This patch addresses TODO featuring in original version :
"Make the window size depend on machine size, as we do for vmstat"
It initializes vmpressure_win in vmstat using calculate_normal_threshold()
based on each zone/cpu * SWAP_CLUSTER_SIZE instead of
static SWAP_CLUSTER_MAX * 16 = 512
Some values :
CPU MB VMPRESSURE
8 512 1024
1 1024 320
2 1024 640
2 2048 768
4 2048 1152
1 4096 640
4 4096 1920
...
(No maximum vmpressure value currently defined)
cf mm/vmstat.c: calculate_normal_threshold for further values
vmpressure_win is refreshed through cpu notifier and exposed read-only in
/proc/sys/vm/vmpressure_win
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Davidlohr Bueso <davidlohr@xxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: cgroups@xxxxxxxxxxxxxxx
Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>
---
V3:
-Further description
-sysctl handler / ulong
-Cc list
V2: Suggestions by Andrew Morton
-Expose vmpressure_win
-Remove spinlock
include/linux/swap.h | 4 ++++
kernel/sysctl.c | 9 +++++++++
mm/vmpressure.c | 4 +---
mm/vmstat.c | 6 ++++++
4 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 3507115..886897d 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -354,6 +354,10 @@ extern int vm_swappiness;
extern int remove_mapping(struct address_space *mapping, struct page *page);
extern unsigned long vm_total_pages;
+#ifdef CONFIG_MEMCG
+extern unsigned long vmpressure_win;
+#endif
+
#ifdef CONFIG_NUMA
extern int zone_reclaim_mode;
extern int sysctl_min_unmapped_ratio;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 74f5b58..c0c5ea6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1202,6 +1202,15 @@ static struct ctl_table vm_table[] = {
.mode = 0444 /* read-only */,
.proc_handler = pdflush_proc_obsolete,
},
+#ifdef CONFIG_MEMCG
+ {
+ .procname = "vmpressure_window",
+ .data = &vmpressure_win,
+ .maxlen = sizeof(vmpressure_win),
+ .mode = 0444,
+ .proc_handler = proc_doulongvec_minmax,
+ },
+#endif
{
.procname = "swappiness",
.data = &vm_swappiness,
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index d4042e7..d738670 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -35,10 +35,8 @@
* As the vmscan reclaimer logic works with chunks which are multiple of
* SWAP_CLUSTER_MAX, it makes sense to use it for the window size as well.
*
- * TODO: Make the window size depend on machine size, as we do for vmstat
- * thresholds. Currently we set it to 512 pages (2MB for 4KB pages).
*/
-static const unsigned long vmpressure_win = SWAP_CLUSTER_MAX * 16;
+unsigned long vmpressure_win = SWAP_CLUSTER_MAX * 16;
/*
* These thresholds are used when we account memory pressure through
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 302dd07..ede68fd 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -20,6 +20,7 @@
#include <linux/writeback.h>
#include <linux/compaction.h>
#include <linux/mm_inline.h>
+#include <linux/swap.h>
#include "internal.h"
@@ -163,11 +164,13 @@ void refresh_zone_stat_thresholds(void)
struct zone *zone;
int cpu;
int threshold;
+ unsigned long new_vmpressure_win = 0;
for_each_populated_zone(zone) {
unsigned long max_drift, tolerate_drift;
threshold = calculate_normal_threshold(zone);
+ new_vmpressure_win += threshold;
for_each_online_cpu(cpu)
per_cpu_ptr(zone->pageset, cpu)->stat_threshold
@@ -184,6 +187,9 @@ void refresh_zone_stat_thresholds(void)
zone->percpu_drift_mark = high_wmark_pages(zone) +
max_drift;
}
+#ifdef CONFIG_MEMCG
+ vmpressure_win = new_vmpressure_win * SWAP_CLUSTER_MAX;
+#endif
}
void set_pgdat_percpu_threshold(pg_data_t *pgdat,
--
1.8.4.5
--
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