[PATCH 07/10] mm: vmscan: add page demotion counter

Yang Shi
2019-03-23T04:46:03Z

Demoted pages are counted into reclaim_state->nr_demoted instead of
nr_reclaimed since they are not reclaimed actually. They are still in
memory, but just migrated to PMEM.

Add pgdemote_kswapd and pgdemote_direct VM counters showed in
/proc/vmstat.

Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
include/linux/vm_event_item.h | 2 ++
include/linux/vmstat.h | 1 +
mm/vmscan.c | 14 ++++++++++++++
mm/vmstat.c | 2 ++
4 files changed, 19 insertions(+)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 47a3441..499a3aa 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -32,6 +32,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
PGREFILL,
PGSTEAL_KSWAPD,
PGSTEAL_DIRECT,
+ PGDEMOTE_KSWAPD,
+ PGDEMOTE_DIRECT,
PGSCAN_KSWAPD,
PGSCAN_DIRECT,
PGSCAN_DIRECT_THROTTLE,
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 2db8d60..eb5d21c 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -29,6 +29,7 @@ struct reclaim_stat {
unsigned nr_activate;
unsigned nr_ref_keep;
unsigned nr_unmap_fail;
+ unsigned nr_demoted;
};

#ifdef CONFIG_VM_EVENT_COUNTERS
diff --git a/mm/vmscan.c b/mm/vmscan.c
index bdcab6b..3c7ba7e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1286,6 +1286,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,

if (has_nonram_online()) {
list_add(&page->lru, &demote_pages);
+ if (PageTransHuge(page))
+ stat->nr_demoted += HPAGE_PMD_NR;
+ else
+ stat->nr_demoted++;
unlock_page(page);
continue;
}
@@ -1523,7 +1527,17 @@ static unsigned long shrink_page_list(struct list_head *page_list,
putback_movable_pages(&demote_pages);

list_splice(&ret_pages, &demote_pages);
+
+ if (err > 0)
+ stat->nr_demoted -= err;
+ else
+ stat->nr_demoted = 0;
}
+
+ if (current_is_kswapd())
+ __count_vm_events(PGDEMOTE_KSWAPD, stat->nr_demoted);
+ else
+ __count_vm_events(PGDEMOTE_DIRECT, stat->nr_demoted);
}

mem_cgroup_uncharge_list(&free_pages);
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 36b56f8..0e863e7 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1192,6 +1192,8 @@ int fragmentation_index(struct zone *zone, unsigned int order)
"pgrefill",
"pgsteal_kswapd",
"pgsteal_direct",
+ "pgdemote_kswapd",
+ "pgdemote_direct",
"pgscan_kswapd",
"pgscan_direct",
"pgscan_direct_throttle",
--
1.8.3.1