No off-cpu users of the percpu pagesets exist.
zone_pcp_update()'s goal is to adjust the ->high and ->mark members of a
percpu pageset based on a zone's ->managed_pages. We don't need to drain
the entire percpu pageset just to modify these fields. Avoid calling
setup_pageset() (and the draining required to call it) and instead just
set the fields' values.
This does change the behavior of zone_pcp_update() as the percpu
pagesets will not be drained when zone_pcp_update() is called (they will
end up being shrunk, not completely drained, later when a 0-order page
is freed in free_hot_cold_page()).
Signed-off-by: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5877cf0..48f2faa 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5987,32 +5987,22 @@ void free_contig_range(unsigned long pfn, unsigned nr_pages)
#endif
#ifdef CONFIG_MEMORY_HOTPLUG
-static int __meminit __zone_pcp_update(void *data)
+static void __meminit __zone_pcp_update(void *data)
{
struct zone *zone = data;
- int cpu;
- unsigned long batch = zone_batchsize(zone), flags;
-
- for_each_possible_cpu(cpu) {
- struct per_cpu_pageset *pset;
- struct per_cpu_pages *pcp;
-
- pset = per_cpu_ptr(zone->pageset, cpu);
- pcp = &pset->pcp;
-
- local_irq_save(flags);
- if (pcp->count > 0)
- free_pcppages_bulk(zone, pcp->count, pcp);
- drain_zonestat(zone, pset);
- setup_pageset(pset, batch);
- local_irq_restore(flags);
- }
- return 0;
+ unsigned long batch = zone_batchsize(zone);
+ struct per_cpu_pageset *pset =
+ per_cpu_ptr(zone->pageset, smp_processor_id());
+ pageset_set_batch(pset, batch);
}
+/*
+ * The zone indicated has a new number of managed_pages; batch sizes and percpu
+ * page high values need to be recalulated.
+ */
void __meminit zone_pcp_update(struct zone *zone)
{
- stop_machine(__zone_pcp_update, zone, NULL);
+ on_each_cpu(__zone_pcp_update, zone, true);
}
#endif
--
1.8.2
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