From: KOSAKI Motohiro on
Changelog
from v1
- get_anon_scan_ratio don't tak zone->lru_lock anymore
because zoneinfo_show_print takes zone->lock.


======================================
Vmscan folks was asked "why does my system makes so much swap-out?"
in lkml at several times.
At that time, I made the debug patch to show recent_anon_{scanned/rorated}
parameter at least three times.

Thus, its parameter should be showed on /proc/zoneinfo. It help
vmscan folks debugging.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel(a)redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com>
---
include/linux/swap.h | 2 ++
mm/vmscan.c | 50 ++++++++++++++++++++++++++++++++++++--------------
mm/vmstat.c | 7 +++++--
3 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index a2602a8..e95d7ed 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -280,6 +280,8 @@ extern void scan_unevictable_unregister_node(struct node *node);
extern int kswapd_run(int nid);
extern void kswapd_stop(int nid);

+unsigned long get_anon_scan_ratio(struct zone *zone, struct mem_cgroup *memcg, int swappiness);
+
#ifdef CONFIG_MMU
/* linux/mm/shmem.c */
extern int shmem_unuse(swp_entry_t entry, struct page *page);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 640486b..0900931 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1493,8 +1493,8 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
* percent[0] specifies how much pressure to put on ram/swap backed
* memory, while percent[1] determines pressure on the file LRUs.
*/
-static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
- unsigned long *percent)
+static void __get_scan_ratio(struct zone *zone, struct scan_control *sc,
+ int need_update, unsigned long *percent)
{
unsigned long anon, file, free;
unsigned long anon_prio, file_prio;
@@ -1535,18 +1535,19 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
*
* anon in [0], file in [1]
*/
- if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
- spin_lock_irq(&zone->lru_lock);
- reclaim_stat->recent_scanned[0] /= 2;
- reclaim_stat->recent_rotated[0] /= 2;
- spin_unlock_irq(&zone->lru_lock);
- }
-
- if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
- spin_lock_irq(&zone->lru_lock);
- reclaim_stat->recent_scanned[1] /= 2;
- reclaim_stat->recent_rotated[1] /= 2;
- spin_unlock_irq(&zone->lru_lock);
+ if (need_update) {
+ if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
+ spin_lock_irq(&zone->lru_lock);
+ reclaim_stat->recent_scanned[0] /= 2;
+ reclaim_stat->recent_rotated[0] /= 2;
+ spin_unlock_irq(&zone->lru_lock);
+ }
+ if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
+ spin_lock_irq(&zone->lru_lock);
+ reclaim_stat->recent_scanned[1] /= 2;
+ reclaim_stat->recent_rotated[1] /= 2;
+ spin_unlock_irq(&zone->lru_lock);
+ }
}

/*
@@ -1572,6 +1573,27 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
percent[1] = 100 - percent[0];
}

+static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
+ unsigned long *percent)
+{
+ __get_scan_ratio(zone, sc, 1, percent);
+}
+
+unsigned long get_anon_scan_ratio(struct zone *zone, struct mem_cgroup *memcg, int swappiness)
+{
+ unsigned long percent[2];
+ struct scan_control sc = {
+ .may_swap = 1,
+ .swappiness = swappiness,
+ .mem_cgroup = memcg,
+ };
+
+ __get_scan_ratio(zone, &sc, 0, percent);
+
+ return percent[0];
+}
+
+
/*
* Smallish @nr_to_scan's are deposited in @nr_saved_scan,
* until we collected @swap_cluster_max pages to scan.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6051fba..f690117 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -15,6 +15,7 @@
#include <linux/cpu.h>
#include <linux/vmstat.h>
#include <linux/sched.h>
+#include <linux/swap.h>

#ifdef CONFIG_VM_EVENT_COUNTERS
DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
@@ -760,11 +761,13 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
"\n all_unreclaimable: %u"
"\n prev_priority: %i"
"\n start_pfn: %lu"
- "\n inactive_ratio: %u",
+ "\n inactive_ratio: %u"
+ "\n anon_scan_ratio: %lu",
zone_is_all_unreclaimable(zone),
zone->prev_priority,
zone->zone_start_pfn,
- zone->inactive_ratio);
+ zone->inactive_ratio,
+ get_anon_scan_ratio(zone, NULL, vm_swappiness));
seq_putc(m, '\n');
}

--
1.6.5.2



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