we just set these values for all pagesets in
pageset_init(). Non-boot pagesets then subsequently update them to the proper
values.
No functional change.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/page_alloc.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 26069c8d1b19..76c2b4578723 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);
+static void pageset_init(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));
+ pageset_init(&per_cpu(boot_pageset, cpu));
mminit_verify_zonelist();
cpuset_init_current_mems_allowed();
@@ -6210,12 +6210,15 @@ static void pageset_init(struct per_cpu_pageset *p)
pcp = &p->pcp;
for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++)
INIT_LIST_HEAD(&pcp->lists[migratetype]);
-}
-static void setup_pageset(struct per_cpu_pageset *p)
-{
- pageset_init(p);
- pageset_update(&p->pcp, 0, 1);
+ /*
+ * Set batch and high values safe for a boot pageset. A true percpu
+ * pageset's initialization will update them subsequently. Here we don't
+ * need to be as careful as pageset_update() as nobody can access the
+ * pageset yet.
Isn't this slightly misleading? pageset_init is called from setup_zone_pageset
which is called from the memory hotplug as well. Isn't this more about
It is.
early zone initialization rather than boot pagesets? Or am I misreading
the patch?
It's for boot pagesets (call from build_all_zonelists_init()) that we need these
particular values (well, just high = 0). For early zone initialization during
hotplug the values don't matter as the caller is setup_zone_pageset() who
immediately replaces the values by zone_set_pageset_high_and_batch(). Which is
what the comment tries to say.
+ */
+ pcp->high = 0;
+ pcp->batch = 1;
}
/*
--
2.28.0
