When a node reaches its low watermarks and wakes up kswapd, notify all
userspace programs waiting on the workingset page age histogram of the
memory pressure, so a userspace agent can read the workingset report in
time and make policy decisions, such as logging, oom-killing, or
migration.
Sysfs interface:
/sys/devices/system/node/nodeX/workingset_report/report_threshold
time in milliseconds that specifies how often the userspace
agent can be notified for node memory pressure.
Signed-off-by: Yuanchu Xie <yuanchu@xxxxxxxxxx>
---
include/linux/workingset_report.h | 4 +++
mm/internal.h | 6 +++++
mm/vmscan.c | 44 +++++++++++++++++++++++++++++++
mm/workingset_report.c | 39 +++++++++++++++++++++++++++
4 files changed, 93 insertions(+)
diff --git a/include/linux/workingset_report.h b/include/linux/workingset_report.h
index 23d2ae747a31..589d240d6251 100644
--- a/include/linux/workingset_report.h
+++ b/include/linux/workingset_report.h
@@ -35,7 +35,11 @@ struct wsr_page_age_histo {
};
struct wsr_state {
+ unsigned long report_threshold;
unsigned long refresh_interval;
+
+ struct kernfs_node *page_age_sys_file;
+
/* 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 151f09c6983e..36480c7ac0dd 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -209,8 +209,14 @@ extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason
/*
* in mm/wsr.c
*/
+void notify_workingset(struct mem_cgroup *memcg, struct pglist_data *pgdat);
/* Requires wsr->page_age_lock held */
void wsr_refresh_scan(struct lruvec *lruvec, unsigned long refresh_interval);
+#else
+static inline void notify_workingset(struct mem_cgroup *memcg,
+ struct pglist_data *pgdat)
+{
+}
#endif
/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5f04a04f5261..c6acd5265b3f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2535,6 +2535,15 @@ static bool can_age_anon_pages(struct pglist_data *pgdat,
return can_demote(pgdat->node_id, sc);
}
+#ifdef CONFIG_WORKINGSET_REPORT
+static void try_to_report_workingset(struct pglist_data *pgdat, struct scan_control *sc);
+#else
+static inline void try_to_report_workingset(struct pglist_data *pgdat,
+ struct scan_control *sc)
+{
+}
+#endif
+
#ifdef CONFIG_LRU_GEN
#ifdef CONFIG_LRU_GEN_ENABLED
@@ -3936,6 +3945,8 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
if (!min_ttl || sc->order || sc->priority == DEF_PRIORITY)
return;
+ try_to_report_workingset(pgdat, sc);
+
memcg = mem_cgroup_iter(NULL, NULL, NULL);
do {
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
@@ -5650,6 +5661,36 @@ void wsr_refresh_scan(struct lruvec *lruvec, unsigned long refresh_interval)
}
}
}
+
+static void try_to_report_workingset(struct pglist_data *pgdat,
+ struct scan_control *sc)
+{
+ struct mem_cgroup *memcg = sc->target_mem_cgroup;
+ struct wsr_state *wsr = &mem_cgroup_lruvec(memcg, pgdat)->wsr;
+ unsigned long threshold = READ_ONCE(wsr->report_threshold);
+
+ if (sc->priority == DEF_PRIORITY)
+ return;
+
+ if (!threshold)
+ return;
+
+ if (!mutex_trylock(&wsr->page_age_lock))
+ return;
+
+ if (!wsr->page_age) {
+ mutex_unlock(&wsr->page_age_lock);
+ return;
+ }
+
+ if (time_is_after_jiffies(wsr->page_age->timestamp + threshold)) {
+ mutex_unlock(&wsr->page_age_lock);
+ return;
+ }
+
+ mutex_unlock(&wsr->page_age_lock);
+ notify_workingset(memcg, pgdat);
+}
#endif /* CONFIG_WORKINGSET_REPORT */
#else /* !CONFIG_LRU_GEN */
@@ -6177,6 +6218,9 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
if (zone->zone_pgdat == last_pgdat)
continue;
last_pgdat = zone->zone_pgdat;
+
+ if (!sc->proactive)
+ try_to_report_workingset(zone->zone_pgdat, sc);
shrink_node(zone->zone_pgdat, sc);
}
diff --git a/mm/workingset_report.c b/mm/workingset_report.c
index 370e7d355604..3ed3b0e8f8ad 100644
--- a/mm/workingset_report.c
+++ b/mm/workingset_report.c
@@ -269,6 +269,33 @@ static struct wsr_state *kobj_to_wsr(struct kobject *kobj)
return &mem_cgroup_lruvec(NULL, kobj_to_pgdat(kobj))->wsr;
}
+static ssize_t report_threshold_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct wsr_state *wsr = kobj_to_wsr(kobj);
+ unsigned int threshold = READ_ONCE(wsr->report_threshold);
+
+ return sysfs_emit(buf, "%u\n", jiffies_to_msecs(threshold));
+}
+
+static ssize_t report_threshold_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t len)
+{
+ unsigned int threshold;
+ struct wsr_state *wsr = kobj_to_wsr(kobj);
+
+ if (kstrtouint(buf, 0, &threshold))
+ return -EINVAL;
+
+ WRITE_ONCE(wsr->report_threshold, msecs_to_jiffies(threshold));
+
+ return len;
+}
+
+static struct kobj_attribute report_threshold_attr =
+ __ATTR_RW(report_threshold);
+
static ssize_t refresh_interval_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -412,6 +439,7 @@ 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[] = {
+ &report_threshold_attr.attr,
&refresh_interval_attr.attr,
&page_age_intervals_attr.attr,
&page_age_attr.attr,
@@ -437,6 +465,9 @@ void wsr_register_node(struct node *node)
pr_warn("WSR failed to created group");
return;
}
+
+ wsr->page_age_sys_file =
+ kernfs_walk_and_get(kobj->sd, "workingset_report/page_age");
}
EXPORT_SYMBOL_GPL(wsr_register_node);
@@ -450,6 +481,14 @@ void wsr_unregister_node(struct node *node)
wsr = kobj_to_wsr(kobj);
sysfs_remove_group(kobj, &workingset_report_attr_group);
+ kernfs_put(wsr->page_age_sys_file);
wsr_destroy(mem_cgroup_lruvec(NULL, kobj_to_pgdat(kobj)));
}
EXPORT_SYMBOL_GPL(wsr_unregister_node);
+
+void notify_workingset(struct mem_cgroup *memcg, struct pglist_data *pgdat)
+{
+ struct wsr_state *wsr = &mem_cgroup_lruvec(memcg, pgdat)->wsr;
+
+ kernfs_notify(wsr->page_age_sys_file);
+}
--
2.44.0.396.g6e790dbe36-goog
