The refresh interval is a rate limiting factor to workingset page age
histogram reads. When a workingset report is generated, a timestamp
is noted, and the same report will be read until it expires beyond
the refresh interval, at which point a new report is generated.
Sysfs interface
/sys/devices/system/node/nodeX/workingset_report/refresh_interval
time in milliseconds specifying how long the report is valid for
Signed-off-by: Yuanchu Xie <yuanchu@xxxxxxxxxx>
---
include/linux/workingset_report.h | 1 +
mm/internal.h | 2 +-
mm/vmscan.c | 27 ++++++++------
mm/workingset_report.c | 58 ++++++++++++++++++++++++++-----
4 files changed, 69 insertions(+), 19 deletions(-)
diff --git a/include/linux/workingset_report.h b/include/linux/workingset_report.h
index 0de640cb1ef0..23d2ae747a31 100644
--- a/include/linux/workingset_report.h
+++ b/include/linux/workingset_report.h
@@ -35,6 +35,7 @@ struct wsr_page_age_histo {
};
struct wsr_state {
+ unsigned long refresh_interval;
/* breakdown of workingset by page age */
struct mutex page_age_lock;
struct wsr_page_age_histo *page_age;
diff --git a/mm/internal.h b/mm/internal.h
index 5e0caba64ee4..151f09c6983e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -210,7 +210,7 @@ extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason
* in mm/wsr.c
*/
/* Requires wsr->page_age_lock held */
-void wsr_refresh_scan(struct lruvec *lruvec);
+void wsr_refresh_scan(struct lruvec *lruvec, unsigned long refresh_interval);
#endif
/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b694d80ab2d1..5f04a04f5261 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -5620,7 +5620,7 @@ late_initcall(init_lru_gen);
* workingset reporting
******************************************************************************/
#ifdef CONFIG_WORKINGSET_REPORT
-void wsr_refresh_scan(struct lruvec *lruvec)
+void wsr_refresh_scan(struct lruvec *lruvec, unsigned long refresh_interval)
{
DEFINE_MAX_SEQ(lruvec);
struct scan_control sc = {
@@ -5633,15 +5633,22 @@ void wsr_refresh_scan(struct lruvec *lruvec)
};
unsigned int flags;
- set_task_reclaim_state(current, &sc.reclaim_state);
- flags = memalloc_noreclaim_save();
- /*
- * setting can_swap=true and force_scan=true ensures
- * proper workingset stats when the system cannot swap.
- */
- try_to_inc_max_seq(lruvec, max_seq, &sc, true, true);
- memalloc_noreclaim_restore(flags);
- set_task_reclaim_state(current, NULL);
+ if (refresh_interval) {
+ int gen = lru_gen_from_seq(max_seq);
+ unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
+
+ if (time_is_before_jiffies(birth + refresh_interval)) {
+ set_task_reclaim_state(current, &sc.reclaim_state);
+ flags = memalloc_noreclaim_save();
+ /*
+ * setting can_swap=true and force_scan=true ensures
+ * proper workingset stats when the system cannot swap.
+ */
+ try_to_inc_max_seq(lruvec, max_seq, &sc, true, true);
+ memalloc_noreclaim_restore(flags);
+ set_task_reclaim_state(current, NULL);
+ }
+ }
}
#endif /* CONFIG_WORKINGSET_REPORT */
diff --git a/mm/workingset_report.c b/mm/workingset_report.c
index 98cdaffcb6b4..370e7d355604 100644
--- a/mm/workingset_report.c
+++ b/mm/workingset_report.c
@@ -181,7 +181,8 @@ static void collect_page_age(struct wsr_page_age_histo *page_age,
/* First step: hierarchically scan child memcgs. */
static void refresh_scan(struct wsr_state *wsr, struct mem_cgroup *root,
- struct pglist_data *pgdat)
+ struct pglist_data *pgdat,
+ unsigned long refresh_interval)
{
struct mem_cgroup *memcg;
@@ -189,7 +190,7 @@ static void refresh_scan(struct wsr_state *wsr, struct mem_cgroup *root,
do {
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
- wsr_refresh_scan(lruvec);
+ wsr_refresh_scan(lruvec, refresh_interval);
cond_resched();
} while ((memcg = mem_cgroup_iter(root, memcg, NULL)));
}
@@ -231,16 +232,25 @@ static void refresh_aggregate(struct wsr_page_age_histo *page_age,
bool wsr_refresh_report(struct wsr_state *wsr, struct mem_cgroup *root,
struct pglist_data *pgdat)
{
- struct wsr_page_age_histo *page_age;
+ struct wsr_page_age_histo *page_age = NULL;
+ unsigned long refresh_interval = READ_ONCE(wsr->refresh_interval);
if (!READ_ONCE(wsr->page_age))
return false;
- refresh_scan(wsr, root, pgdat);
+ if (!refresh_interval)
+ return false;
+
mutex_lock(&wsr->page_age_lock);
page_age = READ_ONCE(wsr->page_age);
- if (page_age)
- refresh_aggregate(page_age, root, pgdat);
+ if (!page_age)
+ goto unlock;
+ if (time_is_after_jiffies(page_age->timestamp + refresh_interval))
+ goto unlock;
+ refresh_scan(wsr, root, pgdat, refresh_interval);
+ refresh_aggregate(page_age, root, pgdat);
+
+unlock:
mutex_unlock(&wsr->page_age_lock);
return !!page_age;
}
@@ -259,6 +269,35 @@ static struct wsr_state *kobj_to_wsr(struct kobject *kobj)
return &mem_cgroup_lruvec(NULL, kobj_to_pgdat(kobj))->wsr;
}
+static ssize_t refresh_interval_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct wsr_state *wsr = kobj_to_wsr(kobj);
+ unsigned int interval = READ_ONCE(wsr->refresh_interval);
+
+ return sysfs_emit(buf, "%u\n", jiffies_to_msecs(interval));
+}
+
+static ssize_t refresh_interval_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t len)
+{
+ unsigned int interval;
+ int err;
+ struct wsr_state *wsr = kobj_to_wsr(kobj);
+
+ err = kstrtouint(buf, 0, &interval);
+ if (err)
+ return err;
+
+ WRITE_ONCE(wsr->refresh_interval, msecs_to_jiffies(interval));
+
+ return len;
+}
+
+static struct kobj_attribute refresh_interval_attr =
+ __ATTR_RW(refresh_interval);
+
static ssize_t page_age_intervals_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -267,7 +306,7 @@ static ssize_t page_age_intervals_show(struct kobject *kobj,
mutex_lock(&wsr->page_age_lock);
- if (!!wsr->page_age) {
+ if (wsr->page_age) {
int i;
int nr_bins = wsr->page_age->bins.nr_bins;
@@ -373,7 +412,10 @@ static ssize_t page_age_show(struct kobject *kobj, struct kobj_attribute *attr,
static struct kobj_attribute page_age_attr = __ATTR_RO(page_age);
static struct attribute *workingset_report_attrs[] = {
- &page_age_intervals_attr.attr, &page_age_attr.attr, NULL
+ &refresh_interval_attr.attr,
+ &page_age_intervals_attr.attr,
+ &page_age_attr.attr,
+ NULL
};
static const struct attribute_group workingset_report_attr_group = {
--
2.44.0.396.g6e790dbe36-goog
