[RFC][PATCH 6/9] mm/vmscan: add page demotion counter

Dave Hansen
2020-10-07T16:18:10Z

From: Yang Shi <yang.shi@linux.alibaba.com>

Account the number of demoted pages into reclaim_state->nr_demoted.

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

[ daveh:
- __count_vm_events() a bit, and made them look at the THP
size directly rather than getting data from migrate_pages()
]

Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
---

b/include/linux/vm_event_item.h | 2 ++
b/mm/vmscan.c | 6 ++++++
b/mm/vmstat.c | 2 ++
3 files changed, 10 insertions(+)

diff -puN include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter include/linux/vm_event_item.h
--- a/include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter 2020-10-07 09:15:32.171642439 -0700
+++ b/include/linux/vm_event_item.h 2020-10-07 09:15:32.179642439 -0700
@@ -33,6 +33,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
PGREUSE,
PGSTEAL_KSWAPD,
PGSTEAL_DIRECT,
+ PGDEMOTE_KSWAPD,
+ PGDEMOTE_DIRECT,
PGSCAN_KSWAPD,
PGSCAN_DIRECT,
PGSCAN_DIRECT_THROTTLE,
diff -puN mm/vmscan.c~mm-vmscan-add-page-demotion-counter mm/vmscan.c
--- a/mm/vmscan.c~mm-vmscan-add-page-demotion-counter 2020-10-07 09:15:32.173642439 -0700
+++ b/mm/vmscan.c 2020-10-07 09:15:32.180642439 -0700
@@ -147,6 +147,7 @@ struct scan_control {
unsigned int immediate;
unsigned int file_taken;
unsigned int taken;
+ unsigned int demoted;
} nr;

/* for recording the reclaimed slab by now */
@@ -1134,6 +1135,11 @@ static unsigned int demote_page_list(str
target_nid, MIGRATE_ASYNC, MR_DEMOTION,
&nr_succeeded);

+ if (current_is_kswapd())
+ __count_vm_events(PGDEMOTE_KSWAPD, nr_succeeded);
+ else
+ __count_vm_events(PGDEMOTE_DIRECT, nr_succeeded);
+
return nr_succeeded;
}

diff -puN mm/vmstat.c~mm-vmscan-add-page-demotion-counter mm/vmstat.c
--- a/mm/vmstat.c~mm-vmscan-add-page-demotion-counter 2020-10-07 09:15:32.175642439 -0700
+++ b/mm/vmstat.c 2020-10-07 09:15:32.181642439 -0700
@@ -1244,6 +1244,8 @@ const char * const vmstat_text[] = {
"pgreuse",
"pgsteal_kswapd",
"pgsteal_direct",
+ "pgdemote_kswapd",
+ "pgdemote_direct",
"pgscan_kswapd",
"pgscan_direct",
"pgscan_direct_throttle",
_